March full moon is the Worm Moon

Some on Earth will see a penumbral eclipse of the moon on the ight of March 24-25, 2024. Everyone on Earth will see the moon near the bright star Spica on this night. Here’s the view 2 hours after sunset on March 24, as seen from North America. At that time, the full Worm Moon glows brightly in the east above Spica, the brightest star in Virgo. Read about the penumbral lunar eclipse.

The March full moon 2024 is the closest full moon to the March equinox. It’s the full moon that sets 2024’s date of Easter Sunday as March 31. All the full moons have popular nicknames. Popular names for the March full moon are Worm Moon, Crow Moon and Sap Moon. The name Worm Moon honors the stirring of earthworms and insect larvae in the slowly warming late winter and early spring soil.

When to watch in 2024: Night of March 24-25

Where to look: Look for the bright round March full moon in the east in the evening, overhead around midnight, and in the west before sunrise. It is visible all night.
Crest of the full moon falls at 7 UTC on March 25, 2024. That’s 2 a.m. CDT in central North America. So if you live in central North America, your fullest moon will come before dawn on March 25, 2024.
There’s a penumbral lunar eclipse on March 24-24: Look for a penumbral eclipse beginning at 11:53 p.m. CDT on March 24 (4:53 UTC on March 25). It reaches mid-eclipse at 2:12 a.m. CDT on March 25 (7:12 UTC). The event ends at 4:33 a.m. CDT (9:33 UTC). At mid-eclipse the moon will be noticeably less bright. There will be a subtle shading on the moon: Earth’s lighter outer penumbral shadow.

At full moon, the sun, Earth and moon are aligned in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us.

Please help EarthSky keep going! Our annual crowd-funder is going on now. PLEASE DONATE today to continue enjoying updates on your cosmos and world.

March full moon sees a partial penumbral eclipse

Night owls will see the March full moon slide into a partial penumbral eclipse on March 25 beginning at 4:53 UTC. That is 11:53 p.m. CDT on March 24. It reaches mid-eclipse at 2:12 a.m. CDT and the event ends at 4:33 a.m. CDT. At mid-eclipse the moon’s brightness will have dimmed, but it will still be easily visible. From the moon’s point of view, Earth does not completely block the sun during a penumbral eclipse as would happen during a total umbral lunar eclipse.

From March 24 at 11:53 p.m. CDT until March 25 4:33 a.m., the full moon passes through Earth’s penumbral shadow. A small section of the lunar surface lies just outside the shadow, making this a partial penumbral lunar eclipse.

March full moons and Easter

The March full moon sometimes sets the date of Easter Sunday, as it does in 2024. In 2024, we have a full moon on March 24-25. Easter comes on the first Sunday following the full moon after the March equinox. So Easter is on March 31, 2024.

Read: When is Easter? And how is Easter tied to the night sky?

Opposite a Harvest Moon

The March 24 full moon is the closest full moon to 2024’s March equinox, which fell at 3:06 UTC on March 20.

It’s the spring equinox for the Northern Hemisphere. And it’s the autumn equinox for the Southern Hemisphere. So for us in the Northern Hemisphere, the March full moon shows characteristics opposite those of a Harvest Moon. Meanwhile, in the Southern Hemisphere, this full moon has all the Harvest Moon characteristics.

What are the Harvest Moon’s characteristics?

We in the Northern Hemisphere have a tradition of full moon names. We use the term Harvest Moon for the full moon nearest the autumn equinox, in September or October.

And many of the full moons do have unique, seasonal characteristics. All full moons rise at or around sunset. But – because the moon moves eastward in orbit – the moon typically rises about 50 minutes later with each passing day. And, around the time of the Harvest Moon, there’s only a short lag time between successive moonrises. The lag time between successive moonrises reaches a yearly minimum. For instance, at and around 40 degrees south latitude – around the time of the March full moon – the moon rises only about 30 to 35 minutes later daily.

So for the Southern Hemisphere, the short time between successive moonrises continues for several days. And – around the time of the autumn equinox and March full moon – there’s a bright full-looking moon in the early evening sky for several evenings in a row.

March full moon characteristics

In the Northern Hemisphere, in many years, the March full moon is the closest full moon to our spring equinox. So the lag time between successive moonrises reaches a yearly maximum. In other words, there’s an especially long time between moonrises, from one night to the next, around the time of the March full moon.

For instance, at 40 degrees north latitude, the moon rises some 75 minutes later from one night to the next around the time of the March full moon. The longer-than-usual time between successive moonrises continues for several days. So – around the time of the spring equinox and the March full moon – there’s a longer-than-usual period of darkness (no moon) in early evening, for several days in a row around new moon after the date of the full moon.

Arc of March full moon

And it’s not just moonrise times. It’s also the height of the moon’s arc across our sky that follows a specific pattern from month to month and season to season. Every full moon rises in the east as the sun sets in the west. Every full moon arcs across the sky throughout the night and sets around dawn. For us in the Northern Hemisphere, the arc of this March full moon is lower than the paths of the full moons of December, January and February. But it is higher than the paths in April, May, and June.

The arc across the sky of the March full moon lies midway between those of the December and June full moons. Its arc also matches that of the March sun.

For those in the Southern Hemisphere, the full moon’s arc across the sky is climbing higher with each successive month. It’ll continue to do so until around the June solstice.

March full moon in Virgo

The full moon on the night of March 24, 2024, is located in the direction of the constellation Virgo. It glows far above Virgo’s brightest star, Spica.

The March 2024 full moon occurs on the overnight of March 24 and lies in the constellation Virgo.

Penumbral lunar eclipse photos from our EarthSky community

Submit your photo to EarthSky here.

View at EarthSky Community Photos. | Here is the penumbral eclipse of July 4-5, 2020. As you can see, it’s not very noticeable. Greg Redfern in central Virginia commented: “Taken at maximum eclipse for the penumbral lunar eclipse. May be some shading in the upper left quadrant.” Thank you, Greg.

View at EarthSky Community Photos. | Soumyadeep Mukherjee of Kolkata, India, captured these images of the penumbral lunar eclipse on May 5, 2023, and wrote: “Last night, on 5th May 2023, we witnessed a penumbral lunar eclipse from Kolkata, India. Last night’s eclipse was pretty much observable with unaided eyes during its maximum. The eclipse continued for more than 4 hours. The image is a sequence of images captured during the eclipse. All the images are captured with the same exposure settings.” Thank you, Soumyadeep!

View at EarthSky Community Photos. | Niccole Neely captured this photo on the morning of November 30, 2020. She wrote: “I woke up at 2:30 this morning to catch the Beaver Moon penumbral lunar eclipse in Phoenix, Arizona.” Thank you, Niccole!

View at EarthSky Community Photos. | Nils Ribi in Sun Valley, Idaho, caught the November 30, 2020, penumbral lunar eclipse. He wrote: “The penumbral eclipse of the full moon, November 30, 2020, at 2:43 a.m., the time of greatest eclipse, in Sun Valley, Idaho. It was nice to see that the eclipse was not that faint here.” Thank you, Nils!

More photos of penumbral lunar eclipses

A full moon during a penumbral lunar eclipse with a slightly shadowed southeast curve. Image via NASA.

A penumbral lunar eclipse on November 20, 2002 in Dunkirk, Maryland. Image via Fred Espenak.

Bottom line: The March full moon on the overnight of March 24-25, 2024, is above the bright star Spica in the constellation Virgo. Watch for it from dusk to dawn and see the partial penumbral lunar eclipse beginning at 11:53 p.m. CDT on March 24!

The post March full moon is the Worm Moon first appeared on EarthSky.

from EarthSky https://ift.tt/aijDhTE

Some on Earth will see a penumbral eclipse of the moon on the ight of March 24-25, 2024. Everyone on Earth will see the moon near the bright star Spica on this night. Here’s the view 2 hours after sunset on March 24, as seen from North America. At that time, the full Worm Moon glows brightly in the east above Spica, the brightest star in Virgo. Read about the penumbral lunar eclipse.

The March full moon 2024 is the closest full moon to the March equinox. It’s the full moon that sets 2024’s date of Easter Sunday as March 31. All the full moons have popular nicknames. Popular names for the March full moon are Worm Moon, Crow Moon and Sap Moon. The name Worm Moon honors the stirring of earthworms and insect larvae in the slowly warming late winter and early spring soil.

When to watch in 2024: Night of March 24-25

Where to look: Look for the bright round March full moon in the east in the evening, overhead around midnight, and in the west before sunrise. It is visible all night.
Crest of the full moon falls at 7 UTC on March 25, 2024. That’s 2 a.m. CDT in central North America. So if you live in central North America, your fullest moon will come before dawn on March 25, 2024.
There’s a penumbral lunar eclipse on March 24-24: Look for a penumbral eclipse beginning at 11:53 p.m. CDT on March 24 (4:53 UTC on March 25). It reaches mid-eclipse at 2:12 a.m. CDT on March 25 (7:12 UTC). The event ends at 4:33 a.m. CDT (9:33 UTC). At mid-eclipse the moon will be noticeably less bright. There will be a subtle shading on the moon: Earth’s lighter outer penumbral shadow.

At full moon, the sun, Earth and moon are aligned in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us.

Please help EarthSky keep going! Our annual crowd-funder is going on now. PLEASE DONATE today to continue enjoying updates on your cosmos and world.

March full moon sees a partial penumbral eclipse

Night owls will see the March full moon slide into a partial penumbral eclipse on March 25 beginning at 4:53 UTC. That is 11:53 p.m. CDT on March 24. It reaches mid-eclipse at 2:12 a.m. CDT and the event ends at 4:33 a.m. CDT. At mid-eclipse the moon’s brightness will have dimmed, but it will still be easily visible. From the moon’s point of view, Earth does not completely block the sun during a penumbral eclipse as would happen during a total umbral lunar eclipse.

From March 24 at 11:53 p.m. CDT until March 25 4:33 a.m., the full moon passes through Earth’s penumbral shadow. A small section of the lunar surface lies just outside the shadow, making this a partial penumbral lunar eclipse.

March full moons and Easter

The March full moon sometimes sets the date of Easter Sunday, as it does in 2024. In 2024, we have a full moon on March 24-25. Easter comes on the first Sunday following the full moon after the March equinox. So Easter is on March 31, 2024.

Read: When is Easter? And how is Easter tied to the night sky?

Opposite a Harvest Moon

The March 24 full moon is the closest full moon to 2024’s March equinox, which fell at 3:06 UTC on March 20.

It’s the spring equinox for the Northern Hemisphere. And it’s the autumn equinox for the Southern Hemisphere. So for us in the Northern Hemisphere, the March full moon shows characteristics opposite those of a Harvest Moon. Meanwhile, in the Southern Hemisphere, this full moon has all the Harvest Moon characteristics.

What are the Harvest Moon’s characteristics?

We in the Northern Hemisphere have a tradition of full moon names. We use the term Harvest Moon for the full moon nearest the autumn equinox, in September or October.

And many of the full moons do have unique, seasonal characteristics. All full moons rise at or around sunset. But – because the moon moves eastward in orbit – the moon typically rises about 50 minutes later with each passing day. And, around the time of the Harvest Moon, there’s only a short lag time between successive moonrises. The lag time between successive moonrises reaches a yearly minimum. For instance, at and around 40 degrees south latitude – around the time of the March full moon – the moon rises only about 30 to 35 minutes later daily.

So for the Southern Hemisphere, the short time between successive moonrises continues for several days. And – around the time of the autumn equinox and March full moon – there’s a bright full-looking moon in the early evening sky for several evenings in a row.

March full moon characteristics

In the Northern Hemisphere, in many years, the March full moon is the closest full moon to our spring equinox. So the lag time between successive moonrises reaches a yearly maximum. In other words, there’s an especially long time between moonrises, from one night to the next, around the time of the March full moon.

For instance, at 40 degrees north latitude, the moon rises some 75 minutes later from one night to the next around the time of the March full moon. The longer-than-usual time between successive moonrises continues for several days. So – around the time of the spring equinox and the March full moon – there’s a longer-than-usual period of darkness (no moon) in early evening, for several days in a row around new moon after the date of the full moon.

Arc of March full moon

And it’s not just moonrise times. It’s also the height of the moon’s arc across our sky that follows a specific pattern from month to month and season to season. Every full moon rises in the east as the sun sets in the west. Every full moon arcs across the sky throughout the night and sets around dawn. For us in the Northern Hemisphere, the arc of this March full moon is lower than the paths of the full moons of December, January and February. But it is higher than the paths in April, May, and June.

The arc across the sky of the March full moon lies midway between those of the December and June full moons. Its arc also matches that of the March sun.

For those in the Southern Hemisphere, the full moon’s arc across the sky is climbing higher with each successive month. It’ll continue to do so until around the June solstice.

March full moon in Virgo

The full moon on the night of March 24, 2024, is located in the direction of the constellation Virgo. It glows far above Virgo’s brightest star, Spica.

The March 2024 full moon occurs on the overnight of March 24 and lies in the constellation Virgo.

Penumbral lunar eclipse photos from our EarthSky community

Submit your photo to EarthSky here.

View at EarthSky Community Photos. | Here is the penumbral eclipse of July 4-5, 2020. As you can see, it’s not very noticeable. Greg Redfern in central Virginia commented: “Taken at maximum eclipse for the penumbral lunar eclipse. May be some shading in the upper left quadrant.” Thank you, Greg.

View at EarthSky Community Photos. | Soumyadeep Mukherjee of Kolkata, India, captured these images of the penumbral lunar eclipse on May 5, 2023, and wrote: “Last night, on 5th May 2023, we witnessed a penumbral lunar eclipse from Kolkata, India. Last night’s eclipse was pretty much observable with unaided eyes during its maximum. The eclipse continued for more than 4 hours. The image is a sequence of images captured during the eclipse. All the images are captured with the same exposure settings.” Thank you, Soumyadeep!

View at EarthSky Community Photos. | Niccole Neely captured this photo on the morning of November 30, 2020. She wrote: “I woke up at 2:30 this morning to catch the Beaver Moon penumbral lunar eclipse in Phoenix, Arizona.” Thank you, Niccole!

View at EarthSky Community Photos. | Nils Ribi in Sun Valley, Idaho, caught the November 30, 2020, penumbral lunar eclipse. He wrote: “The penumbral eclipse of the full moon, November 30, 2020, at 2:43 a.m., the time of greatest eclipse, in Sun Valley, Idaho. It was nice to see that the eclipse was not that faint here.” Thank you, Nils!

More photos of penumbral lunar eclipses

A full moon during a penumbral lunar eclipse with a slightly shadowed southeast curve. Image via NASA.

A penumbral lunar eclipse on November 20, 2002 in Dunkirk, Maryland. Image via Fred Espenak.

Bottom line: The March full moon on the overnight of March 24-25, 2024, is above the bright star Spica in the constellation Virgo. Watch for it from dusk to dawn and see the partial penumbral lunar eclipse beginning at 11:53 p.m. CDT on March 24!

The post March full moon is the Worm Moon first appeared on EarthSky.

from EarthSky https://ift.tt/aijDhTE

1st eclipse season of 2024 starts March 24-25

View at EarthSky Community Photos. | Alan Howell from Albuquerque, New Mexico, took this photo in Mariposa Basin Park during the maximum annularity on October 14, 2023, and wrote: “What an incredible adventure! It took months of planning, gear testing, software and equipment training, booking flights and hotels, car traveling, weather forecast monitoring and location scouting to produce this colorized H-alpha image of the ‘ring of fire’ eclipse, showing prominences … This was certainly one of the most challenging and rewarding astrophotography images I’ve taken.” No doubt why … Very well done! We’re in the 1st eclipse season of 2024.

The first eclipse season for 2024 starts March 24. There will be a penumbral lunar eclipse on March 24-25, 2024, followed two weeks later by a total solar eclipse on April 8, 2024. These are two different kinds of eclipses: lunar and solar. But these two eclipses fall within a single eclipse season.

An eclipse season is an approximate 35-day period during which it’s inevitable for at least two (and possibly three) eclipses to take place.

Then, later this year, the September-October 2024 eclipse season will feature a very shallow partial lunar eclipse on September 17-18, 2024, and an annular solar eclipse on October 2, 2024.

What are eclipse seasons?

What’s an eclipse season? It’s an approximate 35-day period during which it’s inevitable that at least two (and possibly three) eclipses will take place. Typically, there are two eclipses in one eclipse season, and two eclipse seasons in one calendar year. So we typically have at least four eclipses per year. Eclipse seasons repeat in cycles of 173.3 days (somewhat shy of six calendar months).

So, why don’t you see that many eclipses then? To see a lunar eclipse, the moon has to be above your horizon. So it has to be night, or close to night, and that only happens for half of Earth at once. Solar eclipses are even harder to catch. In fact, a total solar eclipse can be seen only from a narrow track along Earth’s surface. The accompanying partial solar eclipse can be seen only in areas adjacent to that track.

Give back to astronomy with a donation to EarthSky.org! Your gift will support educational resources that teach people of all ages about space exploration and the fascinating facts about our universe.

2024 has 2 eclipse seasons

The March-April 2024 eclipse season features a penumbral lunar eclipse on March 24-25, 2024. And a total solar eclipse on April 8, 2024.

The September-October eclipse season features a very shallow partial lunar eclipse on September 17-18, 2024, and an annular solar eclipse on October 2, 2024.

By the way, in 2024, the middle of the eclipse seasons falls on April 5 and September 29. At the middle of an eclipse season, which recurs in periods of about 173 days, the lunar nodes are in exact alignment with the Earth and sun.

What causes an eclipse season?

There are many cycles in the heavens. In fact, an eclipse season is just one of these many celestial cycles.

Consider a scenario where the moon orbited Earth on the same plane as the Earth orbits the sun. Then we’d have a solar eclipse at every new moon, and a lunar eclipse at every full moon.

But, in reality, the moon’s orbit is inclined by five degrees to the ecliptic (Earth’s orbital plane). Most of the time the new moon or full moon swings too far north, or south, of the ecliptic for an eclipse to take place.

For instance, in the year 2024, we will have 13 new moons and 12 full moons, but only two solar eclipses and two lunar eclipses.

In the year 2024, there are 13 new moons and 12 full moons. Moon phases table via Fred Espenak/ AstroPixels.com. Used with permission.

Why we have eclipses

Eclipses are all about alignments. In a solar eclipse, the sun, moon and Earth line up, with the moon in the middle. Image via NASA.

In a lunar eclipse, the sun, Earth and moon line up, with the Earth in the middle. Image via NASA.

Earth (shown as a white dot in the center of each blue disk) at each date when it’s aligned with the sun and moon. The moon is shown on the outer edge of the blue disk, it’s either sunward from it (new moon) or outward from it (full moon). The blue disk is the plane of the moon’s orbit around Earth, darker blue for the half north of the ecliptic. This plane gradually rotates backward. There is an eclipse if the moon is new or full when near ascending or descending node through the ecliptic plane. Small arrows show the moon’s course over 7 days. Image via Guy Ottewell. Used with permission.

Nodal precession of the lunar nodes as the Earth revolves around the sun causes an eclipse season approximately every six months. Image via Nela/ Wikimedia Commons. CC BY-SA 4.0.

Lunar nodes point at the sun

Twice every month, as the moon circles Earth in its orbit, the moon crosses the ecliptic (Earth’s orbital plane) at points called nodes. If the moon is going from south to north, it’s called the moon’s ascending node. If the moon is moving from north to south, it’s called the moon’s descending node.

Read more: Node passages of the moon: 2001 to 2100

Whenever the lunar nodes point directly at the sun, that momentous event marks the middle of the eclipse season. The alignment of the moon, sun and Earth is most exact when an eclipse happens at the middle of an eclipse season. And the least so when an eclipse occurs at the start, or the end, of an eclipse season. Any lunar eclipse happening early or late in the eclipse season presents a penumbral lunar eclipse, whereas any solar eclipse happening early or late in the eclipse season features a skimpy partial eclipse of the sun.

The plane of the moon’s orbit is inclined at 5 degrees to the plane of Earth’s orbit around the sun (the ecliptic). The moon’s orbit intersects the ecliptic at two points called nodes (labeled here as N1 and N2). It’s the middle of the eclipse season whenever this line of nodes points directly at the sun. In the above diagram, the line of nodes does not point at the sun. Image via Wikimedia Commons (public domain).

2 or 3 eclipses in one eclipse season?

An eclipse season most often presents only two eclipses. However, if the first eclipse falls early in the eclipse season, then it’s possible for a third eclipse to occur before the eclipse season ends.

For example, the last time three eclipses happened in one eclipse season was June-July 2020:

June 5, 2020: Penumbral lunar eclipse
June 21, 2020: Annular solar eclipse
July 5, 2020: Penumbral lunar eclipse

Likewise, the next time three eclipses will occur in one eclipse season will be June-July 2029:

June 12, 2029: Partial solar eclipse
June 26, 2029: Total lunar eclipse
July 11, 2029: Partial solar eclipse

Read more: How often are there three eclipses in a month?

Eclipse season terminology

With this in mind, here are some words you need to know to understand eclipse seasons: lunar nodes and ecliptic. The ecliptic is the plane of the Earth’s orbit around the sun. A lunar node is the point where, in its monthly orbit of Earth, the moon’s orbit intersects that plane. An eclipse season is when – from Earth’s perspective – the sun is close enough to a lunar node to allow an eclipse to take place. If the sun is close to a lunar node at full moon, we see a lunar eclipse. If the sun is close to a lunar node at new moon, we see a solar eclipse.

To put it another way, if the moon turns new or full in close concert with the moon’s crossing of one of its nodes, then an eclipse is not only possible, but inevitable.

The moon’s orbit around Earth is inclined 5 degrees to Earth’s orbit around the sun, so the moon crosses the Earth’s orbital plane twice a month at points called nodes. Every 173.3 days, the line of nodes points at the sun, and this is the middle of the approximate 5-week eclipse season (highlighted in gray). During any eclipse season, there is always at least one solar eclipse and one lunar eclipse, occurring within one fortnight of the other. If the 1st eclipse arrives early enough in the eclipse season, 3 eclipses can fit within a lunar month, and up to 7 eclipses occur in one year’s time. Image via Wikimedia Commons (public domain).

Minimum of 4 eclipses in one year

A lunar month (period of time between successive new moons or successive full moons) is about 29.5 days long. So a minimum of two eclipses (one solar and one lunar, in either order) happens in one eclipse season. A maximum of three eclipses is possible (either lunar/solar/lunar or solar/lunar/solar), though the first eclipse of the eclipse season has to come quite early to allow for a third eclipse near the end.

So a minimum of two lunar eclipses and two solar eclipses occur in one calendar year. Yet, depending on how the eclipse seasons and lunar phases align, it’s possible to also have five, six or seven eclipses in one year.

For the maximum of seven eclipses to occur in one calendar year, the first eclipse must come in early January. That leaves enough room for the seventh eclipse in late December. In one scenario, an eclipse season sporting two eclipses comes early in the year and late in the year. The middle eclipse season stages three eclipses.

It’s quite rare for seven eclipses to occur in one calendar year, however. Seven eclipses last happened in the year 1982, and will next occur in the year 2038.

Maximum of 7 eclipses in one year

Also, it’s remotely possible for a calendar year to sport two eclipse seasons with three eclipses each, and one eclipse from an eclipse season that straddles into the previous or following year. By way of example, we present the years 1935 and 1879-80.

View at EarthSky Community Photos. | Eliot Herman at 39,000 feet (12,000 meters) over Ontario captured this photo of the ring of fire on June 10, 2021. He wrote: “I was on the Sky and Telescope annular eclipse flight over Ontario, Canada. Viewing prospects for the eclipse on the ground were not promising given weather and virus closures. We had a great view from the air with the sun in eclipse well above the clouds. The flight was great fun for the eclipse chasers.” Thanks, Eliot!

View at EarthSky Community Photos. | Shaun Tarpley in League City, Texas, captured an incredibly vibrant shot of the lunar eclipse of May 15, 2022, and wrote: “This image was taken from my backyard. The iOptron Skyguider Pro allowed me to take this 13 second image at roughly 700mm to bring out the detail in the moon and sky.” Thank you, Shaun!

Bottom line: Eclipse seasons are periods during which eclipses not only can take place, but must take place. A minimum of two eclipses (one solar and one lunar, in either order) happens in one eclipse season. A maximum of three eclipses is possible (either lunar/solar/lunar, or solar/lunar/solar). In 2024, the eclipse seasons are in March-April, and then again in September-October.

Read more: Total solar eclipse on April 8, 2024

The post 1st eclipse season of 2024 starts March 24-25 first appeared on EarthSky.

from EarthSky https://ift.tt/skuvo67

View at EarthSky Community Photos. | Alan Howell from Albuquerque, New Mexico, took this photo in Mariposa Basin Park during the maximum annularity on October 14, 2023, and wrote: “What an incredible adventure! It took months of planning, gear testing, software and equipment training, booking flights and hotels, car traveling, weather forecast monitoring and location scouting to produce this colorized H-alpha image of the ‘ring of fire’ eclipse, showing prominences … This was certainly one of the most challenging and rewarding astrophotography images I’ve taken.” No doubt why … Very well done! We’re in the 1st eclipse season of 2024.

The first eclipse season for 2024 starts March 24. There will be a penumbral lunar eclipse on March 24-25, 2024, followed two weeks later by a total solar eclipse on April 8, 2024. These are two different kinds of eclipses: lunar and solar. But these two eclipses fall within a single eclipse season.

An eclipse season is an approximate 35-day period during which it’s inevitable for at least two (and possibly three) eclipses to take place.

Then, later this year, the September-October 2024 eclipse season will feature a very shallow partial lunar eclipse on September 17-18, 2024, and an annular solar eclipse on October 2, 2024.

What are eclipse seasons?

What’s an eclipse season? It’s an approximate 35-day period during which it’s inevitable that at least two (and possibly three) eclipses will take place. Typically, there are two eclipses in one eclipse season, and two eclipse seasons in one calendar year. So we typically have at least four eclipses per year. Eclipse seasons repeat in cycles of 173.3 days (somewhat shy of six calendar months).

So, why don’t you see that many eclipses then? To see a lunar eclipse, the moon has to be above your horizon. So it has to be night, or close to night, and that only happens for half of Earth at once. Solar eclipses are even harder to catch. In fact, a total solar eclipse can be seen only from a narrow track along Earth’s surface. The accompanying partial solar eclipse can be seen only in areas adjacent to that track.

Give back to astronomy with a donation to EarthSky.org! Your gift will support educational resources that teach people of all ages about space exploration and the fascinating facts about our universe.

2024 has 2 eclipse seasons

The March-April 2024 eclipse season features a penumbral lunar eclipse on March 24-25, 2024. And a total solar eclipse on April 8, 2024.

The September-October eclipse season features a very shallow partial lunar eclipse on September 17-18, 2024, and an annular solar eclipse on October 2, 2024.

By the way, in 2024, the middle of the eclipse seasons falls on April 5 and September 29. At the middle of an eclipse season, which recurs in periods of about 173 days, the lunar nodes are in exact alignment with the Earth and sun.

What causes an eclipse season?

There are many cycles in the heavens. In fact, an eclipse season is just one of these many celestial cycles.

Consider a scenario where the moon orbited Earth on the same plane as the Earth orbits the sun. Then we’d have a solar eclipse at every new moon, and a lunar eclipse at every full moon.

But, in reality, the moon’s orbit is inclined by five degrees to the ecliptic (Earth’s orbital plane). Most of the time the new moon or full moon swings too far north, or south, of the ecliptic for an eclipse to take place.

For instance, in the year 2024, we will have 13 new moons and 12 full moons, but only two solar eclipses and two lunar eclipses.

In the year 2024, there are 13 new moons and 12 full moons. Moon phases table via Fred Espenak/ AstroPixels.com. Used with permission.

Why we have eclipses

Eclipses are all about alignments. In a solar eclipse, the sun, moon and Earth line up, with the moon in the middle. Image via NASA.

In a lunar eclipse, the sun, Earth and moon line up, with the Earth in the middle. Image via NASA.

Earth (shown as a white dot in the center of each blue disk) at each date when it’s aligned with the sun and moon. The moon is shown on the outer edge of the blue disk, it’s either sunward from it (new moon) or outward from it (full moon). The blue disk is the plane of the moon’s orbit around Earth, darker blue for the half north of the ecliptic. This plane gradually rotates backward. There is an eclipse if the moon is new or full when near ascending or descending node through the ecliptic plane. Small arrows show the moon’s course over 7 days. Image via Guy Ottewell. Used with permission.

Nodal precession of the lunar nodes as the Earth revolves around the sun causes an eclipse season approximately every six months. Image via Nela/ Wikimedia Commons. CC BY-SA 4.0.

Lunar nodes point at the sun

Twice every month, as the moon circles Earth in its orbit, the moon crosses the ecliptic (Earth’s orbital plane) at points called nodes. If the moon is going from south to north, it’s called the moon’s ascending node. If the moon is moving from north to south, it’s called the moon’s descending node.

Read more: Node passages of the moon: 2001 to 2100

Whenever the lunar nodes point directly at the sun, that momentous event marks the middle of the eclipse season. The alignment of the moon, sun and Earth is most exact when an eclipse happens at the middle of an eclipse season. And the least so when an eclipse occurs at the start, or the end, of an eclipse season. Any lunar eclipse happening early or late in the eclipse season presents a penumbral lunar eclipse, whereas any solar eclipse happening early or late in the eclipse season features a skimpy partial eclipse of the sun.

The plane of the moon’s orbit is inclined at 5 degrees to the plane of Earth’s orbit around the sun (the ecliptic). The moon’s orbit intersects the ecliptic at two points called nodes (labeled here as N1 and N2). It’s the middle of the eclipse season whenever this line of nodes points directly at the sun. In the above diagram, the line of nodes does not point at the sun. Image via Wikimedia Commons (public domain).

2 or 3 eclipses in one eclipse season?

An eclipse season most often presents only two eclipses. However, if the first eclipse falls early in the eclipse season, then it’s possible for a third eclipse to occur before the eclipse season ends.

For example, the last time three eclipses happened in one eclipse season was June-July 2020:

June 5, 2020: Penumbral lunar eclipse
June 21, 2020: Annular solar eclipse
July 5, 2020: Penumbral lunar eclipse

Likewise, the next time three eclipses will occur in one eclipse season will be June-July 2029:

June 12, 2029: Partial solar eclipse
June 26, 2029: Total lunar eclipse
July 11, 2029: Partial solar eclipse

Read more: How often are there three eclipses in a month?

Eclipse season terminology

With this in mind, here are some words you need to know to understand eclipse seasons: lunar nodes and ecliptic. The ecliptic is the plane of the Earth’s orbit around the sun. A lunar node is the point where, in its monthly orbit of Earth, the moon’s orbit intersects that plane. An eclipse season is when – from Earth’s perspective – the sun is close enough to a lunar node to allow an eclipse to take place. If the sun is close to a lunar node at full moon, we see a lunar eclipse. If the sun is close to a lunar node at new moon, we see a solar eclipse.

To put it another way, if the moon turns new or full in close concert with the moon’s crossing of one of its nodes, then an eclipse is not only possible, but inevitable.

The moon’s orbit around Earth is inclined 5 degrees to Earth’s orbit around the sun, so the moon crosses the Earth’s orbital plane twice a month at points called nodes. Every 173.3 days, the line of nodes points at the sun, and this is the middle of the approximate 5-week eclipse season (highlighted in gray). During any eclipse season, there is always at least one solar eclipse and one lunar eclipse, occurring within one fortnight of the other. If the 1st eclipse arrives early enough in the eclipse season, 3 eclipses can fit within a lunar month, and up to 7 eclipses occur in one year’s time. Image via Wikimedia Commons (public domain).

Minimum of 4 eclipses in one year

A lunar month (period of time between successive new moons or successive full moons) is about 29.5 days long. So a minimum of two eclipses (one solar and one lunar, in either order) happens in one eclipse season. A maximum of three eclipses is possible (either lunar/solar/lunar or solar/lunar/solar), though the first eclipse of the eclipse season has to come quite early to allow for a third eclipse near the end.

So a minimum of two lunar eclipses and two solar eclipses occur in one calendar year. Yet, depending on how the eclipse seasons and lunar phases align, it’s possible to also have five, six or seven eclipses in one year.

For the maximum of seven eclipses to occur in one calendar year, the first eclipse must come in early January. That leaves enough room for the seventh eclipse in late December. In one scenario, an eclipse season sporting two eclipses comes early in the year and late in the year. The middle eclipse season stages three eclipses.

It’s quite rare for seven eclipses to occur in one calendar year, however. Seven eclipses last happened in the year 1982, and will next occur in the year 2038.

Maximum of 7 eclipses in one year

Also, it’s remotely possible for a calendar year to sport two eclipse seasons with three eclipses each, and one eclipse from an eclipse season that straddles into the previous or following year. By way of example, we present the years 1935 and 1879-80.

View at EarthSky Community Photos. | Eliot Herman at 39,000 feet (12,000 meters) over Ontario captured this photo of the ring of fire on June 10, 2021. He wrote: “I was on the Sky and Telescope annular eclipse flight over Ontario, Canada. Viewing prospects for the eclipse on the ground were not promising given weather and virus closures. We had a great view from the air with the sun in eclipse well above the clouds. The flight was great fun for the eclipse chasers.” Thanks, Eliot!

View at EarthSky Community Photos. | Shaun Tarpley in League City, Texas, captured an incredibly vibrant shot of the lunar eclipse of May 15, 2022, and wrote: “This image was taken from my backyard. The iOptron Skyguider Pro allowed me to take this 13 second image at roughly 700mm to bring out the detail in the moon and sky.” Thank you, Shaun!

Bottom line: Eclipse seasons are periods during which eclipses not only can take place, but must take place. A minimum of two eclipses (one solar and one lunar, in either order) happens in one eclipse season. A maximum of three eclipses is possible (either lunar/solar/lunar, or solar/lunar/solar). In 2024, the eclipse seasons are in March-April, and then again in September-October.

Read more: Total solar eclipse on April 8, 2024

The post 1st eclipse season of 2024 starts March 24-25 first appeared on EarthSky.

from EarthSky https://ift.tt/skuvo67

Use the Big Dipper to find Polaris, the North Star

An imaginary line drawn from the 2 outermost stars in the bowl of the Big Dipper always points to Polaris.

People are always asking how to find Polaris, the North Star. It’s easy! If you can find the Big Dipper in the northern sky, you can find Polaris.

Use the Big Dipper to find Polaris

A well-known trick for finding Polaris – the legendary North Star – is that the two outermost stars in the bowl of the Big Dipper point to it. Hence, they’re well known among amateur astronomers by the nickname The Pointers. They call those stars Dubhe and Merak.

At one time, sailors’ livelihoods and survival depended on these pointer stars of the Big Dipper. In fact, many considered them their lucky stars. Scouts also learn to use the Big Dipper and Polaris to find the direction north.

Polaris isn’t the brightest star in the sky, as is commonly believed. Instead, it’s a moderately bright 2nd-magnitude star. But it’s bright enough to be easily seen in a dark sky. Unlike the other stars – which either rise in the east and set in the west, or else wheel in a circle around Polaris – the North Star appears fixed in the northern sky.

The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. The Dipper is circumpolar at 41 degrees north latitude, and all latitudes farther north. Image via Mjchael/ Wikipedia (CC BY-SA 2.5).

March is excellent for the Dipper

By the way, for evening skywatchers in the Northern Hemisphere, spring is the best time of year to see the Big Dipper. Also, just remember during the evening hours, it’s best viewed in the spring, and worst in autumn. Every March, at nightfall and early evening, the seven stars of the Big Dipper climb into your sky, ascending above the northeastern horizon.

From the northern part of the Northern Hemisphere, the Big and Little Dippers are in the sky continuously. In fact, they are always above your horizon, circling endlessly around Polaris. So, given an unobstructed horizon, latitudes north of the 35th parallel (the approximate location of the Mediterranean Sea and Tennessee’s southern border) can expect to see the Big Dipper at any hour of the night every day of the year.

Likewise, for the the Southern Hemisphere, the Big Dipper is visible from about 26 degrees south latitude and all latitudes farther north.

The Big Dipper is an asterism

Also, the Big Dipper itself isn’t a constellation. It’s an asterism, a recognizable pattern of stars on the sky’s dome.

It is part of the constellation Ursa Major the Great Bear. Indeed, it really does look like a dipper, and it’s pretty bright. Some sources say the Dipper makes up the Bear’s (rather unusual) tail and hindquarters.

You can see the Bear, too, if you watch for the Dipper in March under a very dark sky.

Use Polaris to find directions

If you stand facing Polaris, then, you’re facing the direction north. So, if you place Polaris to your back, you’re facing south. You can use Polaris to find directions only in the Northern Hemisphere, however. South of the equator, Polaris drops below the northern horizon.

Images from our community

View at EarthSky Community Photos. | Cecille Kennedy in Depoe Bay, Oregon, caught the Big Dipper and Little Dipper on June 9, 2021. She wrote: “The 2 stars that form the side of the Big Dipper, opposite the handle, point to Polaris, the North Star. Polaris is the last star in the handle of the Little Dipper.” Thank you, Cecille!

View larger. | South of the equator, Polaris can’t be seen. Otherwise, if you can see the Big Dipper, you can find Polaris. Tom Wildoner of the Dark Side Observatory shared this shot with us. He captured it around 3:30 a.m. in the month of July. Thanks, Tom! Used with permission.

Bottom line: Use the Big Dipper to find Polaris, the North Star.

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

Donate: Your support means the world to us

The post Use the Big Dipper to find Polaris, the North Star first appeared on EarthSky.

from EarthSky https://ift.tt/3aksnuE

An imaginary line drawn from the 2 outermost stars in the bowl of the Big Dipper always points to Polaris.

People are always asking how to find Polaris, the North Star. It’s easy! If you can find the Big Dipper in the northern sky, you can find Polaris.

Use the Big Dipper to find Polaris

A well-known trick for finding Polaris – the legendary North Star – is that the two outermost stars in the bowl of the Big Dipper point to it. Hence, they’re well known among amateur astronomers by the nickname The Pointers. They call those stars Dubhe and Merak.

At one time, sailors’ livelihoods and survival depended on these pointer stars of the Big Dipper. In fact, many considered them their lucky stars. Scouts also learn to use the Big Dipper and Polaris to find the direction north.

Polaris isn’t the brightest star in the sky, as is commonly believed. Instead, it’s a moderately bright 2nd-magnitude star. But it’s bright enough to be easily seen in a dark sky. Unlike the other stars – which either rise in the east and set in the west, or else wheel in a circle around Polaris – the North Star appears fixed in the northern sky.

The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. The Dipper is circumpolar at 41 degrees north latitude, and all latitudes farther north. Image via Mjchael/ Wikipedia (CC BY-SA 2.5).

March is excellent for the Dipper

By the way, for evening skywatchers in the Northern Hemisphere, spring is the best time of year to see the Big Dipper. Also, just remember during the evening hours, it’s best viewed in the spring, and worst in autumn. Every March, at nightfall and early evening, the seven stars of the Big Dipper climb into your sky, ascending above the northeastern horizon.

From the northern part of the Northern Hemisphere, the Big and Little Dippers are in the sky continuously. In fact, they are always above your horizon, circling endlessly around Polaris. So, given an unobstructed horizon, latitudes north of the 35th parallel (the approximate location of the Mediterranean Sea and Tennessee’s southern border) can expect to see the Big Dipper at any hour of the night every day of the year.

Likewise, for the the Southern Hemisphere, the Big Dipper is visible from about 26 degrees south latitude and all latitudes farther north.

The Big Dipper is an asterism

Also, the Big Dipper itself isn’t a constellation. It’s an asterism, a recognizable pattern of stars on the sky’s dome.

It is part of the constellation Ursa Major the Great Bear. Indeed, it really does look like a dipper, and it’s pretty bright. Some sources say the Dipper makes up the Bear’s (rather unusual) tail and hindquarters.

You can see the Bear, too, if you watch for the Dipper in March under a very dark sky.

Use Polaris to find directions

If you stand facing Polaris, then, you’re facing the direction north. So, if you place Polaris to your back, you’re facing south. You can use Polaris to find directions only in the Northern Hemisphere, however. South of the equator, Polaris drops below the northern horizon.

Images from our community

View at EarthSky Community Photos. | Cecille Kennedy in Depoe Bay, Oregon, caught the Big Dipper and Little Dipper on June 9, 2021. She wrote: “The 2 stars that form the side of the Big Dipper, opposite the handle, point to Polaris, the North Star. Polaris is the last star in the handle of the Little Dipper.” Thank you, Cecille!

View larger. | South of the equator, Polaris can’t be seen. Otherwise, if you can see the Big Dipper, you can find Polaris. Tom Wildoner of the Dark Side Observatory shared this shot with us. He captured it around 3:30 a.m. in the month of July. Thanks, Tom! Used with permission.

Bottom line: Use the Big Dipper to find Polaris, the North Star.

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

Donate: Your support means the world to us

The post Use the Big Dipper to find Polaris, the North Star first appeared on EarthSky.

from EarthSky https://ift.tt/3aksnuE

Possible hycean world found by Webb telescope

View larger. | This is an artist’s concept of a hycean world. These exoplanets are thought to have deep hydrogen atmospheres and global water oceans on their surfaces. Image via Pablo Carlos Budassi/ Wikimedia Commons (CC BY SA 4.0).

Meet TOI-270 d, a possible hycean world

• Recent research suggests that exoplanet TOI-270 d is likely a hycean planet – a world with a global ocean beneath a thick hydrogen atmosphere – located 70 light-years from Earth.
• But another research team thinks the planet is too hot to be considered hycean. Temperatures on its sunlit side might be as high as 7,200 degrees Fahrenheit (4,000 degrees Celsius).
• Both research groups also identified the presence of carbon disulfide, a compound potentially linked to biological activity on Earth, but also produced through alternative processes in hydrogen-rich atmospheres.

Hycean worlds are planets with global oceans beneath a thick hydrogen atmosphere. Scientists say they may be common in our galaxy. Researchers at the University of Cambridge in the U.K. said that the exoplanet TOI-270 d is likely a hycean planet. Their study is based on data from NASA’s James Webb Space Telescope. The Guardian newspaper first reported the tantalizing discovery on March 8, 2024. Another international research team, led by the University of Montreal in Canada, however, isn’t convinced yet that TOI-270 d really is an ocean world, saying it is likely too hot.

The U.K. researchers published their peer-reviewed paper in the journal Astronomy & Astrophysics on March 7, 2024. The Canadian and international research team submitted their paper to arXiv on March 5, 2024.

Is this sub-Neptune a hot ocean planet?

TOI-270 d is about twice the diameter of Earth and is 70 light-years away. Astronomers classify it as a sub-Neptune.

Nikku Madhusudhan at the University of Cambridge co-led the analysis of data about TOI-270 d. He explained that the ocean, if actually there, is likely quite hot:

The ocean could be upwards of 212 degrees Fahrenheit (100 degrees Celsius) or more. At high atmospheric pressure, an ocean this hot could still be liquid, but it’s not clear if it would be habitable.

The data from Webb shows that the atmosphere of the planet contains water vapor, methane and carbon dioxide. That is consistent with an atmosphere that is predominantly hydrogen, with a global water ocean beneath it. There is also a lack of ammonia, which also supports the hycean ocean world scenario. That’s because chemistry says it should occur naturally in a hydrogen atmosphere. But it would be depleted if there was an ocean because ammonia is highly soluble in water. Madhusudhan said:

One interpretation is that this is a so-called “hycean” world, with a water ocean under a hydrogen-rich atmosphere.

Please help EarthSky continue its mission to bring you night sky information and science news! Will you join our annual crowd-funding campaign with a donation today?

Too hot for an ocean?

The results are tantalizing, but not conclusive yet. With this in mind, another research team, led by Björn Benneke at the University of Montreal in Quebec, Canada, said that the planet would probably be hot for liquid water. They found the same gases in the atmosphere as the other team, but calculate the atmosphere could be much hotter, as much as 7,200 degrees Fahrenheit (4,000 degrees Celsius).

Benneke told The Guardian:

The temperature in our view is too warm for water to be liquid.

He and his team also think that there is too much water vapor in the atmosphere. They suggest that this wouldn’t leave enough water to form an ocean. Instead, the water might be in a supercritical state, called a supercritical fluid (SFC). A supercritical fluid is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. This makes it more difficult to distinguish between a liquid and gas. Benneke said that:

… It’s almost like a thick, hot fluid.

In this scenario, instead of being a hycean ocean world, the planet would have a rocky surface with no ocean. The atmosphere would be dense with hydrogen and water vapor.

An ocean world unlike Earth

If TOI-270 d does have an ocean, conditions wouldn’t be exactly like those on Earth. This is because the planet is tidally locked to its star. Much as one side of the moon always faces Earth, one side of TOI-270 d always faces its star. This means that one side is always in sunlight while the other is in perpetual night. As a result, temperatures on the sunlight side are always hotter. As Madhusudhan said in The Guardian:

The ocean would be extremely hot on the day side. The night side could potentially host habitable conditions.

Also, the hydrogen atmosphere would have crushing pressure, tens or hundreds of times that of Earth’s atmosphere. Reminiscent of Venus, but even more so. The ocean itself would also be different to those on Earth, perhaps up to hundreds of times deeper than Earth’s oceans. The seabed, instead of rock, would likely be high-pressure ice, also known as Ice VI. Even deeper down, a rocky core.

View larger. | Artist’s illustration of the James Webb Space Telescope. Webb discovered the potential new ocean exoplanet. Image via NASA.

Carbon disulfide

Along with the other atmospheric gases, both research teams also discovered something else: carbon disulfide. On Earth, it can be related to biological activity. But as the researchers point out, other processes can produce it as well, especially in hydrogen atmospheres. So it’s interesting, but not proof of life. As Madhusudhan explained:

We can’t tie [carbon disulfide] to biological activity. In a hydrogen-rich atmosphere, it is relatively easy to make it. But if we’re able to measure the unique molecule it’s promising that we should be able to measure habitable planets in the future.

We need to be extremely careful about how we communicate findings on this kind of object. It’s easy for the public to jump on to the idea that we’re finding life already.

The finding is similar to that of K2-18 b, another sub-Neptune with a deep hydrogen atmosphere. Last year, scientists announced a tentative detection of dimethyl sulfide (DMS) in its atmosphere.

On Earth, the molecule is only known to be produced by life, or in a laboratory. But the detection was weak, and scientists are still debating whether it actually exists on K2-18 b or not.

Bottom line: NASA’s Webb Space Telescope has discovered a possible hycean world, with a deep hydrogen atmosphere and a global water ocean. Or is this world too hot?

Source: Possible hycean conditions in the sub-Neptune TOI-270 d

Source: JWST Reveals CH4, CO2, and H2O in a Metal-rich Miscible Atmosphere on a Two-Earth-Radius Exoplanet

Via The Guardian

Read more: Hycean planets might be habitable ocean worlds

Read more: Is this nearby exoplanet a water world? Or a mini-Neptune?

The post Possible hycean world found by Webb telescope first appeared on EarthSky.

from EarthSky https://ift.tt/60ecRDn

View larger. | This is an artist’s concept of a hycean world. These exoplanets are thought to have deep hydrogen atmospheres and global water oceans on their surfaces. Image via Pablo Carlos Budassi/ Wikimedia Commons (CC BY SA 4.0).

Meet TOI-270 d, a possible hycean world

• Recent research suggests that exoplanet TOI-270 d is likely a hycean planet – a world with a global ocean beneath a thick hydrogen atmosphere – located 70 light-years from Earth.
• But another research team thinks the planet is too hot to be considered hycean. Temperatures on its sunlit side might be as high as 7,200 degrees Fahrenheit (4,000 degrees Celsius).
• Both research groups also identified the presence of carbon disulfide, a compound potentially linked to biological activity on Earth, but also produced through alternative processes in hydrogen-rich atmospheres.

Hycean worlds are planets with global oceans beneath a thick hydrogen atmosphere. Scientists say they may be common in our galaxy. Researchers at the University of Cambridge in the U.K. said that the exoplanet TOI-270 d is likely a hycean planet. Their study is based on data from NASA’s James Webb Space Telescope. The Guardian newspaper first reported the tantalizing discovery on March 8, 2024. Another international research team, led by the University of Montreal in Canada, however, isn’t convinced yet that TOI-270 d really is an ocean world, saying it is likely too hot.

The U.K. researchers published their peer-reviewed paper in the journal Astronomy & Astrophysics on March 7, 2024. The Canadian and international research team submitted their paper to arXiv on March 5, 2024.

Is this sub-Neptune a hot ocean planet?

TOI-270 d is about twice the diameter of Earth and is 70 light-years away. Astronomers classify it as a sub-Neptune.

Nikku Madhusudhan at the University of Cambridge co-led the analysis of data about TOI-270 d. He explained that the ocean, if actually there, is likely quite hot:

The ocean could be upwards of 212 degrees Fahrenheit (100 degrees Celsius) or more. At high atmospheric pressure, an ocean this hot could still be liquid, but it’s not clear if it would be habitable.

The data from Webb shows that the atmosphere of the planet contains water vapor, methane and carbon dioxide. That is consistent with an atmosphere that is predominantly hydrogen, with a global water ocean beneath it. There is also a lack of ammonia, which also supports the hycean ocean world scenario. That’s because chemistry says it should occur naturally in a hydrogen atmosphere. But it would be depleted if there was an ocean because ammonia is highly soluble in water. Madhusudhan said:

One interpretation is that this is a so-called “hycean” world, with a water ocean under a hydrogen-rich atmosphere.

Please help EarthSky continue its mission to bring you night sky information and science news! Will you join our annual crowd-funding campaign with a donation today?

Too hot for an ocean?

The results are tantalizing, but not conclusive yet. With this in mind, another research team, led by Björn Benneke at the University of Montreal in Quebec, Canada, said that the planet would probably be hot for liquid water. They found the same gases in the atmosphere as the other team, but calculate the atmosphere could be much hotter, as much as 7,200 degrees Fahrenheit (4,000 degrees Celsius).

Benneke told The Guardian:

The temperature in our view is too warm for water to be liquid.

He and his team also think that there is too much water vapor in the atmosphere. They suggest that this wouldn’t leave enough water to form an ocean. Instead, the water might be in a supercritical state, called a supercritical fluid (SFC). A supercritical fluid is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. This makes it more difficult to distinguish between a liquid and gas. Benneke said that:

… It’s almost like a thick, hot fluid.

In this scenario, instead of being a hycean ocean world, the planet would have a rocky surface with no ocean. The atmosphere would be dense with hydrogen and water vapor.

An ocean world unlike Earth

If TOI-270 d does have an ocean, conditions wouldn’t be exactly like those on Earth. This is because the planet is tidally locked to its star. Much as one side of the moon always faces Earth, one side of TOI-270 d always faces its star. This means that one side is always in sunlight while the other is in perpetual night. As a result, temperatures on the sunlight side are always hotter. As Madhusudhan said in The Guardian:

The ocean would be extremely hot on the day side. The night side could potentially host habitable conditions.

Also, the hydrogen atmosphere would have crushing pressure, tens or hundreds of times that of Earth’s atmosphere. Reminiscent of Venus, but even more so. The ocean itself would also be different to those on Earth, perhaps up to hundreds of times deeper than Earth’s oceans. The seabed, instead of rock, would likely be high-pressure ice, also known as Ice VI. Even deeper down, a rocky core.

View larger. | Artist’s illustration of the James Webb Space Telescope. Webb discovered the potential new ocean exoplanet. Image via NASA.

Carbon disulfide

Along with the other atmospheric gases, both research teams also discovered something else: carbon disulfide. On Earth, it can be related to biological activity. But as the researchers point out, other processes can produce it as well, especially in hydrogen atmospheres. So it’s interesting, but not proof of life. As Madhusudhan explained:

We can’t tie [carbon disulfide] to biological activity. In a hydrogen-rich atmosphere, it is relatively easy to make it. But if we’re able to measure the unique molecule it’s promising that we should be able to measure habitable planets in the future.

We need to be extremely careful about how we communicate findings on this kind of object. It’s easy for the public to jump on to the idea that we’re finding life already.

The finding is similar to that of K2-18 b, another sub-Neptune with a deep hydrogen atmosphere. Last year, scientists announced a tentative detection of dimethyl sulfide (DMS) in its atmosphere.

On Earth, the molecule is only known to be produced by life, or in a laboratory. But the detection was weak, and scientists are still debating whether it actually exists on K2-18 b or not.

Bottom line: NASA’s Webb Space Telescope has discovered a possible hycean world, with a deep hydrogen atmosphere and a global water ocean. Or is this world too hot?

Source: Possible hycean conditions in the sub-Neptune TOI-270 d

Source: JWST Reveals CH4, CO2, and H2O in a Metal-rich Miscible Atmosphere on a Two-Earth-Radius Exoplanet

Via The Guardian

Read more: Hycean planets might be habitable ocean worlds

Read more: Is this nearby exoplanet a water world? Or a mini-Neptune?

The post Possible hycean world found by Webb telescope first appeared on EarthSky.

from EarthSky https://ift.tt/60ecRDn

Jupiter’s stormy weather on display in new Hubble images

View larger. | NASA’s Hubble Space Telescope captured these views (opposite hemispheres) of Jupiter’s stormy weather. Image via NASA/ ESA/ STScI/ Amy Simon (NASA-GSFC).

• New images of Jupiter from the Hubble Space Telescope the whole of the gas giant as it rotates. These images provide insights into Jupiter’s stormy weather patterns.
• Jupiter’s weather is intense, due the fact that its atmosphere is tens of thousands of miles deep with no solid surface beneath. The thick jovian atmosphere hosts big and little storms, including cyclones and anticyclones, some larger than Earth.
• The new images show Jupiter’s famous Great Red Spot, plus what scientists call Red Spot Jr., a smaller anticyclone that brushes past the Great Red Spot about every two years.

Hubble watches Jupiter’s stormy weather

Jupiter – biggest planet in our solar system – is a dynamic world! Its deep atmosphere is constantly churning with cyclones, wind shear and other violent storms. The Great Red Spot is the largest and most well-known of Jupiter’s storms. And Jupiter is also famous for its distinct red-and-tan cloud bands, which you can see even in small telescopes. On March 14, 2024, NASA released new images of the gas giant planet, taken by the Hubble Space Telescope. Hubble has been busy tracking Jupiter’s stormy weather. The new images, taken on January 5-6, 2024, show both hemispheres of this mighty world, as it spins on its axis once about every 10 hours.

Hubble took the images as part of the Outer Planet Atmospheres Legacy program (OPAL). In OPAL, Hubble monitors all the giant planets – Jupiter, Saturn, Uranus and Neptune – and their weather systems every year. Scientists call it Hubble’s Grand Tour of the Outer Solar System. Unlike the smaller rocky planets (with the exception of Venus), these gas and ice giants are completely blanketed by deep, turbulent atmospheres. Ferocious winds churn up the clouds and hazes. Hence, weather patterns are always changing, and scientists want to keep track of the changes.

On Jupiter in particular, storms of various sizes – some much larger than Earth – churn in the atmosphere. These include both cyclones and anticyclones, rotating in opposite directions to each other. This shows that there are high-pressure and low-pressure weather systems that sometimes interact with each other.

Help spread the wonders of astronomy! Please donate now to EarthSky.org and ensure that people around the world can learn about the night sky and our universe.

The new images in detail

Indeed, there is much to see in the new images. In the left image above, you can easily see Jupiter’s Great Red Spot, even though it has been gradually shrinking in size. To its lower right is Red Spot Jr., a much smaller anticyclone. It formed when two other storms merged together in 1998 and 2000. Its color has varied over the years as well. It was distinctly red in 2006, then became paler. Now, in 2024, it looks redder again.

The Great Red Spot and Red Spot Jr. don’t collide, but they do pass each other about every two years.

Bouncing and repelling storms

And there’s more! The right image, above, shows the opposite hemisphere of Jupiter as it rotated into view. Another cyclone and anticyclone appear close together, both deeply red in color. The cyclone features an upwelling of clouds on the edges. Other clouds are descending in the middle of the cyclone. This causes a clearing in the otherwise obscuring atmospheric haze. Scientists say these storms should bounce past and repel each other, because they’re rotating in opposite directions. OPAL project lead Amy Simon at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said:

The many large storms and small white clouds are a hallmark of a lot of activity going on in Jupiter’s atmosphere right now.

View larger. | 12-panel sequence of images from Hubble showing Jupiter from January 5-6, 2024. Image via NASA/ ESA/ Joseph DePasquale (STScI).

This video shows a full rotation of Jupiter for OPAL 2024. Hubble snapshots of the planet, taken January 5-6, 2024, have been photo-mapped onto a sphere, and the model is then rotated in animation. Video via NASA/ ESA/ Amy Simon (NASA-GSFC)/ Joseph DePasquale (STScI).

In addition, you can see Jupiter’s volcanic moon Io to the left of the planet in the right image. In fact, Io is the most volcanically active known body in the solar system, even more than Earth.

Deep, turbulent atmosphere

Jupiter’s atmosphere is tens of thousands of miles deep, with no solid surface below. And, along with the other storms, there are also clouds of ammonia ice crystals. By comparison, they are only about 30 miles (48 km) thick. These clouds also give Jupiter its banded appearance. In the bands, air is flowing up to almost 350 miles per hour (560 km/h) in different directions and at various latitudes.

Last January, the ESPRESSO planet-hunter also turned its gaze to Jupiter, capturing some stunning views. ESPRESSO is the spectrograph on the Very Large Telescope (VLT) in Chile, designed primarily to look for exoplanets.

And, speaking of Jupiter, have you seen these photos of the moon and Jupiter together? EarthSky readers took these images on March 13 and 14, 2024.

Bottom line: NASA’s Hubble Space Telescope has sent back new images of Jupiter’s stormy weather. Hubble monitors the atmospheres of all the giant planets every year.

Via Hubblesite/NASA

Read more: The ESPRESSO planet-hunter looks at Jupiter

Read more: Jupiter’s moon Io as you’ve never seen it

The post Jupiter’s stormy weather on display in new Hubble images first appeared on EarthSky.

from EarthSky https://ift.tt/yqZLFh0

View larger. | NASA’s Hubble Space Telescope captured these views (opposite hemispheres) of Jupiter’s stormy weather. Image via NASA/ ESA/ STScI/ Amy Simon (NASA-GSFC).

• New images of Jupiter from the Hubble Space Telescope the whole of the gas giant as it rotates. These images provide insights into Jupiter’s stormy weather patterns.
• Jupiter’s weather is intense, due the fact that its atmosphere is tens of thousands of miles deep with no solid surface beneath. The thick jovian atmosphere hosts big and little storms, including cyclones and anticyclones, some larger than Earth.
• The new images show Jupiter’s famous Great Red Spot, plus what scientists call Red Spot Jr., a smaller anticyclone that brushes past the Great Red Spot about every two years.

Hubble watches Jupiter’s stormy weather

Jupiter – biggest planet in our solar system – is a dynamic world! Its deep atmosphere is constantly churning with cyclones, wind shear and other violent storms. The Great Red Spot is the largest and most well-known of Jupiter’s storms. And Jupiter is also famous for its distinct red-and-tan cloud bands, which you can see even in small telescopes. On March 14, 2024, NASA released new images of the gas giant planet, taken by the Hubble Space Telescope. Hubble has been busy tracking Jupiter’s stormy weather. The new images, taken on January 5-6, 2024, show both hemispheres of this mighty world, as it spins on its axis once about every 10 hours.

Hubble took the images as part of the Outer Planet Atmospheres Legacy program (OPAL). In OPAL, Hubble monitors all the giant planets – Jupiter, Saturn, Uranus and Neptune – and their weather systems every year. Scientists call it Hubble’s Grand Tour of the Outer Solar System. Unlike the smaller rocky planets (with the exception of Venus), these gas and ice giants are completely blanketed by deep, turbulent atmospheres. Ferocious winds churn up the clouds and hazes. Hence, weather patterns are always changing, and scientists want to keep track of the changes.

On Jupiter in particular, storms of various sizes – some much larger than Earth – churn in the atmosphere. These include both cyclones and anticyclones, rotating in opposite directions to each other. This shows that there are high-pressure and low-pressure weather systems that sometimes interact with each other.

Help spread the wonders of astronomy! Please donate now to EarthSky.org and ensure that people around the world can learn about the night sky and our universe.

The new images in detail

Indeed, there is much to see in the new images. In the left image above, you can easily see Jupiter’s Great Red Spot, even though it has been gradually shrinking in size. To its lower right is Red Spot Jr., a much smaller anticyclone. It formed when two other storms merged together in 1998 and 2000. Its color has varied over the years as well. It was distinctly red in 2006, then became paler. Now, in 2024, it looks redder again.

The Great Red Spot and Red Spot Jr. don’t collide, but they do pass each other about every two years.

Bouncing and repelling storms

And there’s more! The right image, above, shows the opposite hemisphere of Jupiter as it rotated into view. Another cyclone and anticyclone appear close together, both deeply red in color. The cyclone features an upwelling of clouds on the edges. Other clouds are descending in the middle of the cyclone. This causes a clearing in the otherwise obscuring atmospheric haze. Scientists say these storms should bounce past and repel each other, because they’re rotating in opposite directions. OPAL project lead Amy Simon at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said:

The many large storms and small white clouds are a hallmark of a lot of activity going on in Jupiter’s atmosphere right now.

View larger. | 12-panel sequence of images from Hubble showing Jupiter from January 5-6, 2024. Image via NASA/ ESA/ Joseph DePasquale (STScI).

This video shows a full rotation of Jupiter for OPAL 2024. Hubble snapshots of the planet, taken January 5-6, 2024, have been photo-mapped onto a sphere, and the model is then rotated in animation. Video via NASA/ ESA/ Amy Simon (NASA-GSFC)/ Joseph DePasquale (STScI).

In addition, you can see Jupiter’s volcanic moon Io to the left of the planet in the right image. In fact, Io is the most volcanically active known body in the solar system, even more than Earth.

Deep, turbulent atmosphere

Jupiter’s atmosphere is tens of thousands of miles deep, with no solid surface below. And, along with the other storms, there are also clouds of ammonia ice crystals. By comparison, they are only about 30 miles (48 km) thick. These clouds also give Jupiter its banded appearance. In the bands, air is flowing up to almost 350 miles per hour (560 km/h) in different directions and at various latitudes.

Last January, the ESPRESSO planet-hunter also turned its gaze to Jupiter, capturing some stunning views. ESPRESSO is the spectrograph on the Very Large Telescope (VLT) in Chile, designed primarily to look for exoplanets.

And, speaking of Jupiter, have you seen these photos of the moon and Jupiter together? EarthSky readers took these images on March 13 and 14, 2024.

Bottom line: NASA’s Hubble Space Telescope has sent back new images of Jupiter’s stormy weather. Hubble monitors the atmospheres of all the giant planets every year.

Via Hubblesite/NASA

Read more: The ESPRESSO planet-hunter looks at Jupiter

Read more: Jupiter’s moon Io as you’ve never seen it

The post Jupiter’s stormy weather on display in new Hubble images first appeared on EarthSky.

from EarthSky https://ift.tt/yqZLFh0

Equinox sun rises due east and sets due west

The equinox is on March 19-20, 2024. At the equinoxes, the ecliptic and the celestial equator intersect. See the intersection point on this imaginary great circle, representing the dome of Earth’s sky? The celestial equator is directly above Earth’s equator. The ecliptic is the sun’s apparent path across our sky. And the celestial equator intersects your horizon at points due east and due west. That’s why – at every equinox, no matter where you are on the globe – the sun, on the celestial equator, rises due east and sets due west. Read more about the equinox sun below. Image via NASA.

The March equinox happens at 3:06 UTC on March 20, 2024 (10:06 p.m. CDT on March 19.)

The equinox sun rises due east and sets due west

It’s not true that day and night are precisely equal on the day of an equinox. But here’s an equinox fact that is true. The sun rises due east and sets due west at the equinox. It might seem counterintuitive. But it’s true no matter where you live on Earth (except at the North and South Poles). Here’s how to visualize it.

To understand the nearly due-east and due-west rising and setting of an equinox sun, you have to think of the reality of Earth in space. First think about why the sun’s path across our sky shifts from season to season. That’s because our world is tilted on its axis with respect to its orbit around the sun.

Join us in making sure everyone has access to the wonders of astronomy. Donate now!

Our seasons result from the Earth’s rotational axis tilting 23.5 degrees out of the perpendicular to the ecliptic, or Earth’s orbital plane. Image via National Weather Service/ weather.gov.

Now think about what is an equinox. It’s an event that happens on the imaginary dome of Earth’s sky. And it marks that special moment when the sun crosses the celestial equator going from one hemisphere to the other. Of course, it also represents a point in Earth’s orbit.

The celestial equator

The celestial equator is a great circle dividing the imaginary celestial sphere into its northern and southern hemispheres. Additionally, the celestial equator wraps the sky directly above Earth’s equator. Following the September equinox, the sun crosses the celestial equator to enter the sky’s Southern Hemisphere.

All these components are imaginary, yet what happens at every equinox is very real. In fact, it’s as real as the sun’s passage across the sky each day and as real as the change of seasons.

It’s the same all over the globe

So no matter where you are on Earth (except for the North and South Poles), you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator, the imaginary great circle above the true equator of Earth.

And that’s why the sun rises close to due east and sets close to due west, for all of us, at the equinox. The equinox sun is on the celestial equator. Which means, no matter where you are on Earth, the celestial equator intersects your horizon at due east and due west.

This fact makes the day of an equinox a good day for finding east and west from your yard or favorite site for watching the sky. Just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.

If you do this, you’ll be able to use those landmarks to find those cardinal directions in the weeks and months ahead. Plus, you’ll know those directions long after Earth has moved on in its orbit around the sun.

The history of the seasons

Our ancestors may not have understood the equinoxes and solstices as events that occur during Earth’s yearly orbit around the sun. But if they were observant – and some were very observant indeed – they surely marked the day of the equinox as being midway between the sun’s lowest path across the sky in winter and highest path across the sky in summer.

Now we can say with reasonably high accuracy that the sun rises due east and sets due west on the day of the equinox. And this is the same for everyone around the globe.

If you are seeking more precision for the sunrise/sunset direction in your part of the world, check out the altitude/azimuth for the sun via timeanddate.com.

EarthSky’s Raúl Cortés caught the March equinox sun at sunrise in 2021. Thanks, Raúl! See more of Raúl’s photos here.

Bottom line: The 2024 March equinox occurs on March 20 at 3:06 UTC (10:06 p.m. CDT on March 19). At the equinox, the sun rises and sets due east and due west.

March equinox 2024: Everything you need to know

Hamal: Ancient equinox star

The post Equinox sun rises due east and sets due west first appeared on EarthSky.

from EarthSky https://ift.tt/pasOZdQ

The equinox is on March 19-20, 2024. At the equinoxes, the ecliptic and the celestial equator intersect. See the intersection point on this imaginary great circle, representing the dome of Earth’s sky? The celestial equator is directly above Earth’s equator. The ecliptic is the sun’s apparent path across our sky. And the celestial equator intersects your horizon at points due east and due west. That’s why – at every equinox, no matter where you are on the globe – the sun, on the celestial equator, rises due east and sets due west. Read more about the equinox sun below. Image via NASA.

The March equinox happens at 3:06 UTC on March 20, 2024 (10:06 p.m. CDT on March 19.)

The equinox sun rises due east and sets due west

It’s not true that day and night are precisely equal on the day of an equinox. But here’s an equinox fact that is true. The sun rises due east and sets due west at the equinox. It might seem counterintuitive. But it’s true no matter where you live on Earth (except at the North and South Poles). Here’s how to visualize it.

To understand the nearly due-east and due-west rising and setting of an equinox sun, you have to think of the reality of Earth in space. First think about why the sun’s path across our sky shifts from season to season. That’s because our world is tilted on its axis with respect to its orbit around the sun.

Join us in making sure everyone has access to the wonders of astronomy. Donate now!

Our seasons result from the Earth’s rotational axis tilting 23.5 degrees out of the perpendicular to the ecliptic, or Earth’s orbital plane. Image via National Weather Service/ weather.gov.

Now think about what is an equinox. It’s an event that happens on the imaginary dome of Earth’s sky. And it marks that special moment when the sun crosses the celestial equator going from one hemisphere to the other. Of course, it also represents a point in Earth’s orbit.

The celestial equator

The celestial equator is a great circle dividing the imaginary celestial sphere into its northern and southern hemispheres. Additionally, the celestial equator wraps the sky directly above Earth’s equator. Following the September equinox, the sun crosses the celestial equator to enter the sky’s Southern Hemisphere.

All these components are imaginary, yet what happens at every equinox is very real. In fact, it’s as real as the sun’s passage across the sky each day and as real as the change of seasons.

It’s the same all over the globe

So no matter where you are on Earth (except for the North and South Poles), you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator, the imaginary great circle above the true equator of Earth.

And that’s why the sun rises close to due east and sets close to due west, for all of us, at the equinox. The equinox sun is on the celestial equator. Which means, no matter where you are on Earth, the celestial equator intersects your horizon at due east and due west.

This fact makes the day of an equinox a good day for finding east and west from your yard or favorite site for watching the sky. Just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.

If you do this, you’ll be able to use those landmarks to find those cardinal directions in the weeks and months ahead. Plus, you’ll know those directions long after Earth has moved on in its orbit around the sun.

The history of the seasons

Our ancestors may not have understood the equinoxes and solstices as events that occur during Earth’s yearly orbit around the sun. But if they were observant – and some were very observant indeed – they surely marked the day of the equinox as being midway between the sun’s lowest path across the sky in winter and highest path across the sky in summer.

Now we can say with reasonably high accuracy that the sun rises due east and sets due west on the day of the equinox. And this is the same for everyone around the globe.

If you are seeking more precision for the sunrise/sunset direction in your part of the world, check out the altitude/azimuth for the sun via timeanddate.com.

EarthSky’s Raúl Cortés caught the March equinox sun at sunrise in 2021. Thanks, Raúl! See more of Raúl’s photos here.

Bottom line: The 2024 March equinox occurs on March 20 at 3:06 UTC (10:06 p.m. CDT on March 19). At the equinox, the sun rises and sets due east and due west.

March equinox 2024: Everything you need to know

Hamal: Ancient equinox star

The post Equinox sun rises due east and sets due west first appeared on EarthSky.

from EarthSky https://ift.tt/pasOZdQ

March equinox 2024: All you need to know

Happy March equinox, y’all!

What is it? The March equinox – aka the vernal equinox – marks the sun’s crossing above Earth’s equator, moving from south to north. Earth’s tilt on its axis is what causes this northward shift of the sun’s path across our sky at this time of year. Earth’s tilt is now bringing spring and summer to the Northern Hemisphere. At the same time, the March equinox marks the beginning of autumn – and a shift toward winter – in the Southern Hemisphere.
When is it? The sun will cross the celestial equator – a line directly above Earth’s equator – at 3:06 UTC on March 20, 2024 (10:06 p.m. CDT on March 19).

No matter where you are on Earth, the equinox brings us a number of seasonal effects, noticeable to nature lovers around the globe.

Join us in making sure everyone has access to the wonders of astronomy. Donate now!

Equal day and night on the equinox?

At the equinox, Earth’s two hemispheres are receiving the sun’s rays equally. Night and day are often said to be equal in length. In fact, the word equinox comes from the Latin aequus (equal) and nox (night). For our ancestors, whose timekeeping was less precise than ours, day and night likely did seem equal. But today we know it’s not exactly so.

Read more: Are day and night equal at the equinox?

Fastest sunsets at the equinoxes

The fastest sunsets and sunrises of the year happen at the equinoxes. We’re talking here about the length of time it takes for the whole sun to sink below the horizon.

Read more: Fastest sunsets happen near equinoxes

View at EarthSky Community Photos. | Iaroslav Kourzenkov of Halifax, Nova Scotia, Canada, captured this image of the sunset on the equinox on March 20, 2023. Thank you, Iaroslav!

Sun rises due east and sets due west?

Here’s another equinox phenomenon. You might hear that the sun rises due east and sets due west at the equinox. Is that true? Yes it is. In fact, it’s the case no matter where you live on Earth, with the exception of the North and South Poles. At the equinoxes, the sun appears overhead at noon as seen from Earth’s equator, as the illustration below shows. This illustration shows the sun’s location on the celestial equator, every hour, on the day of the equinox.

No matter where you are on Earth – except at the Earth’s North and South Poles – you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator: the imaginary line above the true equator of the Earth.

The sun is on the celestial equator, and the celestial equator intersects all of our horizons at points due east and due west. Voila! The sun rises due east and sets due west.

Read more: Sun rises due east and sets due west

The day arc of the sun, every hour, at the equinox, as seen on the (imaginary) celestial sphere surrounding Earth. At the equinox, the sun is directly above Earth’s equator. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

More March equinox effects

And there are also plenty more effects in play around the time of the March equinox that all of us can notice. In the Northern Hemisphere, the March equinox brings earlier sunrises, later sunsets and sprouting plants.

Meanwhile, you’ll find the opposite season – later sunrises, earlier sunsets, chillier winds, dry and falling leaves – south of the equator.

The equinoxes and solstices are caused by Earth’s tilt on its axis and ceaseless motion in orbit. You can think of an equinox as happening on the imaginary dome of our sky, or as an event that happens in Earth’s orbit around the sun.

The Earth-centered view

If you think of it from an Earth-centered perspective, you can think of the celestial equator as a great circle dividing Earth’s sky into its Northern and Southern Hemispheres. The celestial equator is an imaginary line wrapping the sky directly above Earth’s equator. At the equinox, the sun crosses the celestial equator to enter the sky’s Northern Hemisphere.

This illustration shows the day arc of the equinox sun, as seen from Earth’s equator. Also showing are twilight suns (in red) down to -18 degrees altitude. Note that the sun is at its highest point at noon. And see that the tree’s shadow at noon is cast straight down. That is – as seen from the equator on the day of an equinox – a tree stands in the center of its own shadow. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

The Earth-in-space view

If you think of it from an Earth-in-space perspective, you have to think of Earth in orbit around the sun. And we all know Earth doesn’t orbit upright but is instead tilted on its axis by 23 1/2 degrees. So Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. We have an equinox twice a year – spring and fall – when the tilt of the Earth’s axis and Earth’s orbit around the sun combine in such a way that the axis is inclined neither away from nor toward the sun.

Here are satellite views of Earth on the solstices and equinoxes, via NASA Earth Observatory.

Things change fast around the equinoxes

Since Earth never stops moving around the sun, the position of the sunrise and sunset – and the days of approximately equal sunlight and night – will change quickly.

The video below was the Astronomy Picture of the Day for March 19, 2014. APOD explained:

At an equinox, the Earth’s terminator – the dividing line between day and night – becomes vertical and connects the North and South Poles. The time-lapse video [below] demonstrates this by displaying an entire year on planet Earth in 12 seconds. From geosynchronous orbit, the Meteosat satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical.

As the Earth revolved around the sun, the terminator was seen to tilt in a way that provides less daily sunlight to the Northern Hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the Southern Hemisphere and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken – and will take – around the sun.

The equinox is an event that takes place in Earth’s orbit around the sun. Image via National Weather Service/ weather.gov.

Where are signs of the March equinox in nature?

Everywhere! Forget about the weather for a moment, and think only about daylight. In terms of daylight, the knowledge that spring is here – and summer is coming – permeates all of nature on the northern half of Earth’s globe.

Notice the arc of the sun across the sky each day. You’ll find that it’s shifting toward the north. Responding to the change in daylight, birds and butterflies are migrating back northward, too, along with the path of the sun.

The longer days do bring with them warmer weather. People are leaving their winter coats at home. Trees are budding, and plants are beginning a new cycle of growth. In many places, spring flowers are beginning to bloom.

Meanwhile, in the Southern Hemisphere, the days are getting shorter and nights longer. A chill is in the air. Fall is here, and winter is coming!

Bottom line: The 2024 March equinox falls March 20 at 3:06 UTC. So many parts of the world will see the equinox arrive on March 19. What is an equinox? How do we experience it on Earth? All you need to know, here.

The post March equinox 2024: All you need to know first appeared on EarthSky.

from EarthSky https://ift.tt/r7FmfMe

Happy March equinox, y’all!

What is it? The March equinox – aka the vernal equinox – marks the sun’s crossing above Earth’s equator, moving from south to north. Earth’s tilt on its axis is what causes this northward shift of the sun’s path across our sky at this time of year. Earth’s tilt is now bringing spring and summer to the Northern Hemisphere. At the same time, the March equinox marks the beginning of autumn – and a shift toward winter – in the Southern Hemisphere.
When is it? The sun will cross the celestial equator – a line directly above Earth’s equator – at 3:06 UTC on March 20, 2024 (10:06 p.m. CDT on March 19).

No matter where you are on Earth, the equinox brings us a number of seasonal effects, noticeable to nature lovers around the globe.

Join us in making sure everyone has access to the wonders of astronomy. Donate now!

Equal day and night on the equinox?

At the equinox, Earth’s two hemispheres are receiving the sun’s rays equally. Night and day are often said to be equal in length. In fact, the word equinox comes from the Latin aequus (equal) and nox (night). For our ancestors, whose timekeeping was less precise than ours, day and night likely did seem equal. But today we know it’s not exactly so.

Read more: Are day and night equal at the equinox?

Fastest sunsets at the equinoxes

The fastest sunsets and sunrises of the year happen at the equinoxes. We’re talking here about the length of time it takes for the whole sun to sink below the horizon.

Read more: Fastest sunsets happen near equinoxes

View at EarthSky Community Photos. | Iaroslav Kourzenkov of Halifax, Nova Scotia, Canada, captured this image of the sunset on the equinox on March 20, 2023. Thank you, Iaroslav!

Sun rises due east and sets due west?

Here’s another equinox phenomenon. You might hear that the sun rises due east and sets due west at the equinox. Is that true? Yes it is. In fact, it’s the case no matter where you live on Earth, with the exception of the North and South Poles. At the equinoxes, the sun appears overhead at noon as seen from Earth’s equator, as the illustration below shows. This illustration shows the sun’s location on the celestial equator, every hour, on the day of the equinox.

No matter where you are on Earth – except at the Earth’s North and South Poles – you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator: the imaginary line above the true equator of the Earth.

The sun is on the celestial equator, and the celestial equator intersects all of our horizons at points due east and due west. Voila! The sun rises due east and sets due west.

Read more: Sun rises due east and sets due west

The day arc of the sun, every hour, at the equinox, as seen on the (imaginary) celestial sphere surrounding Earth. At the equinox, the sun is directly above Earth’s equator. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

More March equinox effects

And there are also plenty more effects in play around the time of the March equinox that all of us can notice. In the Northern Hemisphere, the March equinox brings earlier sunrises, later sunsets and sprouting plants.

Meanwhile, you’ll find the opposite season – later sunrises, earlier sunsets, chillier winds, dry and falling leaves – south of the equator.

The equinoxes and solstices are caused by Earth’s tilt on its axis and ceaseless motion in orbit. You can think of an equinox as happening on the imaginary dome of our sky, or as an event that happens in Earth’s orbit around the sun.

The Earth-centered view

If you think of it from an Earth-centered perspective, you can think of the celestial equator as a great circle dividing Earth’s sky into its Northern and Southern Hemispheres. The celestial equator is an imaginary line wrapping the sky directly above Earth’s equator. At the equinox, the sun crosses the celestial equator to enter the sky’s Northern Hemisphere.

This illustration shows the day arc of the equinox sun, as seen from Earth’s equator. Also showing are twilight suns (in red) down to -18 degrees altitude. Note that the sun is at its highest point at noon. And see that the tree’s shadow at noon is cast straight down. That is – as seen from the equator on the day of an equinox – a tree stands in the center of its own shadow. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

The Earth-in-space view

If you think of it from an Earth-in-space perspective, you have to think of Earth in orbit around the sun. And we all know Earth doesn’t orbit upright but is instead tilted on its axis by 23 1/2 degrees. So Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. We have an equinox twice a year – spring and fall – when the tilt of the Earth’s axis and Earth’s orbit around the sun combine in such a way that the axis is inclined neither away from nor toward the sun.

Here are satellite views of Earth on the solstices and equinoxes, via NASA Earth Observatory.

Things change fast around the equinoxes

Since Earth never stops moving around the sun, the position of the sunrise and sunset – and the days of approximately equal sunlight and night – will change quickly.

The video below was the Astronomy Picture of the Day for March 19, 2014. APOD explained:

At an equinox, the Earth’s terminator – the dividing line between day and night – becomes vertical and connects the North and South Poles. The time-lapse video [below] demonstrates this by displaying an entire year on planet Earth in 12 seconds. From geosynchronous orbit, the Meteosat satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical.

As the Earth revolved around the sun, the terminator was seen to tilt in a way that provides less daily sunlight to the Northern Hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the Southern Hemisphere and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken – and will take – around the sun.

The equinox is an event that takes place in Earth’s orbit around the sun. Image via National Weather Service/ weather.gov.

Where are signs of the March equinox in nature?

Everywhere! Forget about the weather for a moment, and think only about daylight. In terms of daylight, the knowledge that spring is here – and summer is coming – permeates all of nature on the northern half of Earth’s globe.

Notice the arc of the sun across the sky each day. You’ll find that it’s shifting toward the north. Responding to the change in daylight, birds and butterflies are migrating back northward, too, along with the path of the sun.

The longer days do bring with them warmer weather. People are leaving their winter coats at home. Trees are budding, and plants are beginning a new cycle of growth. In many places, spring flowers are beginning to bloom.

Meanwhile, in the Southern Hemisphere, the days are getting shorter and nights longer. A chill is in the air. Fall is here, and winter is coming!

Bottom line: The 2024 March equinox falls March 20 at 3:06 UTC. So many parts of the world will see the equinox arrive on March 19. What is an equinox? How do we experience it on Earth? All you need to know, here.

The post March equinox 2024: All you need to know first appeared on EarthSky.

from EarthSky https://ift.tt/r7FmfMe