Northern Cross: Backbone of Milky Way

Northern Cross, with bright star Deneb at the top of the Cross, on a November evening. Image via AstroBob.

The Northern Cross is a clipped version of the constellation Cygnus the Swan, and is really an asterism – a pattern of stars that is not a recognized constellation. However, most people have an easier time making out the Northern Cross than they do Cygnus the Swan.

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The Northern Cross is an asterism, or noticeable pattern of stars. It’s within a true constellation – Cygnus the Swan. The Northern Cross and Swan pattern are inside a larger asterism, consisting of three bright stars, called the Summer Triangle. Image via Bob Mohler.

Northern Cross and Summer Triangle. Image via Susan Jensen.

How to find the Northern Cross. The first step to locating the Northern Cross (or Cygnus the Swan) is to find the Northern Cross’ most brilliant star, Deneb. Deneb marks the top of the Northern Cross. Deneb is perhaps just as well known for being one the three brilliant stars of the Summer Triangle, along with the even brighter stars Vega and Altair. Knowing the three stars of the Summer Triangle gives you good footing for locating the Northern Cross, which is embedded within the Summer Triangle asterism.

Roughly halfway between Altair to Vega, and somewhat offset toward Deneb, look for the brightest star in that part of the sky. That’s Albireo. Although a modestly bright star, Albireo is easy to see on a clear, dark night. Since there are no similarly bright stars near Albireo, it is fairly easy to find. Once you locate Deneb and Albireo, you’re only a hop and a skip away from piecing together the Northern Cross.

The Northern Cross, a clipped version of the constellation Cygnus the Swan. Image via Janne/ Flickr.

Backbone of Milky Way. The Northern Cross serves to point out the Milky Way – the luminescent river of stars passing through the Northern Cross and stretching all across the sky.

You need a clear, dark sky to see this hazy swath of sky, whose “haze” is really myriad stars. But it’s a sight well worth pursuing. The Milky Way band we see stretched across our sky is an edgewise view into the disk of our galaxy, the flat part of the galaxy where nearly all the visible stars are.

Keep in mind, though, that all the stars outside this band visible to your unaided eye still belong to our home galaxy, the Milky Way.

When you look at the Northern Cross, you’re looking directly into the Milky Way disk, where the soft glow of millions of stars glazes over the heavens. In fact, the galactic plane (equator) runs right through the Northern Cross, encircling the sky above and below the horizon.

On some clear, dark night, use binoculars and the Northern Cross to enjoy the star fields, star clusters and nebulae that abound within the disk of the Milky Way galaxy!

Image via thegreatlandoni/Flickr.

Northern Cross as a marker of seasons. As seen from mid-northern latitudes, the Northern Cross is out for at least part of the night all year around. It’s out all night in summer. On Northern Hemisphere summer nights, the Northern Cross shines in the east at nightfall, sweeps high overhead after midnight, and swings to the west by daybreak. By the time northern autumn arrives, the Northern Cross is still out from nightfall till midnight, but it appears high overhead at evening and sets in the northwest after midnight. When winter comes, the Northern cross is standing upright over your northwest horizon.

When you see the Northern Cross in the east on summer evenings, it’s sideways to the horizon. On autumn evenings, the Northern Cross beams high overhead but runs diagonally across the sky. On a winter evening, this wondrous star formation stands vertically to the horizon!

Bottom line: The Northern Cross is an “asterism” or recognizable pattern of stars, part of the constellation Cygnus the Swan. How to find it in your sky.

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Northern Cross, with bright star Deneb at the top of the Cross, on a November evening. Image via AstroBob.

The Northern Cross is a clipped version of the constellation Cygnus the Swan, and is really an asterism – a pattern of stars that is not a recognized constellation. However, most people have an easier time making out the Northern Cross than they do Cygnus the Swan.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

The Northern Cross is an asterism, or noticeable pattern of stars. It’s within a true constellation – Cygnus the Swan. The Northern Cross and Swan pattern are inside a larger asterism, consisting of three bright stars, called the Summer Triangle. Image via Bob Mohler.

Northern Cross and Summer Triangle. Image via Susan Jensen.

How to find the Northern Cross. The first step to locating the Northern Cross (or Cygnus the Swan) is to find the Northern Cross’ most brilliant star, Deneb. Deneb marks the top of the Northern Cross. Deneb is perhaps just as well known for being one the three brilliant stars of the Summer Triangle, along with the even brighter stars Vega and Altair. Knowing the three stars of the Summer Triangle gives you good footing for locating the Northern Cross, which is embedded within the Summer Triangle asterism.

Roughly halfway between Altair to Vega, and somewhat offset toward Deneb, look for the brightest star in that part of the sky. That’s Albireo. Although a modestly bright star, Albireo is easy to see on a clear, dark night. Since there are no similarly bright stars near Albireo, it is fairly easy to find. Once you locate Deneb and Albireo, you’re only a hop and a skip away from piecing together the Northern Cross.

The Northern Cross, a clipped version of the constellation Cygnus the Swan. Image via Janne/ Flickr.

Backbone of Milky Way. The Northern Cross serves to point out the Milky Way – the luminescent river of stars passing through the Northern Cross and stretching all across the sky.

You need a clear, dark sky to see this hazy swath of sky, whose “haze” is really myriad stars. But it’s a sight well worth pursuing. The Milky Way band we see stretched across our sky is an edgewise view into the disk of our galaxy, the flat part of the galaxy where nearly all the visible stars are.

Keep in mind, though, that all the stars outside this band visible to your unaided eye still belong to our home galaxy, the Milky Way.

When you look at the Northern Cross, you’re looking directly into the Milky Way disk, where the soft glow of millions of stars glazes over the heavens. In fact, the galactic plane (equator) runs right through the Northern Cross, encircling the sky above and below the horizon.

On some clear, dark night, use binoculars and the Northern Cross to enjoy the star fields, star clusters and nebulae that abound within the disk of the Milky Way galaxy!

Image via thegreatlandoni/Flickr.

Northern Cross as a marker of seasons. As seen from mid-northern latitudes, the Northern Cross is out for at least part of the night all year around. It’s out all night in summer. On Northern Hemisphere summer nights, the Northern Cross shines in the east at nightfall, sweeps high overhead after midnight, and swings to the west by daybreak. By the time northern autumn arrives, the Northern Cross is still out from nightfall till midnight, but it appears high overhead at evening and sets in the northwest after midnight. When winter comes, the Northern cross is standing upright over your northwest horizon.

When you see the Northern Cross in the east on summer evenings, it’s sideways to the horizon. On autumn evenings, the Northern Cross beams high overhead but runs diagonally across the sky. On a winter evening, this wondrous star formation stands vertically to the horizon!

Bottom line: The Northern Cross is an “asterism” or recognizable pattern of stars, part of the constellation Cygnus the Swan. How to find it in your sky.

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Watch the moon shed its shadow

Joseph Campbell wrote in his book “The Power of Myth“:

The power of life causes the snake to shed its skin, just as the moon sheds its shadow.

What did he mean by the moon shedding its shadow? For all worlds including the Earth and moon, night is a shadow. That is, when night falls on Earth, you’re standing within Earth’s shadow. Likewise, when you see a crescent moon in the evening sky – such as the one you’ll see on the evenings of July 21 to 24 – you’re looking at a slim fraction of moon’s dayside, and a larger fraction of its nightside. That nightside on the moon is its own shadow. Over those evenings, watch for the young moon to shed its shadow as seen from our earthly perspective – to show us more of its dayside and less of its nightside – as the moon grows in radiance in our sky.

The moon turned new on July 20, 2020. At that point, its shadowed side, or night side, faced Earth entirely, and the moon traveled across the sky with the sun during the day. The moon is said to be reborn – and a new lunation, or lunar cycle, is said to begin – at new moon. After new moon, the moon returns as a crescent to the evening sky. When the newly born moon makes its initial appearance in the west after sunset July 21, 2020, only the slightest sliver of sunlight will be lighting up the far edge of the moon as seen from Earth.

It’ll be easy to miss the moon after sunset July 21. For most of the world, the pale, whisker-thin lunar crescent will follow the sun beneath the horizon before nightfall (or before the end of astronomical twilight). If you’re up for the challenge, try catching the young moon with either the unaided eye or binoculars.

Day by the day, a wider and brighter crescent will appear higher up at sunset, and will stay out longer after dark.

You might also see Regulus, the brightest star in the constellation Leo the Lion, sometimes called the Lion’s Heart. This star is now heading into the sunset for another season. If you can’t see bright Regulus so near the glow of evening twilight, try sweeping with your binoculars. The moon will be closest to Regulus from our North America perspective on July 22. For your own unique perspective from your part of the world, try Stellarium-Web.

Find out the moon’s setting time in your sky via Sunset Sunrise Calendars, remembering to check the Moonrise and moonset box.

Find out when astronomical twilight ends in your sky via Sunrise Sunset Calendars, remembering to check the astronomical twilight box.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

Multazam Yazid captured the extremely young waxing moon on July 24, 2017, from Telok Kemang Observatory, Port Dickson, Malaysia. He was using a Takahashi TOA-150 telescope and a DSLR Canon 550D.

While you’re at it, enjoy the entrancing beauty of earthshine softly illuminating the nighttime side of the moon. Earthshine, which is most readily visible at the moon’s crescent phase, counts as twice-reflected sunlight, with sunlight bouncing from Earth to the moon, and then from the moon back to Earth. You know how, when it’s full moon, we on Earth see moonlight lighting up our earthly landscape? When we see a crescent moon, anyone on the moon would see a nearly full Earth. Earthlight illuminates the lunar landscape just as moonlight from a full or nearly full moon lights up our landscape.

That’s what you’re seeing when you see earthshine on a crescent moon.

Ken Christison caught a very young moon, with its dark side all aglow in earthshine, on March 31, 2014, the day after a new moon.

In space, the moon is actually always half-lit by the sun and half-covered by its own shadow. The portion of the moon’s day side or night side that’s visible from Earth depends on the ever-changing position of the moon, relative to the sun and Earth. At new moon – when the moon swings in between the Earth and sun – the moon’s nighttime side totally faces Earth; at full moon – when the moon is opposite the sun in Earth’s sky – the moon’s daytime side totally faces Earth.

A bird’s-eye view of the north side of the moon’s orbital plane finds the moon circling Earth in a counterclockwise direction. At new moon, when the moon is between the Earth and sun, the moon’s nighttime side totally faces Earth. At full moon, when the moon is opposite the sun in our sky, the moon’s daytime side totally faces Earth.

When the moon, Earth and sun make a 90 degree or right angle in space – with Earth at the vertex of this angle – then it’s either a first quarter or last quarter moon. At quarter moon, the eye perceives the moon as half-illuminated in sunshine and half-covered in the moon’s own shadow.

As the moon orbits Earth, its changing geometry with respect to the sun produces the characteristic phases. This composite image is a mosaic made from 25 individual photos of the moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. Photo copyright Fred Espenak.

Because the moon moves eastward (away from the setting sun) at the rate of about 12 degrees per day, watch for the young moon to shed its shadow as it waxes from new moon to full moon during the next two weeks.

Bottom line: Watch for the waxing crescent moon – what astronomers call a young moon – in the west after sunset on July 21 to 24, 2020.

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Joseph Campbell wrote in his book “The Power of Myth“:

The power of life causes the snake to shed its skin, just as the moon sheds its shadow.

What did he mean by the moon shedding its shadow? For all worlds including the Earth and moon, night is a shadow. That is, when night falls on Earth, you’re standing within Earth’s shadow. Likewise, when you see a crescent moon in the evening sky – such as the one you’ll see on the evenings of July 21 to 24 – you’re looking at a slim fraction of moon’s dayside, and a larger fraction of its nightside. That nightside on the moon is its own shadow. Over those evenings, watch for the young moon to shed its shadow as seen from our earthly perspective – to show us more of its dayside and less of its nightside – as the moon grows in radiance in our sky.

The moon turned new on July 20, 2020. At that point, its shadowed side, or night side, faced Earth entirely, and the moon traveled across the sky with the sun during the day. The moon is said to be reborn – and a new lunation, or lunar cycle, is said to begin – at new moon. After new moon, the moon returns as a crescent to the evening sky. When the newly born moon makes its initial appearance in the west after sunset July 21, 2020, only the slightest sliver of sunlight will be lighting up the far edge of the moon as seen from Earth.

It’ll be easy to miss the moon after sunset July 21. For most of the world, the pale, whisker-thin lunar crescent will follow the sun beneath the horizon before nightfall (or before the end of astronomical twilight). If you’re up for the challenge, try catching the young moon with either the unaided eye or binoculars.

Day by the day, a wider and brighter crescent will appear higher up at sunset, and will stay out longer after dark.

You might also see Regulus, the brightest star in the constellation Leo the Lion, sometimes called the Lion’s Heart. This star is now heading into the sunset for another season. If you can’t see bright Regulus so near the glow of evening twilight, try sweeping with your binoculars. The moon will be closest to Regulus from our North America perspective on July 22. For your own unique perspective from your part of the world, try Stellarium-Web.

Find out the moon’s setting time in your sky via Sunset Sunrise Calendars, remembering to check the Moonrise and moonset box.

Find out when astronomical twilight ends in your sky via Sunrise Sunset Calendars, remembering to check the astronomical twilight box.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

Multazam Yazid captured the extremely young waxing moon on July 24, 2017, from Telok Kemang Observatory, Port Dickson, Malaysia. He was using a Takahashi TOA-150 telescope and a DSLR Canon 550D.

While you’re at it, enjoy the entrancing beauty of earthshine softly illuminating the nighttime side of the moon. Earthshine, which is most readily visible at the moon’s crescent phase, counts as twice-reflected sunlight, with sunlight bouncing from Earth to the moon, and then from the moon back to Earth. You know how, when it’s full moon, we on Earth see moonlight lighting up our earthly landscape? When we see a crescent moon, anyone on the moon would see a nearly full Earth. Earthlight illuminates the lunar landscape just as moonlight from a full or nearly full moon lights up our landscape.

That’s what you’re seeing when you see earthshine on a crescent moon.

Ken Christison caught a very young moon, with its dark side all aglow in earthshine, on March 31, 2014, the day after a new moon.

In space, the moon is actually always half-lit by the sun and half-covered by its own shadow. The portion of the moon’s day side or night side that’s visible from Earth depends on the ever-changing position of the moon, relative to the sun and Earth. At new moon – when the moon swings in between the Earth and sun – the moon’s nighttime side totally faces Earth; at full moon – when the moon is opposite the sun in Earth’s sky – the moon’s daytime side totally faces Earth.

A bird’s-eye view of the north side of the moon’s orbital plane finds the moon circling Earth in a counterclockwise direction. At new moon, when the moon is between the Earth and sun, the moon’s nighttime side totally faces Earth. At full moon, when the moon is opposite the sun in our sky, the moon’s daytime side totally faces Earth.

When the moon, Earth and sun make a 90 degree or right angle in space – with Earth at the vertex of this angle – then it’s either a first quarter or last quarter moon. At quarter moon, the eye perceives the moon as half-illuminated in sunshine and half-covered in the moon’s own shadow.

As the moon orbits Earth, its changing geometry with respect to the sun produces the characteristic phases. This composite image is a mosaic made from 25 individual photos of the moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. Photo copyright Fred Espenak.

Because the moon moves eastward (away from the setting sun) at the rate of about 12 degrees per day, watch for the young moon to shed its shadow as it waxes from new moon to full moon during the next two weeks.

Bottom line: Watch for the waxing crescent moon – what astronomers call a young moon – in the west after sunset on July 21 to 24, 2020.

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Epsilon Lyrae is the famous Double Double star

A photo of Epsilon Lyrae, the Double-Double star in the constellation Lyra the Harp. See how each component in this double star system is also 2 stars? Image via Nikolay Nikolov/ Wikimedia Commons.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

Epsilon Lyrae (ε Lyrae), also known as the Double-Double star, is easy to locate due to its nearness to Vega, the brightest star in the northern half of the sky. Through binoculars, what appears as one star to the unaided eye resolves into two. And through a telescope, each star in that pair resolves into two again, making four stars. In the mid-1980s, astronomers using advanced imaging techniques detected a fifth star in that system. These five stars, bound together by gravity, are about 162 light-years from us. Read more.

How to find Epsilon Lyrae. Epsilon Lyrae is wonderfully easy to find. It’s not as bright as Vega, the constellation Lyra’s brightest star.

But Vega’s brightness, plus the distinctive shape of the constellation Lyra, can help you spot Epsilon Lyrae.

A star map of Lyra showing its primary stars. Vega is represented by the large black circle, indicating its brightness relative to other stars. Epsilon Lyrae is close to it, designated by the Greek letter “epsilon” (ε). Image via IAU/ Sky & Telescope / Wikipedia.

With the eye, the gap between Vega and Epsilon Lyrae only amounts to the width of your little finger at an arm length away. As a fun bonus, you can see Vega and Epsilon Lyrae in a single binocular field.

You might also find Vega by looking for the brightest star in the famous Summer Triangle asterism. Just remember, Epsilon Lyrae, though not as bright as Vega, shines near this brighter beacon star.

From mid-northern latitudes, Epsilon Lyrae and its constellation Lyra the Harp shine for at least part of the night all year round. Epsilon Lyrae graces the nighttime from dusk until dawn on Northern Hemisphere summer nights. It’s high overhead on northern autumn evenings. In northern winter, this star appears both in the northwest sky after dusk, and then in the northeast sky before dawn. When northern spring arrives in March, Epsilon Lyrae rises before midnight, then shines for rest of the night.

Science of the Double-Double star. Although Vega and Epsilon Lyrae appear close together in the sky, they really aren’t. They simply appear that way along our line of sight. Astronomers have determined that Vega is some 25 light-years away, whereas Epsilon Lyrae is over six times farther, at about 162 light-years.

There are many multiple star systems in the sky, but Epsilon Lyrae is special because it’s so easy to find, and so satisfying to observe when it resolves as a double star through binoculars and as a pair of binary stars through a telescope.

While the widest two components of the Epsilon Lyrae system can be clearly viewed with binoculars, you may be able to barely discern them with the unaided eye under excellent sky conditions. The northern star of the pair is known as Epsilon 1 while the southern star is Epsilon 2. They’re thought to be about 10,500 times the sun-Earth distance apart and probably take over hundreds of thousands of years to orbit each other.

Through a telescope, Epsilon 1 and Epsilon 2 are revealed to be double stars. Here, Tom Kerrs posted an image on Twitter showing Epsilon 1 and Epsilon 2 resolved as binary stars.

Epsilon Lyrae (? Lyr) – the "Double Double". It's also a binary binary. In fact, one pair has a third companion, too! pic.twitter.com/j9mJs9K8oi

— Tom Kerss ??? (@tomkerss) October 3, 2015

Epsilon 1 has two components, designated A and B, separated by about 116 times the sun-Earth distance with an orbital period of about 1,800 years. Epsilon 1A is a hot star about twice the mass of the sun and Epsilon 1B is a bit cooler, about 1.6 times the sun’s mass.

Epsilon 2 has three components: the two stars visible through a telescope are hot stars about twice the mass of the sun, separated by about 121 times the sun-Earth distance, with an orbital period of about 724 years. The third star is so faint that it was only detectable using an advanced imaging technique known as speckle imaging, and not much is known about it

Epsilon Lyrae 1 is at RA: 18h 44m 20.3s, Dec: +39° 40′ 12.4″
Epsilon Lyrae 2 is at RA: 18h 44m 22.8s, Dec: +39° 36′ 45.8″

Image via daviddarling.info.

Bottom line: Epsilon Lyrae, near Vega in the constellation Lyra, is known as the Double-Double star because it appears as two stars through binoculars, and each of those are further resolved into two stars through a telescope.

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A photo of Epsilon Lyrae, the Double-Double star in the constellation Lyra the Harp. See how each component in this double star system is also 2 stars? Image via Nikolay Nikolov/ Wikimedia Commons.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

Epsilon Lyrae (ε Lyrae), also known as the Double-Double star, is easy to locate due to its nearness to Vega, the brightest star in the northern half of the sky. Through binoculars, what appears as one star to the unaided eye resolves into two. And through a telescope, each star in that pair resolves into two again, making four stars. In the mid-1980s, astronomers using advanced imaging techniques detected a fifth star in that system. These five stars, bound together by gravity, are about 162 light-years from us. Read more.

How to find Epsilon Lyrae. Epsilon Lyrae is wonderfully easy to find. It’s not as bright as Vega, the constellation Lyra’s brightest star.

But Vega’s brightness, plus the distinctive shape of the constellation Lyra, can help you spot Epsilon Lyrae.

A star map of Lyra showing its primary stars. Vega is represented by the large black circle, indicating its brightness relative to other stars. Epsilon Lyrae is close to it, designated by the Greek letter “epsilon” (ε). Image via IAU/ Sky & Telescope / Wikipedia.

With the eye, the gap between Vega and Epsilon Lyrae only amounts to the width of your little finger at an arm length away. As a fun bonus, you can see Vega and Epsilon Lyrae in a single binocular field.

You might also find Vega by looking for the brightest star in the famous Summer Triangle asterism. Just remember, Epsilon Lyrae, though not as bright as Vega, shines near this brighter beacon star.

From mid-northern latitudes, Epsilon Lyrae and its constellation Lyra the Harp shine for at least part of the night all year round. Epsilon Lyrae graces the nighttime from dusk until dawn on Northern Hemisphere summer nights. It’s high overhead on northern autumn evenings. In northern winter, this star appears both in the northwest sky after dusk, and then in the northeast sky before dawn. When northern spring arrives in March, Epsilon Lyrae rises before midnight, then shines for rest of the night.

Science of the Double-Double star. Although Vega and Epsilon Lyrae appear close together in the sky, they really aren’t. They simply appear that way along our line of sight. Astronomers have determined that Vega is some 25 light-years away, whereas Epsilon Lyrae is over six times farther, at about 162 light-years.

There are many multiple star systems in the sky, but Epsilon Lyrae is special because it’s so easy to find, and so satisfying to observe when it resolves as a double star through binoculars and as a pair of binary stars through a telescope.

While the widest two components of the Epsilon Lyrae system can be clearly viewed with binoculars, you may be able to barely discern them with the unaided eye under excellent sky conditions. The northern star of the pair is known as Epsilon 1 while the southern star is Epsilon 2. They’re thought to be about 10,500 times the sun-Earth distance apart and probably take over hundreds of thousands of years to orbit each other.

Through a telescope, Epsilon 1 and Epsilon 2 are revealed to be double stars. Here, Tom Kerrs posted an image on Twitter showing Epsilon 1 and Epsilon 2 resolved as binary stars.

Epsilon Lyrae (? Lyr) – the "Double Double". It's also a binary binary. In fact, one pair has a third companion, too! pic.twitter.com/j9mJs9K8oi

— Tom Kerss ??? (@tomkerss) October 3, 2015

Epsilon 1 has two components, designated A and B, separated by about 116 times the sun-Earth distance with an orbital period of about 1,800 years. Epsilon 1A is a hot star about twice the mass of the sun and Epsilon 1B is a bit cooler, about 1.6 times the sun’s mass.

Epsilon 2 has three components: the two stars visible through a telescope are hot stars about twice the mass of the sun, separated by about 121 times the sun-Earth distance, with an orbital period of about 724 years. The third star is so faint that it was only detectable using an advanced imaging technique known as speckle imaging, and not much is known about it

Epsilon Lyrae 1 is at RA: 18h 44m 20.3s, Dec: +39° 40′ 12.4″
Epsilon Lyrae 2 is at RA: 18h 44m 22.8s, Dec: +39° 36′ 45.8″

Image via daviddarling.info.

Bottom line: Epsilon Lyrae, near Vega in the constellation Lyra, is known as the Double-Double star because it appears as two stars through binoculars, and each of those are further resolved into two stars through a telescope.

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Dark Sky Sanctuary established in New England

Katahdin Woods and Waters National Monument. Image via John Meader/ IDA.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

Exceptionally dark skies are breathtaking. They are also becoming rare as result of light pollution. To help protect the spectacular dark skies at Katahdin Woods and Waters National Monument in Maine, this area was certified as a Dark Sky Sanctuary on May 8, 2020. This is the first such sanctuary designation in New England and along the entire eastern seaboard of the United States.

The International Dark Sky Association (IDA) launched the Dark Sky Places conservation program in 2001 to help protect areas around the world that offer stunning views of the night sky and to increase public awareness about the need to reduce light pollution. Chosen sites are awarded one of six designations, such as Dark Sky Communities that have implemented outdoor lighting ordinances for conservation purposes and Dark Sky Parks that offer educational programs to visitors. The Dark Sky Sanctuary designation is reserved for remote areas that are among the darkest in the world.

Time exposure photo of the night sky over the East Branch of the Penobscot River, at the Katahdin Woods and Waters National Monument near Patten, Maine. Image via Robert F. Bukaty/ AP/ Bangor Daily News.

Tim Hudson, superintendent at Katahdin Woods and Waters, commented on the new sanctuary designation a statement. He said:

This designation is the culmination of a long-term effort by a dedicated group of people and is an exciting event in the short history of the monument. Designation as a Dark Sky Sanctuary recognizes this incredible resource that does not [exist] in many places today in this country, much less anywhere else in New England. Experiencing the night skies here will take you back in time to the night skies first experienced by the Wabanaki 11,000 years ago and the many people who have followed in their footsteps since, including John James Audubon, Henry David Thoreau, Theodore Roosevelt, and others.

According to the Friends of Katahdin Woods and Waters, the night skies here rank as a 2 on the Bortle Scale—the scale ranges from 1 for the darkest skies to 9 for inner city skies—which means that the Milky Way can be viewed in exceptional detail at this location in Maine. The Friends of Katahdin Woods and Waters host an annual Stars Over Katahdin party for stargazers and astronomers. The 2020 Stars Over Katahdin event will feature a virtual presentation on October 15, 2020, for anyone who wishes to learn more about this remarkable place.

The International Dark Sky Association is also encouraging everyone to take night sky measurements from their hometowns this year for the Globe at Night project. The citizen science data that are being collected will enable future research projects on a variety of issues such as the effects of light pollution on wildlife and human health and trends in energy consumption costs.

Bottom line: Katahdin Woods and Waters National Monument in Maine was certified as a Dark Sky Sanctuary on May 8, 2020. This is the first such sanctuary site established in New England.

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Katahdin Woods and Waters National Monument. Image via John Meader/ IDA.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

Exceptionally dark skies are breathtaking. They are also becoming rare as result of light pollution. To help protect the spectacular dark skies at Katahdin Woods and Waters National Monument in Maine, this area was certified as a Dark Sky Sanctuary on May 8, 2020. This is the first such sanctuary designation in New England and along the entire eastern seaboard of the United States.

The International Dark Sky Association (IDA) launched the Dark Sky Places conservation program in 2001 to help protect areas around the world that offer stunning views of the night sky and to increase public awareness about the need to reduce light pollution. Chosen sites are awarded one of six designations, such as Dark Sky Communities that have implemented outdoor lighting ordinances for conservation purposes and Dark Sky Parks that offer educational programs to visitors. The Dark Sky Sanctuary designation is reserved for remote areas that are among the darkest in the world.

Time exposure photo of the night sky over the East Branch of the Penobscot River, at the Katahdin Woods and Waters National Monument near Patten, Maine. Image via Robert F. Bukaty/ AP/ Bangor Daily News.

Tim Hudson, superintendent at Katahdin Woods and Waters, commented on the new sanctuary designation a statement. He said:

This designation is the culmination of a long-term effort by a dedicated group of people and is an exciting event in the short history of the monument. Designation as a Dark Sky Sanctuary recognizes this incredible resource that does not [exist] in many places today in this country, much less anywhere else in New England. Experiencing the night skies here will take you back in time to the night skies first experienced by the Wabanaki 11,000 years ago and the many people who have followed in their footsteps since, including John James Audubon, Henry David Thoreau, Theodore Roosevelt, and others.

According to the Friends of Katahdin Woods and Waters, the night skies here rank as a 2 on the Bortle Scale—the scale ranges from 1 for the darkest skies to 9 for inner city skies—which means that the Milky Way can be viewed in exceptional detail at this location in Maine. The Friends of Katahdin Woods and Waters host an annual Stars Over Katahdin party for stargazers and astronomers. The 2020 Stars Over Katahdin event will feature a virtual presentation on October 15, 2020, for anyone who wishes to learn more about this remarkable place.

The International Dark Sky Association is also encouraging everyone to take night sky measurements from their hometowns this year for the Globe at Night project. The citizen science data that are being collected will enable future research projects on a variety of issues such as the effects of light pollution on wildlife and human health and trends in energy consumption costs.

Bottom line: Katahdin Woods and Waters National Monument in Maine was certified as a Dark Sky Sanctuary on May 8, 2020. This is the first such sanctuary site established in New England.

from EarthSky https://ift.tt/39k977V

Why it’s difficult to estimate the number of extra cancer deaths caused by service disruption during COVID-19

Every week, a new figure comes out.

And despite the fact that they’re all trying to estimate the same thing – the number of extra cancer deaths that could be caused by service disruption during the pandemic – there’s a big range. Anything from 3,300 to 60,000 so far.

That’s because estimating the impact of COVID-19 on cancer outcomes is not an easy thing to do. In fact, it’s almost impossible.

As the stats saying goes “all models are wrong, but some are useful”. And while there’s been a lot of variation in estimates so far, each serves to highlight the negative impact for people with cancer and just how important it is to get cancer services back up and running.

Because while COVID-19 has placed unimaginable stress on health services, it’s vital to provide safe services for patients so that the pandemic doesn’t also cause an increase in deaths from other conditions like cancer.

Changes across the board

“We know there is going to be an impact on cancer survival from COVID-19, and it can only be a negative impact,” says Jon Shelton, Cancer Research UK’s senior intelligence manager.

“Screening effectively stopped during the pandemic, the number of people being referred for diagnostic tests dropped massively and a lot of tests and treatments for cancer were postponed.”

Shelton says the impact of COVID-19 has been felt across the board, with certain diagnostic procedures – like endoscopies – being stopped because they were considered too risky for both patients and healthcare staff.

Cancer treatment has been affected too, with surgery disrupted the most – falling by up to 40% of what would have been expected. Some complex surgeries were cancelled because there weren’t enough ITU beds for patients after operations.

Last month, we estimated that over 2 million people in the UK were waiting for cancer screening, tests or treatment. Another estimate, but one that has fewer assumptions.

Because while all the figures so far point towards a negative impact on cancer survival in the UK, the size of the impact is difficult to predict.

“There’s still so much uncertainty across the pathway – from screening and diagnosis to treatment, monitoring and care,” says Shelton. With that level of disruption, it’s difficult to know how all the changes will add up.

To get around this challenge, some estimates have focused on a single aspect of cancer care, like surgery, with one study estimating that there would be around 10,600 excess deaths from delaying surgery for 6 months.

“We know that complex surgery has been affected, but right now we don’t have the evidence to suggest how this will affect outcomes, especially with other treatment options being used” says Shelton. “For some slow growing tumours, there may not be much difference in outcomes, but for other cancer sites, outcomes could vary much more.”

The study didn’t account for the fact that some people who would usually have surgery have had radiotherapy instead, to reduce the size of the tumour until it’s safe to operate.

Shelton says that the impact of these changes for some patients may be more to do with side effects or quality of life, rather than survival. Something that a single figure of excess deaths will never be able to encapsulate.

Missing pieces

Studies that take a broader view may also run into problems, because there’s a lot of important information that we just don’t have.

Take cancer diagnosis. We know that in some places urgent cancer referrals plummeted to around 25% of usual numbers at the peak of the pandemic, as fewer people were going to their GP with symptoms and some were reluctant to go to secondary care for further tests due to the risks of COVID-19.

While the figures are worrying, this doesn’t necessarily mean that the number of people diagnosed has fallen by the same amount, because most people who are urgently referred do not have cancer.

“It may be that the proportion of people urgently referred during COVID-19 who go on to be diagnosed with cancer is higher than usual,” says Shelton. “We won’t know the scale until we have those figures, but we do know that many patients’ diagnosis has been delayed and we need to address this urgently – a delay to diagnosis could lead to the tumour growing and even spreading, which is harder to treat.”

But even with all this information, the size of the negative impact is still difficult to predict.

“With cancer, we don’t usually wait to diagnose or treat someone – if we know someone has cancer we want them to receive the best treatment without delay, so we don’t have the evidence for what will happen if we do wait.”

Shelton says the size of the impact will also vary from cancer to cancer. “Some tumours grow quite slowly, and therefore a delay may not impact survival very much at all,” says Shelton. “Whereas for other more aggressive tumours, it could lead to the disease spreading and a much larger impact on survival.”

While it’s possible to make assumptions to fill in some of these gaps, the sheer number of unknowns mean slight changes in each can have a big effect on the final estimate.

It’s still unfolding

Finally, with the pandemic still unfolding, the true impact of COVID-19 on cancer deaths will also depend on what happens next.

“We’re seeing movement in the right direction with the health service – screening programmes are restarting and urgent cancer referrals are going up. But it will really depend on how quickly we can get services back to, and preferably better than, pre-COVID levels.”

Shelton believes it’s vital to collect as much as evidence as possible during the pandemic, to allow researchers to really understand what changes were made and the effect they had. Not only to make sure we’re prepared for potential future waves, but so we can improve cancer services in the future.

And while it’s likely we’ll not know the full impact of COVID-19 on cancer survival for many years, Shelton believes the estimates can form an important part of the discussion.

“Accurately estimating excess deaths is virtually impossible right now, but they show what could happen if certain scenarios play out. These estimates all strongly emphasise the importance of getting cancer services back on track as soon and as safely as possible, to minimise any further negative impact for people with cancer.”

We’re keen to capture the full impact on people affected by cancer. We’ve run a survey to understand more about the experiences of people across the country and how COVID-19 is affecting them.

Katie 

Read more:

• Getting cancer services back on track during COVID-19

from Cancer Research UK – Science blog https://ift.tt/2ZMpIy8

Every week, a new figure comes out.

And despite the fact that they’re all trying to estimate the same thing – the number of extra cancer deaths that could be caused by service disruption during the pandemic – there’s a big range. Anything from 3,300 to 60,000 so far.

That’s because estimating the impact of COVID-19 on cancer outcomes is not an easy thing to do. In fact, it’s almost impossible.

As the stats saying goes “all models are wrong, but some are useful”. And while there’s been a lot of variation in estimates so far, each serves to highlight the negative impact for people with cancer and just how important it is to get cancer services back up and running.

Because while COVID-19 has placed unimaginable stress on health services, it’s vital to provide safe services for patients so that the pandemic doesn’t also cause an increase in deaths from other conditions like cancer.

Changes across the board

“We know there is going to be an impact on cancer survival from COVID-19, and it can only be a negative impact,” says Jon Shelton, Cancer Research UK’s senior intelligence manager.

“Screening effectively stopped during the pandemic, the number of people being referred for diagnostic tests dropped massively and a lot of tests and treatments for cancer were postponed.”

Shelton says the impact of COVID-19 has been felt across the board, with certain diagnostic procedures – like endoscopies – being stopped because they were considered too risky for both patients and healthcare staff.

Cancer treatment has been affected too, with surgery disrupted the most – falling by up to 40% of what would have been expected. Some complex surgeries were cancelled because there weren’t enough ITU beds for patients after operations.

Last month, we estimated that over 2 million people in the UK were waiting for cancer screening, tests or treatment. Another estimate, but one that has fewer assumptions.

Because while all the figures so far point towards a negative impact on cancer survival in the UK, the size of the impact is difficult to predict.

“There’s still so much uncertainty across the pathway – from screening and diagnosis to treatment, monitoring and care,” says Shelton. With that level of disruption, it’s difficult to know how all the changes will add up.

To get around this challenge, some estimates have focused on a single aspect of cancer care, like surgery, with one study estimating that there would be around 10,600 excess deaths from delaying surgery for 6 months.

“We know that complex surgery has been affected, but right now we don’t have the evidence to suggest how this will affect outcomes, especially with other treatment options being used” says Shelton. “For some slow growing tumours, there may not be much difference in outcomes, but for other cancer sites, outcomes could vary much more.”

The study didn’t account for the fact that some people who would usually have surgery have had radiotherapy instead, to reduce the size of the tumour until it’s safe to operate.

Shelton says that the impact of these changes for some patients may be more to do with side effects or quality of life, rather than survival. Something that a single figure of excess deaths will never be able to encapsulate.

Missing pieces

Studies that take a broader view may also run into problems, because there’s a lot of important information that we just don’t have.

Take cancer diagnosis. We know that in some places urgent cancer referrals plummeted to around 25% of usual numbers at the peak of the pandemic, as fewer people were going to their GP with symptoms and some were reluctant to go to secondary care for further tests due to the risks of COVID-19.

While the figures are worrying, this doesn’t necessarily mean that the number of people diagnosed has fallen by the same amount, because most people who are urgently referred do not have cancer.

“It may be that the proportion of people urgently referred during COVID-19 who go on to be diagnosed with cancer is higher than usual,” says Shelton. “We won’t know the scale until we have those figures, but we do know that many patients’ diagnosis has been delayed and we need to address this urgently – a delay to diagnosis could lead to the tumour growing and even spreading, which is harder to treat.”

But even with all this information, the size of the negative impact is still difficult to predict.

“With cancer, we don’t usually wait to diagnose or treat someone – if we know someone has cancer we want them to receive the best treatment without delay, so we don’t have the evidence for what will happen if we do wait.”

Shelton says the size of the impact will also vary from cancer to cancer. “Some tumours grow quite slowly, and therefore a delay may not impact survival very much at all,” says Shelton. “Whereas for other more aggressive tumours, it could lead to the disease spreading and a much larger impact on survival.”

While it’s possible to make assumptions to fill in some of these gaps, the sheer number of unknowns mean slight changes in each can have a big effect on the final estimate.

It’s still unfolding

Finally, with the pandemic still unfolding, the true impact of COVID-19 on cancer deaths will also depend on what happens next.

“We’re seeing movement in the right direction with the health service – screening programmes are restarting and urgent cancer referrals are going up. But it will really depend on how quickly we can get services back to, and preferably better than, pre-COVID levels.”

Shelton believes it’s vital to collect as much as evidence as possible during the pandemic, to allow researchers to really understand what changes were made and the effect they had. Not only to make sure we’re prepared for potential future waves, but so we can improve cancer services in the future.

And while it’s likely we’ll not know the full impact of COVID-19 on cancer survival for many years, Shelton believes the estimates can form an important part of the discussion.

“Accurately estimating excess deaths is virtually impossible right now, but they show what could happen if certain scenarios play out. These estimates all strongly emphasise the importance of getting cancer services back on track as soon and as safely as possible, to minimise any further negative impact for people with cancer.”

We’re keen to capture the full impact on people affected by cancer. We’ve run a survey to understand more about the experiences of people across the country and how COVID-19 is affecting them.

Katie 

Read more:

• Getting cancer services back on track during COVID-19

from Cancer Research UK – Science blog https://ift.tt/2ZMpIy8

Looks like Venus has dozens of active volcanoes

On Venus, ring-like structures known as coronae dot the surface of the planet. They’re thought to provide evidence of a warm interior and for ongoing geologic activity. In the global map of Venus above, the 37 coronae determined to be active in the new study appear in red, and inactive coronae appear in white. Image via Anna Gülcher/ University of Maryland.

Researchers at the University of Maryland and the Institute of Geophysics at ETH Zurich, Switzerland, announced today (July 20, 2020) that their new new 3D model of cloud-covered Venus identifies 37 recently active volcanic structures. They said their study “provides some of the best evidence yet” that Venus is today a geologically active world. The peer-reviewed journal Nature Geoscience published these scientists’ work today. Laurent Montési, a professor of geology at UMD and co-author of the research paper, said:

This is the first time we are able to point to specific structures and say ‘Look, this is not an ancient volcano but one that is active today, dormant perhaps, but not dead.’ This study significantly changes the view of Venus from a mostly inactive planet to one whose interior is still churning and can feed many active volcanoes.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

A 3D rendition of 2 coronae observed on Venus’ surface. The ringlike structures are formed when hot material from deep inside Venus rises through the planet’s mantle and erupts through its crust. The black line represents a gap in the data. Image via Laurent Montési/ University of Maryland.

A statement from University of Maryland explained:

Scientists have known for some time that Venus has a younger surface than planets like Mars and Mercury, which have cold interiors. Evidence of a warm interior and geologic activity dots the surface of the planet in the form of ring-like structures known as coronae, which form when plumes of hot material deep inside the planet rise through the mantle layer and crust. This is similar to the way mantle plumes formed the volcanic Hawaiian Islands.

But it was thought that the coronae on Venus were probably signs of ancient activity, and that Venus had cooled enough to slow geological activity in the planet’s interior and harden the crust so much that any warm material from deep inside would not be able to puncture through.

In addition, the exact processes by which mantle plumes formed coronae on Venus and the reasons for variation among coronae have been matters for debate.

In the new study, the researchers used numerical models of thermomechanical activity beneath the surface of Venus to create high-resolution, 3D simulations of coronae formation. Their simulations provide a more detailed view of the process than ever before.

The results helped Montési and his colleagues identify features that are present only in recently active coronae. The team was then able to match those features to those observed on the surface of Venus, revealing that some of the variation in coronae across the planet represents different stages of geological development.

The study provides the first evidence that coronae on Venus are still evolving, indicating that the interior of the planet is still churning.

Anna Gülcher is a Ph.D. student in the Geophysical Fluid Dynamics group at ETH Zürich and lead author of the new study.

Montési added:

The improved degree of realism in these models over previous studies makes it possible to identify several stages in corona evolution and define diagnostic geological features present only at currently active coronae. We are able to tell that at least 37 coronae have been very recently active.

The active coronae on Venus are clustered in a handful of locations, which suggests areas where the planet is most active, providing clues to the workings of the planet’s interior. These results may help identify target areas where geologic instruments should be placed on future missions to Venus, such as Europe’s EnVision mission, scheduled to launch in 2032.

We’ve known about volcanic mountains on Venus for some time. Here is Maat Mons, a massive Venusian shield volcano. It’s the second-highest mountain – and the highest volcano – on Venus, rising some 5 miles (8 km) high. This perspective view is based on radar images from the Magellan spacecraft, which orbited Venus from 1990 to 1994. Maat Mons is not one of the locations evaluated in the new study, by the way. This structure on Venus be inactive or active, but the new study doesn’t address that question. In addition, there could be additional locations of current activity on Venus not pinpointed by the new study. Image via NASA Photo Journal.

Bottom line: A new 3D model of cloud-covered Venus provides evidence that this neighboring planet has active volcanoes.

Source: Corona structures driven by plume-lithosphere interactions and evidence for ongoing plume activity on Venus

Via University of Maryland

from EarthSky https://ift.tt/3hhO9JK

On Venus, ring-like structures known as coronae dot the surface of the planet. They’re thought to provide evidence of a warm interior and for ongoing geologic activity. In the global map of Venus above, the 37 coronae determined to be active in the new study appear in red, and inactive coronae appear in white. Image via Anna Gülcher/ University of Maryland.

Researchers at the University of Maryland and the Institute of Geophysics at ETH Zurich, Switzerland, announced today (July 20, 2020) that their new new 3D model of cloud-covered Venus identifies 37 recently active volcanic structures. They said their study “provides some of the best evidence yet” that Venus is today a geologically active world. The peer-reviewed journal Nature Geoscience published these scientists’ work today. Laurent Montési, a professor of geology at UMD and co-author of the research paper, said:

This is the first time we are able to point to specific structures and say ‘Look, this is not an ancient volcano but one that is active today, dormant perhaps, but not dead.’ This study significantly changes the view of Venus from a mostly inactive planet to one whose interior is still churning and can feed many active volcanoes.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

A 3D rendition of 2 coronae observed on Venus’ surface. The ringlike structures are formed when hot material from deep inside Venus rises through the planet’s mantle and erupts through its crust. The black line represents a gap in the data. Image via Laurent Montési/ University of Maryland.

A statement from University of Maryland explained:

Scientists have known for some time that Venus has a younger surface than planets like Mars and Mercury, which have cold interiors. Evidence of a warm interior and geologic activity dots the surface of the planet in the form of ring-like structures known as coronae, which form when plumes of hot material deep inside the planet rise through the mantle layer and crust. This is similar to the way mantle plumes formed the volcanic Hawaiian Islands.

But it was thought that the coronae on Venus were probably signs of ancient activity, and that Venus had cooled enough to slow geological activity in the planet’s interior and harden the crust so much that any warm material from deep inside would not be able to puncture through.

In addition, the exact processes by which mantle plumes formed coronae on Venus and the reasons for variation among coronae have been matters for debate.

In the new study, the researchers used numerical models of thermomechanical activity beneath the surface of Venus to create high-resolution, 3D simulations of coronae formation. Their simulations provide a more detailed view of the process than ever before.

The results helped Montési and his colleagues identify features that are present only in recently active coronae. The team was then able to match those features to those observed on the surface of Venus, revealing that some of the variation in coronae across the planet represents different stages of geological development.

The study provides the first evidence that coronae on Venus are still evolving, indicating that the interior of the planet is still churning.

Anna Gülcher is a Ph.D. student in the Geophysical Fluid Dynamics group at ETH Zürich and lead author of the new study.

Montési added:

The improved degree of realism in these models over previous studies makes it possible to identify several stages in corona evolution and define diagnostic geological features present only at currently active coronae. We are able to tell that at least 37 coronae have been very recently active.

The active coronae on Venus are clustered in a handful of locations, which suggests areas where the planet is most active, providing clues to the workings of the planet’s interior. These results may help identify target areas where geologic instruments should be placed on future missions to Venus, such as Europe’s EnVision mission, scheduled to launch in 2032.

We’ve known about volcanic mountains on Venus for some time. Here is Maat Mons, a massive Venusian shield volcano. It’s the second-highest mountain – and the highest volcano – on Venus, rising some 5 miles (8 km) high. This perspective view is based on radar images from the Magellan spacecraft, which orbited Venus from 1990 to 1994. Maat Mons is not one of the locations evaluated in the new study, by the way. This structure on Venus be inactive or active, but the new study doesn’t address that question. In addition, there could be additional locations of current activity on Venus not pinpointed by the new study. Image via NASA Photo Journal.

Bottom line: A new 3D model of cloud-covered Venus provides evidence that this neighboring planet has active volcanoes.

Source: Corona structures driven by plume-lithosphere interactions and evidence for ongoing plume activity on Venus

Via University of Maryland

from EarthSky https://ift.tt/3hhO9JK

Insights on Saturn at opposition

View larger. | Here is Saturn ascending in the east on the night of its opposition – July 20, 2020 – shortly after sunset, just behind Jupiter, which passed the anti-sun point (its opposition) on July 14. Chart via Guy Ottewell’s blog.

Originally published July 19, 2020, at Guy Ottewell’s blog. Reprinted with permission. Don’t miss Guy’s new book : Venus, A Longer View.

Planet Six – Saturn, long believed to be the outermost planet of our solar system – will be at opposition on July 20, 2020.

The moment of the opposition is July 22, 20 hours UTC – no, July 20, 22 UTC! This is the sort of trap that catches arithmophobes like me, who are liable to show up at 8 on the 9th instead of 9 on the 8th.

And the illustration below shows a space view: a survey of Saturn’s oppositions all around its nearly 30-year orbit, like the picture we showed for Jupiter.

If you look at the Jupiter and Saturn pictures in alternation, remember that the Saturn picture is at a smaller scale, because it reaches out farther.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

View larger. | Saturn’s oppositions all around its 29.5-year orbit. The constellation boundaries are painted on an imaginary sphere of radius 11 astronomical units or AU (sun-Earth distances). Saturn’s mean distance from the Sun is 9.5 AU. The sightlines from Earth to Saturn are at the dates of opposition each year. Remember that the dates of Saturn’s oposition are driven primarily by Earth’s motion, in its smaller, faster orbit around the sun. Illustration via Guy Ottewell’s blog.

We think of Jupiter as going around the sun in 12 years and Saturn in 30, so that Jupiter spends one year in each zodiacal constellation, and Saturn spends two and a half years in each. But, more exactly, each of those planets’ orbital periods is a bit shorter than those simple ideals. Jupiter’s is 11.85, and Saturn’s is 29.5.

Thus Jupiter’s course of 2020 is slightly overlapped by its course of 12 years later (2031). And Saturn’s course of 2020 is half overlapped by its course of 30 years later (2049).

Believe me, an arithmophobe has to think carefully to get even those additions right! It would be easier if we were now in the year 2001.

Each successive year, Earth has to go around an extra part of a month to overtake Saturn; so the oppositions move later in the year, until they skip a year. One falls near the end of 2032, so there is none in 2033 and the next is in early 2034.

And, the astronomical constellations being irregular, Saturn has (in this cycle) no opposition in Scorpius and two in Ophiuchus.

In the illustration above, the globes representing Saturn are exaggerated 100 times in size. Stalks from them are perpendicular to the ecliptic plane.

Saturn was at its descending node through the plane only this year, in February, so at opposition it really is almost exactly opposite to the sun – barely south of the anti-sun point. It will ascend through the plane half an orbit later, in June 2034, so that the opposition in January of that year will also be only just south of the ecliptic.

At the present opposite, Saturn’s magnitude is 0.1; it can be as bright as -0.5, as in 2031 and 2032, or as dim as 0.6, as in 2024, 2025, and 2039.

Bottom line: Astronomer Guy Ottewell offers his insights – and chart-making skills – to you during this 2020 opposition of our solar system’s golden and glorious planet of the rings, Saturn.

Via Guy Ottewell

from EarthSky https://ift.tt/2WEjdLU

View larger. | Here is Saturn ascending in the east on the night of its opposition – July 20, 2020 – shortly after sunset, just behind Jupiter, which passed the anti-sun point (its opposition) on July 14. Chart via Guy Ottewell’s blog.

Originally published July 19, 2020, at Guy Ottewell’s blog. Reprinted with permission. Don’t miss Guy’s new book : Venus, A Longer View.

Planet Six – Saturn, long believed to be the outermost planet of our solar system – will be at opposition on July 20, 2020.

The moment of the opposition is July 22, 20 hours UTC – no, July 20, 22 UTC! This is the sort of trap that catches arithmophobes like me, who are liable to show up at 8 on the 9th instead of 9 on the 8th.

And the illustration below shows a space view: a survey of Saturn’s oppositions all around its nearly 30-year orbit, like the picture we showed for Jupiter.

If you look at the Jupiter and Saturn pictures in alternation, remember that the Saturn picture is at a smaller scale, because it reaches out farther.

EarthSky’s yearly crowd-funding campaign is in progress. In 2020, we are donating 8.5% to No Kids Hungry. Please donate to help us keep going, and help feed a kid!

View larger. | Saturn’s oppositions all around its 29.5-year orbit. The constellation boundaries are painted on an imaginary sphere of radius 11 astronomical units or AU (sun-Earth distances). Saturn’s mean distance from the Sun is 9.5 AU. The sightlines from Earth to Saturn are at the dates of opposition each year. Remember that the dates of Saturn’s oposition are driven primarily by Earth’s motion, in its smaller, faster orbit around the sun. Illustration via Guy Ottewell’s blog.

We think of Jupiter as going around the sun in 12 years and Saturn in 30, so that Jupiter spends one year in each zodiacal constellation, and Saturn spends two and a half years in each. But, more exactly, each of those planets’ orbital periods is a bit shorter than those simple ideals. Jupiter’s is 11.85, and Saturn’s is 29.5.

Thus Jupiter’s course of 2020 is slightly overlapped by its course of 12 years later (2031). And Saturn’s course of 2020 is half overlapped by its course of 30 years later (2049).

Believe me, an arithmophobe has to think carefully to get even those additions right! It would be easier if we were now in the year 2001.

Each successive year, Earth has to go around an extra part of a month to overtake Saturn; so the oppositions move later in the year, until they skip a year. One falls near the end of 2032, so there is none in 2033 and the next is in early 2034.

And, the astronomical constellations being irregular, Saturn has (in this cycle) no opposition in Scorpius and two in Ophiuchus.

In the illustration above, the globes representing Saturn are exaggerated 100 times in size. Stalks from them are perpendicular to the ecliptic plane.

Saturn was at its descending node through the plane only this year, in February, so at opposition it really is almost exactly opposite to the sun – barely south of the anti-sun point. It will ascend through the plane half an orbit later, in June 2034, so that the opposition in January of that year will also be only just south of the ecliptic.

At the present opposite, Saturn’s magnitude is 0.1; it can be as bright as -0.5, as in 2031 and 2032, or as dim as 0.6, as in 2024, 2025, and 2039.

Bottom line: Astronomer Guy Ottewell offers his insights – and chart-making skills – to you during this 2020 opposition of our solar system’s golden and glorious planet of the rings, Saturn.

Via Guy Ottewell

from EarthSky https://ift.tt/2WEjdLU