Cassiopeia, Queen of the north

On these December evenings, turn toward the northern sky and see its famous constellation Cassiopeia the Queen. In early December, Cassiopeia swings directly over Polaris, the North Star, at roughly 7 p.m. local clock time. Cassiopeia – sometimes called The Lady of the Chair – is famous for having the shape of a telltale W or M. You will find this configuration of stars as a starlit M whenever she reigns highest in the sky, hovering over Polaris.

At this time of year, Cassiopeia can also be seen from tropical and subtropical latitudes in the Southern Hemisphere. From there, the constellation appears low in the north around 7 to 8 p.m. on early December evenings. As for Polaris … from the Southern Hemisphere, it’s below the horizon.

Because Cassiopeia returns to the same spot in the sky about four minutes earlier with each passing day, or 1/2 hour earlier with each passing week, look for Cassiopeia to be at her high point over Polaris, the North Star, around 6 p.m. in early January.

Zefri Besar in Brunei Darussalam caught Cassiopeia and the Andromeda galaxy in November 2016, using a DSLR camera and 50mm lens. Notice that – no matter how they are oriented in the sky – the deeper “V” of Cassiopeia points toward the galaxy.

From a dark country sky, you’ll see that Cassiopeia sits atop the luminous band of stars known as the Milky Way. Arching from horizon to horizon, this soft-glowing boulevard of stars represents an edgewise view into the flat disk of our own Milky Way galaxy. When Cassiopeia climbs above Polaris, the North Star, on these dark winter evenings, note that this hazy belt of stars that we call the Milky Way extends through the Northern Cross in the western sky and past Orion the Hunter in your eastern sky.

This Milky Way is fainter than the glorious broad band of the Milky Way we see in a Northern Hemisphere summer or Southern Hemisphere winter. That’s because, at the opposite side of the year, we are looking toward the star-rich center of the galaxy. On these December nights, we are looking toward the galaxy’s outer edge, not the center.

The famous Double Cluster in the constellation Perseus is not far from Cassiopeia on the sky’s dome. This chart shows how to use the W or M shape of Cassiopeia to find the Double Cluster. To appreciate the clusters fully, look with your binoculars in a dark sky! More about the Double Cluster here.

As the night marches onward, Cassiopeia – like the hour hand of a clock – circles around the North Star, though in a counter-clockwise direction.

By dawn, you will find Cassiopeia has swept down in the northwest – to a point below the North Star. At that time, if you’re at a southerly latitude, such as the far south U.S., you might not be able to see Cassiopeia. The constellation might be below your horizon. But if you’re located at a latitude like those in the northern U.S., you will still see Cassiopeia sitting on or near your northern horizon.

Look northward on these cold December evenings to see Queen Cassiopeia sitting proudly on her throne, atop the northern terminus of the Milky Way!

Queen Cassiopeia, aka The Lady of the Chair. Image via Hubble Source.

Bottom line: Watch for Cassiopeia the Queen on these December evenings. The constellation is shaped like an M or W. You’ll find Cassiopeia in the northeast at nightfall, sweeping higher in the north as evening progresses.

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On these December evenings, turn toward the northern sky and see its famous constellation Cassiopeia the Queen. In early December, Cassiopeia swings directly over Polaris, the North Star, at roughly 7 p.m. local clock time. Cassiopeia – sometimes called The Lady of the Chair – is famous for having the shape of a telltale W or M. You will find this configuration of stars as a starlit M whenever she reigns highest in the sky, hovering over Polaris.

At this time of year, Cassiopeia can also be seen from tropical and subtropical latitudes in the Southern Hemisphere. From there, the constellation appears low in the north around 7 to 8 p.m. on early December evenings. As for Polaris … from the Southern Hemisphere, it’s below the horizon.

Because Cassiopeia returns to the same spot in the sky about four minutes earlier with each passing day, or 1/2 hour earlier with each passing week, look for Cassiopeia to be at her high point over Polaris, the North Star, around 6 p.m. in early January.

Zefri Besar in Brunei Darussalam caught Cassiopeia and the Andromeda galaxy in November 2016, using a DSLR camera and 50mm lens. Notice that – no matter how they are oriented in the sky – the deeper “V” of Cassiopeia points toward the galaxy.

From a dark country sky, you’ll see that Cassiopeia sits atop the luminous band of stars known as the Milky Way. Arching from horizon to horizon, this soft-glowing boulevard of stars represents an edgewise view into the flat disk of our own Milky Way galaxy. When Cassiopeia climbs above Polaris, the North Star, on these dark winter evenings, note that this hazy belt of stars that we call the Milky Way extends through the Northern Cross in the western sky and past Orion the Hunter in your eastern sky.

This Milky Way is fainter than the glorious broad band of the Milky Way we see in a Northern Hemisphere summer or Southern Hemisphere winter. That’s because, at the opposite side of the year, we are looking toward the star-rich center of the galaxy. On these December nights, we are looking toward the galaxy’s outer edge, not the center.

The famous Double Cluster in the constellation Perseus is not far from Cassiopeia on the sky’s dome. This chart shows how to use the W or M shape of Cassiopeia to find the Double Cluster. To appreciate the clusters fully, look with your binoculars in a dark sky! More about the Double Cluster here.

As the night marches onward, Cassiopeia – like the hour hand of a clock – circles around the North Star, though in a counter-clockwise direction.

By dawn, you will find Cassiopeia has swept down in the northwest – to a point below the North Star. At that time, if you’re at a southerly latitude, such as the far south U.S., you might not be able to see Cassiopeia. The constellation might be below your horizon. But if you’re located at a latitude like those in the northern U.S., you will still see Cassiopeia sitting on or near your northern horizon.

Look northward on these cold December evenings to see Queen Cassiopeia sitting proudly on her throne, atop the northern terminus of the Milky Way!

Queen Cassiopeia, aka The Lady of the Chair. Image via Hubble Source.

Bottom line: Watch for Cassiopeia the Queen on these December evenings. The constellation is shaped like an M or W. You’ll find Cassiopeia in the northeast at nightfall, sweeping higher in the north as evening progresses.

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A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!

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Don’t miss these cyclones on Jupiter, and more

Jupiter’s south pole as seen from the Juno spacecraft on November 4, 2019. These swirling spots are cyclones at Jupiter’s pole. The whole hexagonal arrangement of cyclones is large enough to dwarf the Earth. The central cyclone can be compared to the continental U.S. The smallest one, in the lower right – a new one, seen for the first time in November – can be compared to Texas. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

The Juno spacecraft – which has been orbiting the giant planet Jupiter since July of 2016 – acquires close-up images of the planet at every perijove, or closest point to Jupiter. That happens about every 53 days. The batch of images acquired by the craft in early November, when it swung to within 2,175 miles (3,500 km) of the cloudtops at Jupiter’s south pole, are particularly mind-blowing. The big news for the November flyby … the craft discovered that Jupiter’s south pole has seven large, well defined cyclones now, instead of the six seen previously. These cyclones appear in a hexagonal (six-sided) pattern at Jupiter’s pole, rather than the pentagonal (five-sided) pattern seen previously. A statement from NASA explained:

When Juno first arrived at Jupiter in July 2016, its infrared and visible-light cameras discovered giant cyclones encircling the planet’s poles – nine in the north and six in the south. Were they, like their Earthly siblings, a transient phenomenon, taking only weeks to develop and then ebb? Or could these cyclones, each nearly as wide as the continental U.S., be more permanent fixtures?

With each flyby, the data reinforced the idea that five windstorms were swirling in a pentagonal pattern around a central storm at the south pole and that the system seemed stable. None of the six storms showed signs of yielding to allow other cyclones to join in …

Then, during Juno’s 22nd science pass, a new, smaller cyclone churned to life and joined the fray.

Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome, said:

Data from Juno’s Jovian Infrared Auroral Mapper [JIRAM] instrument indicates we went from a pentagon of cyclones surrounding one at the center to a hexagonal arrangement.

This new addition is smaller in stature than its six more established cyclonic brothers: It’s about the size of Texas.

Maybe JIRAM data from future flybys will show the cyclone growing to the same size as its neighbors.

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Jupiter’s pentagon turns hexagon. In this annotated infrared image, 6 cyclones form a hexagonal pattern around a central cyclone at Jupiter’s south pole. That’s in contrast to the 5 cyclones in a pentagonal shape seen previously. NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

To give some sense of the immense scale of cyclones arranged in a hexagonal pattern at Jupiter’s south pole, an outline of the continental United States is superimposed over the central cyclone and an outline of Texas is superimposed over the newest cyclone. The hexagonal arrangement of the cyclones is large enough to dwarf the Earth. This JIRAM image was obtained during the 23rd science pass of the Juno spacecraft over Jupiter, on November 4, 2019. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

NASA said the flyby:

… also marked a victory for the mission team, whose innovative measures kept the solar-powered spacecraft clear of what could have been a mission-ending eclipse.

To understand what happened, you have to go back to Juno’s entry into orbit around Jupiter on July 4, 2016. It was meant to enter an initial 53-day orbit, then reduce the size of its orbit a few months later, in order to shorten the period between science flybys to every 14 days. But the project team recommended to NASA to forgo the main engine burn due to concerns about the spacecraft’s fuel delivery system.

Now Juno is carrying out its mission, NASA said, although it’s taking longer than originally plannned. But Juno’s longer life at Jupiter is what led to the need to avoid Jupiter’s shadow. Steve Levin, Juno project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, explained:

Ever since the day we entered orbit around Jupiter, we made sure it remained bathed in sunlight 24/7. Our navigators and engineers told us a day of reckoning was coming, when we would go into Jupiter’s shadow for about 12 hours. We knew that for such an extended period without power, our spacecraft would suffer a similar fate as the Opportunity rover, when the skies of Mars filled with dust and blocked the sun’s rays from reaching its solar panels.

View larger. | In this image, you can see a shadow on Jupiter, cast by its moon Io. Io’s shadow can be seen on Jupiter through earthly telescopes, and many pictures have been taken of it from space as well, but this is the first from such a close distance, just 8,450 miles (13,600 kilometers) above Jupiter’s cloudtops. JunoCam acquired this image on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS. Image processing by citizen scientist Tanya Oleksuik.

NASA explained that, without the sun’s rays providing power, Juno would be chilled below tested levels. The space scientists believed that – during this time – Juno’s battery cells would be drained beyond recovery. So the navigation team set devised a plan to “jump the shadow,” maneuvering the spacecraft just enough so its trajectory would miss the eclipse. NASA said:

The navigators calculated that if Juno performed a rocket burn weeks in advance of November 3, while the spacecraft was as far in its orbit from Jupiter as it gets, they could modify its trajectory enough to give the eclipse the slip. The maneuver would utilize the spacecraft’s reaction control system, which wasn’t initially intended to be used for a maneuver of this size and duration.

On September 30, at 7:46 p.m. EDT (4:46 p.m. PDT), the reaction control system burn began. It ended 10 ½ hours later. The propulsive maneuver — five times longer than any previous use of that system — changed Juno’s orbital velocity by 126 mph (203 kph) and consumed about 160 pounds (73 kilograms) of fuel.

Thirty-four days later, the spacecraft’s solar arrays continued to convert sunlight into electrons unabated as Juno prepared to scream once again over Jupiter’s cloud tops.

Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio, explained:

The combination of creativity and analytical thinking has once again paid off big time for NASA … While the team was trying to figure out how to conserve energy and keep our core heated, the engineers came up with a completely new way out of the problem: Jump Jupiter’s shadow.

It was nothing less than a navigation stroke of genius. Lo and behold, first thing out of the gate on the other side, we make another fundamental discovery.

As you read this, Juno is heading toward its next perijove on December 26, 2019. Watch for news and new images shortly after the new year dawns!

View larger. | Swirls and storms in Jupiter’s clouds. This image of a vortex on Jupiter, taken by the Juno mission camera, JunoCam, captures the amazing internal structure of the giant storm. Original image taken on November 3, 2019, at an altitude of approximately 5,300 miles (8,600 km) and a latitude of about 48 degrees north on Jupiter. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Junocam. Image processing by citizen scientists Gerald Eichstädt/ Seán Doran.

In this amazing Juno image, south is up. The original image was captured by JunoCam on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ JunoCam. Image processing by citizen scientist Prateek Sarpal, who titled this “A mind of limits, a camera of thoughts.”

Bottom line: On its last flyby close to Jupiter – on November 4, 2019 – the Juno spacecraft discovered a new small cyclone at Jupiter’s south pole.

See all the latest images from NASA’s Juno spacecraft

Via NASA

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Jupiter’s south pole as seen from the Juno spacecraft on November 4, 2019. These swirling spots are cyclones at Jupiter’s pole. The whole hexagonal arrangement of cyclones is large enough to dwarf the Earth. The central cyclone can be compared to the continental U.S. The smallest one, in the lower right – a new one, seen for the first time in November – can be compared to Texas. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

The Juno spacecraft – which has been orbiting the giant planet Jupiter since July of 2016 – acquires close-up images of the planet at every perijove, or closest point to Jupiter. That happens about every 53 days. The batch of images acquired by the craft in early November, when it swung to within 2,175 miles (3,500 km) of the cloudtops at Jupiter’s south pole, are particularly mind-blowing. The big news for the November flyby … the craft discovered that Jupiter’s south pole has seven large, well defined cyclones now, instead of the six seen previously. These cyclones appear in a hexagonal (six-sided) pattern at Jupiter’s pole, rather than the pentagonal (five-sided) pattern seen previously. A statement from NASA explained:

When Juno first arrived at Jupiter in July 2016, its infrared and visible-light cameras discovered giant cyclones encircling the planet’s poles – nine in the north and six in the south. Were they, like their Earthly siblings, a transient phenomenon, taking only weeks to develop and then ebb? Or could these cyclones, each nearly as wide as the continental U.S., be more permanent fixtures?

With each flyby, the data reinforced the idea that five windstorms were swirling in a pentagonal pattern around a central storm at the south pole and that the system seemed stable. None of the six storms showed signs of yielding to allow other cyclones to join in …

Then, during Juno’s 22nd science pass, a new, smaller cyclone churned to life and joined the fray.

Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome, said:

Data from Juno’s Jovian Infrared Auroral Mapper [JIRAM] instrument indicates we went from a pentagon of cyclones surrounding one at the center to a hexagonal arrangement.

This new addition is smaller in stature than its six more established cyclonic brothers: It’s about the size of Texas.

Maybe JIRAM data from future flybys will show the cyclone growing to the same size as its neighbors.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Jupiter’s pentagon turns hexagon. In this annotated infrared image, 6 cyclones form a hexagonal pattern around a central cyclone at Jupiter’s south pole. That’s in contrast to the 5 cyclones in a pentagonal shape seen previously. NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

To give some sense of the immense scale of cyclones arranged in a hexagonal pattern at Jupiter’s south pole, an outline of the continental United States is superimposed over the central cyclone and an outline of Texas is superimposed over the newest cyclone. The hexagonal arrangement of the cyclones is large enough to dwarf the Earth. This JIRAM image was obtained during the 23rd science pass of the Juno spacecraft over Jupiter, on November 4, 2019. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

NASA said the flyby:

… also marked a victory for the mission team, whose innovative measures kept the solar-powered spacecraft clear of what could have been a mission-ending eclipse.

To understand what happened, you have to go back to Juno’s entry into orbit around Jupiter on July 4, 2016. It was meant to enter an initial 53-day orbit, then reduce the size of its orbit a few months later, in order to shorten the period between science flybys to every 14 days. But the project team recommended to NASA to forgo the main engine burn due to concerns about the spacecraft’s fuel delivery system.

Now Juno is carrying out its mission, NASA said, although it’s taking longer than originally plannned. But Juno’s longer life at Jupiter is what led to the need to avoid Jupiter’s shadow. Steve Levin, Juno project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, explained:

Ever since the day we entered orbit around Jupiter, we made sure it remained bathed in sunlight 24/7. Our navigators and engineers told us a day of reckoning was coming, when we would go into Jupiter’s shadow for about 12 hours. We knew that for such an extended period without power, our spacecraft would suffer a similar fate as the Opportunity rover, when the skies of Mars filled with dust and blocked the sun’s rays from reaching its solar panels.

View larger. | In this image, you can see a shadow on Jupiter, cast by its moon Io. Io’s shadow can be seen on Jupiter through earthly telescopes, and many pictures have been taken of it from space as well, but this is the first from such a close distance, just 8,450 miles (13,600 kilometers) above Jupiter’s cloudtops. JunoCam acquired this image on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS. Image processing by citizen scientist Tanya Oleksuik.

NASA explained that, without the sun’s rays providing power, Juno would be chilled below tested levels. The space scientists believed that – during this time – Juno’s battery cells would be drained beyond recovery. So the navigation team set devised a plan to “jump the shadow,” maneuvering the spacecraft just enough so its trajectory would miss the eclipse. NASA said:

The navigators calculated that if Juno performed a rocket burn weeks in advance of November 3, while the spacecraft was as far in its orbit from Jupiter as it gets, they could modify its trajectory enough to give the eclipse the slip. The maneuver would utilize the spacecraft’s reaction control system, which wasn’t initially intended to be used for a maneuver of this size and duration.

On September 30, at 7:46 p.m. EDT (4:46 p.m. PDT), the reaction control system burn began. It ended 10 ½ hours later. The propulsive maneuver — five times longer than any previous use of that system — changed Juno’s orbital velocity by 126 mph (203 kph) and consumed about 160 pounds (73 kilograms) of fuel.

Thirty-four days later, the spacecraft’s solar arrays continued to convert sunlight into electrons unabated as Juno prepared to scream once again over Jupiter’s cloud tops.

Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio, explained:

The combination of creativity and analytical thinking has once again paid off big time for NASA … While the team was trying to figure out how to conserve energy and keep our core heated, the engineers came up with a completely new way out of the problem: Jump Jupiter’s shadow.

It was nothing less than a navigation stroke of genius. Lo and behold, first thing out of the gate on the other side, we make another fundamental discovery.

As you read this, Juno is heading toward its next perijove on December 26, 2019. Watch for news and new images shortly after the new year dawns!

View larger. | Swirls and storms in Jupiter’s clouds. This image of a vortex on Jupiter, taken by the Juno mission camera, JunoCam, captures the amazing internal structure of the giant storm. Original image taken on November 3, 2019, at an altitude of approximately 5,300 miles (8,600 km) and a latitude of about 48 degrees north on Jupiter. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Junocam. Image processing by citizen scientists Gerald Eichstädt/ Seán Doran.

In this amazing Juno image, south is up. The original image was captured by JunoCam on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ JunoCam. Image processing by citizen scientist Prateek Sarpal, who titled this “A mind of limits, a camera of thoughts.”

Bottom line: On its last flyby close to Jupiter – on November 4, 2019 – the Juno spacecraft discovered a new small cyclone at Jupiter’s south pole.

See all the latest images from NASA’s Juno spacecraft

Via NASA

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Next new moon is December 26

Youngest possible lunar crescent, with the moon’s age being exactly zero when this photo was taken — at the instant of new moon – 07:14 UTC on July 8, 2013. Image by Thierry Legault.

When the moon is new, it’s most nearly between the Earth and sun for any particular month. There’s a new moon about once a month, because the moon takes about a month to orbit Earth. Most of the time, the new moon passes not in front of the sun, but simply near it in our sky. That’s why, in most months, there’s no solar eclipse. In December 2019, however, an eclipse does occur. It’s an annular or “ring” eclipse – the only one of 2019 – visible from Earth’s Eastern Hemisphere.

Read more: Annular solar eclipse of December 26

The moon must be at the new phase in order for a solar eclipse to take place.

The photo of a new moon at the top of this page shows the moon as it passed near the sun on July 8, 2013. There was no eclipse that day; it was an ordinary new moon. New moons typically can’t be seen, or at least they can’t without special equipment and a lot of moon-photography experience. Thierry Legault was able to catch the photo at top – the moon at the instant it was new – because the moon that month passed to one side of the sun, and the faintest of lunar crescents was visible.

Either way – in front of the sun or just near it – on the day of new moon, the moon travels across the sky with the sun during the day, hidden in the sun’s glare.

Some people use the term new moon for a thin crescent moon visible in the west after sunset. You always see these little crescents – which set shortly after the sun – a day or two after each month’s new moon. Astronomers don’t call these little crescent moons new moons, however. In the language of astronomy, this slim crescent is called a young moon.

New moons, and young moons, are fascinating to many. The Farmer’s Almanac, for example, still offers information on gardening by the moon. And many cultures have holidays based on moon phases.

Start looking for the young moon – a slim crescent visible in the west after sunset – around August 31, 2019. Read more.

Bottom line: New moons generally can’t be seen. They cross the sky with the sun during the day. The next new moon happens on December 26 at 5:13 UTC. It will cause an annular or ring eclipse, visible from Earth’s Eastern Hemisphere.

Read more: Year’s closest new supermoon on August 30

Read more: What’s the youngest moon you can see?

Read more: 4 keys to understanding moon phases

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Youngest possible lunar crescent, with the moon’s age being exactly zero when this photo was taken — at the instant of new moon – 07:14 UTC on July 8, 2013. Image by Thierry Legault.

When the moon is new, it’s most nearly between the Earth and sun for any particular month. There’s a new moon about once a month, because the moon takes about a month to orbit Earth. Most of the time, the new moon passes not in front of the sun, but simply near it in our sky. That’s why, in most months, there’s no solar eclipse. In December 2019, however, an eclipse does occur. It’s an annular or “ring” eclipse – the only one of 2019 – visible from Earth’s Eastern Hemisphere.

Read more: Annular solar eclipse of December 26

The moon must be at the new phase in order for a solar eclipse to take place.

The photo of a new moon at the top of this page shows the moon as it passed near the sun on July 8, 2013. There was no eclipse that day; it was an ordinary new moon. New moons typically can’t be seen, or at least they can’t without special equipment and a lot of moon-photography experience. Thierry Legault was able to catch the photo at top – the moon at the instant it was new – because the moon that month passed to one side of the sun, and the faintest of lunar crescents was visible.

Either way – in front of the sun or just near it – on the day of new moon, the moon travels across the sky with the sun during the day, hidden in the sun’s glare.

Some people use the term new moon for a thin crescent moon visible in the west after sunset. You always see these little crescents – which set shortly after the sun – a day or two after each month’s new moon. Astronomers don’t call these little crescent moons new moons, however. In the language of astronomy, this slim crescent is called a young moon.

New moons, and young moons, are fascinating to many. The Farmer’s Almanac, for example, still offers information on gardening by the moon. And many cultures have holidays based on moon phases.

Start looking for the young moon – a slim crescent visible in the west after sunset – around August 31, 2019. Read more.

Bottom line: New moons generally can’t be seen. They cross the sky with the sun during the day. The next new moon happens on December 26 at 5:13 UTC. It will cause an annular or ring eclipse, visible from Earth’s Eastern Hemisphere.

Read more: Year’s closest new supermoon on August 30

Read more: What’s the youngest moon you can see?

Read more: 4 keys to understanding moon phases

Help EarthSky keep going! Please donate.

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Europe’s CHEOPS mission will shed light on strange new worlds

Artist’s concept of the just-launched CHEOPS space telescope, which will study hundreds of exoplanets in greater detail than ever before. Image via ESA/ ATG medialab/ DLR.

After a one-day delay, the European Space Agency (ESA) successfully launched its CHEOPS mission last week, on the morning of December 18, 2019, from the spaceport in Kourou, French Guiana. CHEOPS is the first ESA mission dedicated to studying exoplanets, those distant worlds orbiting other stars. NASA’s planet-hunting space missions, first Kepler and now TESS, have been finding new exoplanets. CHEOPS will study hundreds of exoplanets already known to exist – out of 4,000-plus now confirmed – to determine their sizes, masses, densities and possible atmospheres.

In this way, CHEOPS will take us some steps along the road of finding out what many exoworlds are actually like, not an easy task.

CHEOPS stands for CHaracterising ExOPlanets Satellite. The telescope will reside in a sun-synchronous orbit around Earth at an altitude of more than 400 miles (700 km). Kate Isaak, CHEOPS project scientist, said in a statement:

We are very excited to see the satellite blast off into space. There are so many interesting exoplanets and we will be following up on several hundreds of them, focusing in particular on the smaller planets in the size range between Earth and Neptune. They seem to be the commonly found planets in our Milky Way galaxy, yet we do not know much about them. CHEOPS will help us reveal the mysteries of these fascinating worlds, and take us one step closer to answering one of the most profound questions we humans ponder: are we alone in the universe?

Watch the launch below:

Heike Rauer, Director of the DLR Institute of Planetary Research in Berlin, said:

More than 4000 exoplanets have been discovered in the Milky Way, yet we still know far too little about these distant worlds in our cosmic neighborhood. We are all eager to see which ‘faces’ the planets characterized by CHEOPS will show us.

So how does CHEOPS observe these planets?

Like some other telescopes, it will watch as the planets transit in front of their stars, as seen from Earth. As Juan Cabrera Perez, Head of the Extrasolar Planets and Atmospheres Department at the DLR Institute of Planetary Research, explained:

We could describe this fluctuation in brightness as a ‘mini stellar eclipse’, as the transiting exoplanet reduces the intensity of the light from the star for a short time. This fluctuation can be measured and analyzed – an area in which we can contribute suitable tools and many years of experience.

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Cool photo of CHEOPS launch, December 18, 2019. Image via ESA/ S. Corvaja.

CHEOPS will focus on some of the most common exoplanets discovered so far, ranging in size from Earth to Neptune, or about approximately 6,000 to 30,000 miles (10,000 to 50,000 km) in diameter. Using data from the transits, CHEOPS can determine the size, mass and density of the planets. All of these are important in order for scientists to figure out the planets’ compositions. Some will be rocky like Earth, while others will have deep, gaseous atmospheres like Neptune or even Jupiter or Saturn. Knowing this will also help scientists determine which of these worlds might be potentially habitable. Of course, rocky planets similar in size to Earth, or a bit larger – super-Earths – would be the most interesting in this regard. Nicola Rando, CHEOPS project manager, said:

Both CHEOPS instrument and spacecraft are built to be extremely stable, so as to measure the incredibly small variations in the light of distant stars as their planets transit in front of them. For a planet like Earth, this amounts to the equivalent of watching the sun from a distant star and measuring its light dim by a tiny fraction of a percent. Now we are looking forward to the first part of the operational activities, making sure that the satellite and instrument perform as expected, ready for scientists to perform their world-class science.

CHEOPS will also be able to find out which of these planets do have atmospheres and whether they have clouds. This will help differentiate between deep, gaseous primordial atmospheres with no real solid surface between them, and thinner atmospheres like those on terrestrial planets such as Earth, Venus or Mars.

CHEOPS is just the first of three planned ESA missions to study exoplanets.

The Planetary Transits and Oscillations of stars (PLATO) space telescope, expected to launch in 2026, will focus on searching for “Earth-like” planets, ones that are rocky and about the same size as Earth orbiting in their stars’ habitable zones. So far, most such worlds have been found orbiting red dwarf stars, the most common type of star in our galaxy. CHEOPS, however, will look for these planets around sun-like stars. It will also be able to determine the age of these planetary systems with more accuracy than possible before.

A couple of years later, in 2028, ESA will launch the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, which will study the atmospheres of exoplanets. As well as atmospheric composition, this will help scientists develop a comprehensive catalog of exoplanetary orbits, radii, masses, densities and ages.

All three of these exciting missions, and others, will greatly increase our knowledge of these exotic, far-off worlds.

View larger. | Timeline of ESA and NASA exoplanet missions, including CHEOPS. Image via ESA.

As Günther Hasinger, ESA Director of Science, said:

CHEOPS will take exoplanet science to a whole new level. After the discovery of thousands of planets, the quest can now turn to characterization, investigating the physical and chemical properties of many exoplanets and really getting to know what they are made of and how they formed. CHEOPS will also pave the way for our future exoplanet missions, from the international James Webb Telescope to ESA’s very own PLATO and ARIEL satellites, keeping European science at the forefront of exoplanet research.

The CHEOPS mission is a partnership between ESA and Switzerland with additional contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the U.K. More than 100 scientists and engineers are involved. The nominal mission is expected to last 3 1/2 years. While the CHEOPS science team has the bulk of observation time, 20% of the time is reserved for other scientists from around the world.

CHEOPS and the coming follow-up missions will open an exciting new chapter in exoplanetary study. What fascinating discoveries will they make?

Bottom line: ESA has successfully launched its CHEOPS space telescope to study hundreds of exoplanets in more detail than ever before.

Via ESA

Via German Aerospace Center (DLR)

Read more: Visit CHEOPS website

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

Artist’s concept of the just-launched CHEOPS space telescope, which will study hundreds of exoplanets in greater detail than ever before. Image via ESA/ ATG medialab/ DLR.

After a one-day delay, the European Space Agency (ESA) successfully launched its CHEOPS mission last week, on the morning of December 18, 2019, from the spaceport in Kourou, French Guiana. CHEOPS is the first ESA mission dedicated to studying exoplanets, those distant worlds orbiting other stars. NASA’s planet-hunting space missions, first Kepler and now TESS, have been finding new exoplanets. CHEOPS will study hundreds of exoplanets already known to exist – out of 4,000-plus now confirmed – to determine their sizes, masses, densities and possible atmospheres.

In this way, CHEOPS will take us some steps along the road of finding out what many exoworlds are actually like, not an easy task.

CHEOPS stands for CHaracterising ExOPlanets Satellite. The telescope will reside in a sun-synchronous orbit around Earth at an altitude of more than 400 miles (700 km). Kate Isaak, CHEOPS project scientist, said in a statement:

We are very excited to see the satellite blast off into space. There are so many interesting exoplanets and we will be following up on several hundreds of them, focusing in particular on the smaller planets in the size range between Earth and Neptune. They seem to be the commonly found planets in our Milky Way galaxy, yet we do not know much about them. CHEOPS will help us reveal the mysteries of these fascinating worlds, and take us one step closer to answering one of the most profound questions we humans ponder: are we alone in the universe?

Watch the launch below:

Heike Rauer, Director of the DLR Institute of Planetary Research in Berlin, said:

More than 4000 exoplanets have been discovered in the Milky Way, yet we still know far too little about these distant worlds in our cosmic neighborhood. We are all eager to see which ‘faces’ the planets characterized by CHEOPS will show us.

So how does CHEOPS observe these planets?

Like some other telescopes, it will watch as the planets transit in front of their stars, as seen from Earth. As Juan Cabrera Perez, Head of the Extrasolar Planets and Atmospheres Department at the DLR Institute of Planetary Research, explained:

We could describe this fluctuation in brightness as a ‘mini stellar eclipse’, as the transiting exoplanet reduces the intensity of the light from the star for a short time. This fluctuation can be measured and analyzed – an area in which we can contribute suitable tools and many years of experience.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Cool photo of CHEOPS launch, December 18, 2019. Image via ESA/ S. Corvaja.

CHEOPS will focus on some of the most common exoplanets discovered so far, ranging in size from Earth to Neptune, or about approximately 6,000 to 30,000 miles (10,000 to 50,000 km) in diameter. Using data from the transits, CHEOPS can determine the size, mass and density of the planets. All of these are important in order for scientists to figure out the planets’ compositions. Some will be rocky like Earth, while others will have deep, gaseous atmospheres like Neptune or even Jupiter or Saturn. Knowing this will also help scientists determine which of these worlds might be potentially habitable. Of course, rocky planets similar in size to Earth, or a bit larger – super-Earths – would be the most interesting in this regard. Nicola Rando, CHEOPS project manager, said:

Both CHEOPS instrument and spacecraft are built to be extremely stable, so as to measure the incredibly small variations in the light of distant stars as their planets transit in front of them. For a planet like Earth, this amounts to the equivalent of watching the sun from a distant star and measuring its light dim by a tiny fraction of a percent. Now we are looking forward to the first part of the operational activities, making sure that the satellite and instrument perform as expected, ready for scientists to perform their world-class science.

CHEOPS will also be able to find out which of these planets do have atmospheres and whether they have clouds. This will help differentiate between deep, gaseous primordial atmospheres with no real solid surface between them, and thinner atmospheres like those on terrestrial planets such as Earth, Venus or Mars.

CHEOPS is just the first of three planned ESA missions to study exoplanets.

The Planetary Transits and Oscillations of stars (PLATO) space telescope, expected to launch in 2026, will focus on searching for “Earth-like” planets, ones that are rocky and about the same size as Earth orbiting in their stars’ habitable zones. So far, most such worlds have been found orbiting red dwarf stars, the most common type of star in our galaxy. CHEOPS, however, will look for these planets around sun-like stars. It will also be able to determine the age of these planetary systems with more accuracy than possible before.

A couple of years later, in 2028, ESA will launch the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, which will study the atmospheres of exoplanets. As well as atmospheric composition, this will help scientists develop a comprehensive catalog of exoplanetary orbits, radii, masses, densities and ages.

All three of these exciting missions, and others, will greatly increase our knowledge of these exotic, far-off worlds.

View larger. | Timeline of ESA and NASA exoplanet missions, including CHEOPS. Image via ESA.

As Günther Hasinger, ESA Director of Science, said:

CHEOPS will take exoplanet science to a whole new level. After the discovery of thousands of planets, the quest can now turn to characterization, investigating the physical and chemical properties of many exoplanets and really getting to know what they are made of and how they formed. CHEOPS will also pave the way for our future exoplanet missions, from the international James Webb Telescope to ESA’s very own PLATO and ARIEL satellites, keeping European science at the forefront of exoplanet research.

The CHEOPS mission is a partnership between ESA and Switzerland with additional contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the U.K. More than 100 scientists and engineers are involved. The nominal mission is expected to last 3 1/2 years. While the CHEOPS science team has the bulk of observation time, 20% of the time is reserved for other scientists from around the world.

CHEOPS and the coming follow-up missions will open an exciting new chapter in exoplanetary study. What fascinating discoveries will they make?

Bottom line: ESA has successfully launched its CHEOPS space telescope to study hundreds of exoplanets in more detail than ever before.

Via ESA

Via German Aerospace Center (DLR)

Read more: Visit CHEOPS website

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

Was the Christmas Star real?

Regulus and Leo I dwarf galaxy. Image via Russell Croman.

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

The Star of Bethlehem – nowadays often just called the Christmas Star – is a major seasonal symbol throughout the world.

Imagine, if you will, the silhouettes of three regally attired men on camels. They are gazing across gently rolling hills or dunes of white, to a tiny solitary building in the distance. The night is dark, and one exceedingly bright star appears to hover over the small building, sending a bright shaft of light earthward to illuminate its outline. Another light glows gently inside.

Basilica of Sant’Apollinare Nuovo in Ravenna, Italy: The Three Wise Men (named Balthasar, Melchior, and Gaspar). Detail from 6th-century Mary and Child surrounded by angels mosaic, by the so-called “Master of Sant’Apollinare”. Image via Wikipedia.

That is the picture most of us have of the Christmas Star, but it’s an image derived more from imagination and greeting cards than from the Bible. In fact, the Gospel of Matthew in the New Testament is the only place this “star” is mentioned in the Bible (Matt 2:2, 7-10, King James Version). Even there, information on the star is sparse. The most telling reference is Matt. 2:9:

When they had heard the king, they departed; and, lo, the star, which they saw in the east, went before them, till it came and stood over where the young child was.

For anyone inclined to insist on the literal truth of scripture, this verse solves the question. If this verse is literally true, then the Star of Bethlehem could not have been any known natural phenomenon, simply because none would move that way.

However, if we grant the author of Matthew – who assuredly was not an eyewitness at the Nativity – a little artistic license, the “star” might not have appeared literally in the way described. In that case we can consider some natural, astronomical possibilities. In fact, there is some uncertainty about the use of the word for star in the Greek manuscript. Some contend that the word could have meant or implied an object other than a physical star.

Aaron Robinson caught this Geminid meteor on December 14, 2018, in Ririe, Idaho.

Some artistic depictions show what appear to be a bright meteor or “falling star.” Although exploding meteors, sometimes called bolides or fireballs, can be startling and truly impressive, they last only seconds. They can occur at any time. People far more aware of the night sky than the modern city dweller is likely would not have placed much significance in them. Such transient phenomena could not possibly have “led” the wise men (the Bible never calls them “kings”) to Bethlehem.

There are other astronomical objects or events that might have seemed more significant, but there are problems. First off, we don’t know for sure when Jesus was born. Due to an error by a Church cleric hundreds of years later, the birth of Jesus was thought to be at least four years later than it really was. So today we know that the birth was no later than 4 B.C., and it could have been a little earlier. And it certainly was not on December 25. The Bible does not say, leaving us few clues. One clue we do have, however, is the reference that shepherds were out in the field “keeping watch over their flock by night” (Luke 2:8), something the scholars say was likely only done in the spring when lambs were born. Thus the birth was likely in the spring, probably between 7 and 4 B.C.

Few astronomical records were kept at the time, except by the Chinese and Koreans. They did record what might have been comets in 5 and possibly again in 4 B.C. The main problem here is that comets were generally regarded as omens of evil and bad fortune by the Chinese and likely also by the magi-astrologers the New Testament calls “wise men.” Rather than follow such a cometary “star,” they likely would have gone the other way.

Another possibility is that the Christmas Star was a nova or supernova, a previously unseen star that suddenly brightens in a big way. Indeed, one such star was recorded by the Chinese in the spring of 5 B.C, and was seen for more than two months. However, its position in the constellation Capricornus meant that it likely would not have seemed to “lead” the wise men in the manner implied in the Bible.

For some, the star was not really a star at all, but a planet, Jupiter. Or more precisely, it was the conjunction or close meeting of Jupiter with two other planets, Saturn and Mars. Planets were “wandering stars” to the ancients, and to many they bore great astrological or mystical significance. Astronomers know that there was a series of such conjunctions in 6 and 5 B.C., occurring in the constellation Pisces (the Fishes), said by some to be the astrological “sign of the Jews.” To add more credence for later Christian writers such as Matthew, the sign of a fish later became the secret sign for Christians.

Mosaic pavement of a 6th century synagogue at Beth Alpha, Jezreel Valley, northern Israel. It was discovered in 1928. Signs of the zodiac surround the central chariot of the sun (a Greek motif), while the corners depict the 4 “turning points” (“tekufot”) of the year, solstices and equinoxes, each named for the month in which it occurs- tequfah of Tishrei, (tequfah of Tevet), tequfah of Ni(san), tequfah of Tamuz. Image via Wikipedia.

Unless some major and indisputable archaeological discovery is found to settle the question once and for all, the mystery of what the Christmas Star was will remain in the realm of faith. Science cannot explain it as any known physical object; history offers no clear record; and religion offers only an untestable miraculous apparition. But although there may be no agreement on the nature of the star or even its actual sighting two millenia ago, all sides can agree on the message the Christmas star heralded: “… on earth peace, good will toward men.” (Luke 2:14).

Bottom line: Some possible astronomical explanations for the Star of Bethlehem or Christmas star.

from EarthSky https://ift.tt/2T3SaWb

Regulus and Leo I dwarf galaxy. Image via Russell Croman.

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

The Star of Bethlehem – nowadays often just called the Christmas Star – is a major seasonal symbol throughout the world.

Imagine, if you will, the silhouettes of three regally attired men on camels. They are gazing across gently rolling hills or dunes of white, to a tiny solitary building in the distance. The night is dark, and one exceedingly bright star appears to hover over the small building, sending a bright shaft of light earthward to illuminate its outline. Another light glows gently inside.

Basilica of Sant’Apollinare Nuovo in Ravenna, Italy: The Three Wise Men (named Balthasar, Melchior, and Gaspar). Detail from 6th-century Mary and Child surrounded by angels mosaic, by the so-called “Master of Sant’Apollinare”. Image via Wikipedia.

That is the picture most of us have of the Christmas Star, but it’s an image derived more from imagination and greeting cards than from the Bible. In fact, the Gospel of Matthew in the New Testament is the only place this “star” is mentioned in the Bible (Matt 2:2, 7-10, King James Version). Even there, information on the star is sparse. The most telling reference is Matt. 2:9:

When they had heard the king, they departed; and, lo, the star, which they saw in the east, went before them, till it came and stood over where the young child was.

For anyone inclined to insist on the literal truth of scripture, this verse solves the question. If this verse is literally true, then the Star of Bethlehem could not have been any known natural phenomenon, simply because none would move that way.

However, if we grant the author of Matthew – who assuredly was not an eyewitness at the Nativity – a little artistic license, the “star” might not have appeared literally in the way described. In that case we can consider some natural, astronomical possibilities. In fact, there is some uncertainty about the use of the word for star in the Greek manuscript. Some contend that the word could have meant or implied an object other than a physical star.

Aaron Robinson caught this Geminid meteor on December 14, 2018, in Ririe, Idaho.

Some artistic depictions show what appear to be a bright meteor or “falling star.” Although exploding meteors, sometimes called bolides or fireballs, can be startling and truly impressive, they last only seconds. They can occur at any time. People far more aware of the night sky than the modern city dweller is likely would not have placed much significance in them. Such transient phenomena could not possibly have “led” the wise men (the Bible never calls them “kings”) to Bethlehem.

There are other astronomical objects or events that might have seemed more significant, but there are problems. First off, we don’t know for sure when Jesus was born. Due to an error by a Church cleric hundreds of years later, the birth of Jesus was thought to be at least four years later than it really was. So today we know that the birth was no later than 4 B.C., and it could have been a little earlier. And it certainly was not on December 25. The Bible does not say, leaving us few clues. One clue we do have, however, is the reference that shepherds were out in the field “keeping watch over their flock by night” (Luke 2:8), something the scholars say was likely only done in the spring when lambs were born. Thus the birth was likely in the spring, probably between 7 and 4 B.C.

Few astronomical records were kept at the time, except by the Chinese and Koreans. They did record what might have been comets in 5 and possibly again in 4 B.C. The main problem here is that comets were generally regarded as omens of evil and bad fortune by the Chinese and likely also by the magi-astrologers the New Testament calls “wise men.” Rather than follow such a cometary “star,” they likely would have gone the other way.

Another possibility is that the Christmas Star was a nova or supernova, a previously unseen star that suddenly brightens in a big way. Indeed, one such star was recorded by the Chinese in the spring of 5 B.C, and was seen for more than two months. However, its position in the constellation Capricornus meant that it likely would not have seemed to “lead” the wise men in the manner implied in the Bible.

For some, the star was not really a star at all, but a planet, Jupiter. Or more precisely, it was the conjunction or close meeting of Jupiter with two other planets, Saturn and Mars. Planets were “wandering stars” to the ancients, and to many they bore great astrological or mystical significance. Astronomers know that there was a series of such conjunctions in 6 and 5 B.C., occurring in the constellation Pisces (the Fishes), said by some to be the astrological “sign of the Jews.” To add more credence for later Christian writers such as Matthew, the sign of a fish later became the secret sign for Christians.

Mosaic pavement of a 6th century synagogue at Beth Alpha, Jezreel Valley, northern Israel. It was discovered in 1928. Signs of the zodiac surround the central chariot of the sun (a Greek motif), while the corners depict the 4 “turning points” (“tekufot”) of the year, solstices and equinoxes, each named for the month in which it occurs- tequfah of Tishrei, (tequfah of Tevet), tequfah of Ni(san), tequfah of Tamuz. Image via Wikipedia.

Unless some major and indisputable archaeological discovery is found to settle the question once and for all, the mystery of what the Christmas Star was will remain in the realm of faith. Science cannot explain it as any known physical object; history offers no clear record; and religion offers only an untestable miraculous apparition. But although there may be no agreement on the nature of the star or even its actual sighting two millenia ago, all sides can agree on the message the Christmas star heralded: “… on earth peace, good will toward men.” (Luke 2:14).

Bottom line: Some possible astronomical explanations for the Star of Bethlehem or Christmas star.

from EarthSky https://ift.tt/2T3SaWb

Solstice sun at southernmost point

Image above: “First light of winter,” wrote Karl Diefenderfer in Yardley, Pennsylvania.

You might think of the solstice as a day, but it’s really a moment. The December solstice happens at 4:19 UTC on December 22, 2019. That time – the moment of solstice – marks the sun’s southernmost point in our sky for this year.

Here in North America, the solstice happens on December 21 (11:19 p.m. EST, 10:19 p.m. CST, 9:19 p.m. MST, 8:19 p.m. PST, 7:19 p.m. Alaskan Time and 6:19 p.m. Hawaiian Time). When is the moment of solstice for your location? Translate December 22 at 4:19 UTC to your time zone, here.

Looking at the world map below, you can see that the 2019 December solstice happens when it’s sunset (December 21) in the Pacific Ocean, midnight (December 21-22) in South America, sunrise (December 22) in Africa and the Middle East, and noontime (December 22) for East Asia.

By noontime, we mean midday, or midway between sunrise and sunset. By midnight, we mean the middle of the night, or midway between sunset and sunrise.

Day and night sides of Earth at the instant of the December 2019 solstice (December 22, 2019, at 4:19 UTC). Image via EarthView.

On the December solstice, we celebrate the unofficial first day of winter in the Northern Hemisphere and first day of summer in the Southern Hemisphere. Unofficial? Yes. Winter and summer start at the solstices by tradition, not official decree.

Yet these solstices bring very real occurrences to our sky, which you can witness for yourself. In both the Northern and Southern Hemispheres, the December solstice brings the southernmost sunrise and the southernmost sunset of the year. If you stand in one spot day after day, week after week – for example, gazing out a particular window toward the sunrise or sunset on the horizon – you will surely notice the sunset’s northward trek along the horizon over the coming months.

From time to time, try fixing a bit of tape to your window, on which you’ve written the date, to help you mark the sun’s passage. Or notice it with respect to landmarks in your surroundings, as Peter Lowenstein did, below:

Solstice sunsets, showing the sun’s position on the local horizon at December (left) and June (right) solstices from Mutare, Zimbabwe, via Peter Lowenstein.

In the Northern Hemisphere, the southernmost sunrise and sunset usher in the year’s shortest day and the longest night.

In the Southern Hemisphere, it’s the exact opposite, where the year’s southernmost sunrise and sunset give the Southern Hemisphere its longest day and shortest night.

Not every place worldwide has a sunrise and a sunset on the day of the December solstice. North of the Arctic Circle – or north of 66.5 degrees north latitude – there is no sunrise or sunset today, because the sun stays beneath the horizon all day long. South of the Antarctic Circle – at 66.5 degrees south of the equator – you won’t see a sunrise or sunset either, because the sun stays above the horizon all day.

After the sun reaches its southernmost point on the sky’s dome on the December solstice, watch as the sun seems to pause for a number of days before it starts its northward trajectory on the sky’s dome once again.

Earth has seasons because our world is tilted on its axis with respect to our orbit around the sun. Image via NASA.

Bottom line: In 2019, the December solstice comes on December 21 at 10:19 p.m. CST. That’s December 22 at 4:19 UTC. It’s when the sun on our sky’s dome reaches its farthest southward point for the year. Happy solstice, everyone!

Want more? Click here to read more about the December solstice

A solstice tale of two cities

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

from EarthSky https://ift.tt/2ZbshI9

Image above: “First light of winter,” wrote Karl Diefenderfer in Yardley, Pennsylvania.

You might think of the solstice as a day, but it’s really a moment. The December solstice happens at 4:19 UTC on December 22, 2019. That time – the moment of solstice – marks the sun’s southernmost point in our sky for this year.

Here in North America, the solstice happens on December 21 (11:19 p.m. EST, 10:19 p.m. CST, 9:19 p.m. MST, 8:19 p.m. PST, 7:19 p.m. Alaskan Time and 6:19 p.m. Hawaiian Time). When is the moment of solstice for your location? Translate December 22 at 4:19 UTC to your time zone, here.

Looking at the world map below, you can see that the 2019 December solstice happens when it’s sunset (December 21) in the Pacific Ocean, midnight (December 21-22) in South America, sunrise (December 22) in Africa and the Middle East, and noontime (December 22) for East Asia.

By noontime, we mean midday, or midway between sunrise and sunset. By midnight, we mean the middle of the night, or midway between sunset and sunrise.

Day and night sides of Earth at the instant of the December 2019 solstice (December 22, 2019, at 4:19 UTC). Image via EarthView.

On the December solstice, we celebrate the unofficial first day of winter in the Northern Hemisphere and first day of summer in the Southern Hemisphere. Unofficial? Yes. Winter and summer start at the solstices by tradition, not official decree.

Yet these solstices bring very real occurrences to our sky, which you can witness for yourself. In both the Northern and Southern Hemispheres, the December solstice brings the southernmost sunrise and the southernmost sunset of the year. If you stand in one spot day after day, week after week – for example, gazing out a particular window toward the sunrise or sunset on the horizon – you will surely notice the sunset’s northward trek along the horizon over the coming months.

From time to time, try fixing a bit of tape to your window, on which you’ve written the date, to help you mark the sun’s passage. Or notice it with respect to landmarks in your surroundings, as Peter Lowenstein did, below:

Solstice sunsets, showing the sun’s position on the local horizon at December (left) and June (right) solstices from Mutare, Zimbabwe, via Peter Lowenstein.

In the Northern Hemisphere, the southernmost sunrise and sunset usher in the year’s shortest day and the longest night.

In the Southern Hemisphere, it’s the exact opposite, where the year’s southernmost sunrise and sunset give the Southern Hemisphere its longest day and shortest night.

Not every place worldwide has a sunrise and a sunset on the day of the December solstice. North of the Arctic Circle – or north of 66.5 degrees north latitude – there is no sunrise or sunset today, because the sun stays beneath the horizon all day long. South of the Antarctic Circle – at 66.5 degrees south of the equator – you won’t see a sunrise or sunset either, because the sun stays above the horizon all day.

After the sun reaches its southernmost point on the sky’s dome on the December solstice, watch as the sun seems to pause for a number of days before it starts its northward trajectory on the sky’s dome once again.

Earth has seasons because our world is tilted on its axis with respect to our orbit around the sun. Image via NASA.

Bottom line: In 2019, the December solstice comes on December 21 at 10:19 p.m. CST. That’s December 22 at 4:19 UTC. It’s when the sun on our sky’s dome reaches its farthest southward point for the year. Happy solstice, everyone!

Want more? Click here to read more about the December solstice

A solstice tale of two cities

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

from EarthSky https://ift.tt/2ZbshI9

News digest – prostate cancer MRI trial, drug delivery, cancer ‘cures’ on Facebook and weight loss

A prostate cancer MRI trial is in progress

BBC News reports on a new large-scale trial that will test if MRI scans could be used to screen men for prostate cancer. The trial will invite 300 randomly selected men aged 50 to 75 years old to have a 10-minute MRI scan and a PSA blood test. Scientists are hoping to find out if using MRI in this way could help to flag men who have signs of prostate cancer without the need for a biopsy. We’ve blogged before about how scientists are working to improve prostate cancer diagnosis.

Treatment that delivers drug straight to tumour given for the first time

A British woman is the first person in the world to receive a new treatment that aims to deliver high doses of chemotherapy directly to cancer cells. The treatment, which uses tiny clusters of bubbles and liquid droplets to enhance the delivery of chemotherapy, is part of a clinical trial being carried out in London that’s looking to reduce the number of doses of chemotherapy and its side effects for cancer patients. Read the full story in The Metro.

WHO approves cheap copy of common breast cancer drug

A cheaper version of the breast cancer drug Herceptin has been approved by the World Health Organisation (WHO). This decision will make it possible for women in low-income countries to benefit from treatment. This type of hormone therapy blocks off certain cancers’ fuel supply. More on this in The Guardian.

Facebook bans ads promoting fake cancer ‘cures’

Several Facebook groups promoting a dangerous skin cancer ‘treatment’ have been banned from the social media channel, following concerns about ‘sensational health claims’. Groups were promoting a black salve paste, which they claimed had the ability to cure skin cancer by ‘eating away’ at only cancerous cells. According to Buzzfeed News, the groups have been found to be in violation of Facebook rules that prohibit ‘violent and criminal behaviour’. Commenting on the story, experts strongly advised anyone considering taking an alternative or complimentary medicine to seek advice from a trained medical professional.

And finally

The Mail Online covers a study that says that post-menopausal women who are overweight could reduce their risk of breast cancer if they lose at least 20lbs. But the results present quite a complicated picture. Women who had sustained weight loss only had a reduced cancer risk if they weren’t taking hormone replacement therapy (HRT). And because hormone replacement therapy can increase the risk of breast cancer too, it’s hard to untangle which risk factor is having an effect. Unfortunately, there’s still not enough evidence to know what effect different patterns of weight loss can have on cancer risk.

Scarlett Sangster is a writer for PA Media Group 

from Cancer Research UK – Science blog https://ift.tt/2s8j6fw

A prostate cancer MRI trial is in progress

BBC News reports on a new large-scale trial that will test if MRI scans could be used to screen men for prostate cancer. The trial will invite 300 randomly selected men aged 50 to 75 years old to have a 10-minute MRI scan and a PSA blood test. Scientists are hoping to find out if using MRI in this way could help to flag men who have signs of prostate cancer without the need for a biopsy. We’ve blogged before about how scientists are working to improve prostate cancer diagnosis.

Treatment that delivers drug straight to tumour given for the first time

A British woman is the first person in the world to receive a new treatment that aims to deliver high doses of chemotherapy directly to cancer cells. The treatment, which uses tiny clusters of bubbles and liquid droplets to enhance the delivery of chemotherapy, is part of a clinical trial being carried out in London that’s looking to reduce the number of doses of chemotherapy and its side effects for cancer patients. Read the full story in The Metro.

WHO approves cheap copy of common breast cancer drug

A cheaper version of the breast cancer drug Herceptin has been approved by the World Health Organisation (WHO). This decision will make it possible for women in low-income countries to benefit from treatment. This type of hormone therapy blocks off certain cancers’ fuel supply. More on this in The Guardian.

Facebook bans ads promoting fake cancer ‘cures’

Several Facebook groups promoting a dangerous skin cancer ‘treatment’ have been banned from the social media channel, following concerns about ‘sensational health claims’. Groups were promoting a black salve paste, which they claimed had the ability to cure skin cancer by ‘eating away’ at only cancerous cells. According to Buzzfeed News, the groups have been found to be in violation of Facebook rules that prohibit ‘violent and criminal behaviour’. Commenting on the story, experts strongly advised anyone considering taking an alternative or complimentary medicine to seek advice from a trained medical professional.

And finally

The Mail Online covers a study that says that post-menopausal women who are overweight could reduce their risk of breast cancer if they lose at least 20lbs. But the results present quite a complicated picture. Women who had sustained weight loss only had a reduced cancer risk if they weren’t taking hormone replacement therapy (HRT). And because hormone replacement therapy can increase the risk of breast cancer too, it’s hard to untangle which risk factor is having an effect. Unfortunately, there’s still not enough evidence to know what effect different patterns of weight loss can have on cancer risk.

Scarlett Sangster is a writer for PA Media Group 

from Cancer Research UK – Science blog https://ift.tt/2s8j6fw