Asteroid to sweep close October 11-12

In this flyby simulation, Earth is the blue dot. A geosynchronous satellite and its orbit are purple. The moon’s orbit is white. The asteroid’s path sweeps by on a green path. Watch how the orbit of 2012 TC4 gets deflected as it passes by Earth, turning darker as it dips below the ecliptic plane. Image Created with orbitsimulator.com, via Tony873004/AstroBob.

The Center for Near Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California – and other astronomers and observatories around the globe – have had their eye on a small asteroid, designated 2012 TC4. It’ll pass close to Earth on October 11-12, 2017. Last summer, experts were already saying they knew the rock wouldn’t hit us, but they thought 2012 TC4 might give us a close shave, passing as close as 4,200 miles (6,800 km). In late July, though, astronomers recovered the space rock – picked it up telescopically again, after not seeing it for some years – and the new observations let them refine their knowledge of 2012 TC4’s orbit and better compute its closest distance to Earth later this month. Thus we now know the object will pass around 30,000 miles (50,000 km) above Earth’s surface.

This animation depicts the safe flyby of asteroid 2012 TC4 as it passes under Earth on October 11-12, 2017. It’ll pass fewer than 9,000 miles from the belt of communications satellites that ring the Earth in geosynchronous orbits, which are about 26,000 miles (40,000 km) above Earth. Image via NASA/ JPL-Caltech/ UANews.

2012 TC4 will come closest to Earth around 05:42 UTC on October 12 (12:42 a.m. CDT; translate to your time zone). It’ll come close enough that Earth’s gravity will slightly alter the asteroid’s path. Later in the day on October 12 – at 19:19 UTC (2:19 p.m. Central), the asteroid will pass some 172,000 miles (277,000 km) from the moon.

The asteroid is currently travelling at a speed of about 30,000 mph (nearly 50,000 kph) and while it appears very dim at the moment, it’ll get brighter as it gets closer.

Can you see asteroid 2012 TC4 as it sweeps past? Not with the eye alone, surely. But experienced observers with telescopes and charting software will be able to pick it up, and you can watch online as the asteroid passes. The Virtual Telescope Project in Italy will offer two online observing sessions, on October 11 and 12, in cooperation with Tenagra Observatories in Arizona. Click here to go to Virtual Telescope’s observing page for 2012 TC4.

Image of asteroid 2012 TC4 from 2012, via G. Masi and F. Nocentini/ Virtual Telescope Project.

Experienced backyard observers have a shot at the asteroid, too. To see it, you’ll need to make your own tracking map using sky charting software. AstroBob has instructions on how to do that at his blog. He wrote:

Observers in the Americas (especially South America) will get the best views as 2012 TC4 hurtles from Capricornus across Microscopium and into southern Sagittarius during early evening hours. [The locator map below], with stars to magnitude 8, shows the asteroid’s trajectory across the evening sky on the evening of October 11. Positions are shown every hour starting at 8:30 p.m. CDT. 2012 TC4 will be much fainter, around magnitude 13.

Find instructions for how to create your tracking map near the end of AstroBob’s October 3 blog post on 2012 TC4.

Chart showing the path across our sky of asteroid 2012 TC4, created with Chris Marriott’s SkyMap, via AstroBob.

Meanwhile, CNEOS is working with astronomers of the International Asteroid Warning Network on a plan to utilize asteroid 2012 TC4 in an exercise to test NASA’s network for planetary defense against asteroids. They’ve said they intend to test out their ability to recover, characterize and report on a potentially hazardous object approaching Earth.

Recover, in this sense, doesn’t mean recovering a sample from an asteroid; it means recovering the object via telescopes as it moves across the heavens, using tracking data from an earlier pass. The calculations on the October, 2017 pass of asteroid 2012 TC4, for example, were originally based on only seven days of tracking it, shortly after it was discovered in 2012. Then we lost the object again, in the depths of space, as it sped away from us. That’s an exceedingly common scenario for close-passing asteroids, which are, after all, just flying chunks (some more like flying mountains) of rock in space. They sweep past, then go their way.

These astronomers are trying out their planetary defense systems – a global protection against asteroids on a possible collision course with Earth – which they’ve been discussing for decades and developing over the last few years.

Vishnu Reddy of the UA Lunar Planetary Laboratory. “The question is: How prepared are we for the next cosmic threat?” Image via Bob Demers/ UANews.

Brightness measurements made during the week it was observed in 2012 gave an estimated size of 30 to 100 feet (10 to 30 meters) for asteroid 2012 TC4. That’s comparable to the meteor that caused a shock wave and explosion in Earth’s atmosphere, over the Russian city of Chelyabinsk, in February 2013, injuring 1,500 people and damaging over 7,000 buildings. The Chelyabinsk meteor, before it struck Earth’s atmosphere, is estimated to have been about 20 meters wide.

Astronomers also know that 2012 TC4 is an elongated and rapidly rotating asteroid.

And they know that asteroid 2012 TC4 has made many close approaches to Earth in the past.

Illustration of a possible orbit for asteroid 2012 TC4, via NASA.

Bottom line: A small asteroid designated 2012 TC4 will pass Earth safely – but closely – on October 12, 2017. Experts are certain it won’t hit Earth. This summer, an international collaboration of telescopes is trying to reacquire the asteroid – that is, find it again in space – with the goal of precisely determining its orbit.

Via CNEOS and UANews.

from EarthSky http://ift.tt/2uJVddV

In this flyby simulation, Earth is the blue dot. A geosynchronous satellite and its orbit are purple. The moon’s orbit is white. The asteroid’s path sweeps by on a green path. Watch how the orbit of 2012 TC4 gets deflected as it passes by Earth, turning darker as it dips below the ecliptic plane. Image Created with orbitsimulator.com, via Tony873004/AstroBob.

The Center for Near Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California – and other astronomers and observatories around the globe – have had their eye on a small asteroid, designated 2012 TC4. It’ll pass close to Earth on October 11-12, 2017. Last summer, experts were already saying they knew the rock wouldn’t hit us, but they thought 2012 TC4 might give us a close shave, passing as close as 4,200 miles (6,800 km). In late July, though, astronomers recovered the space rock – picked it up telescopically again, after not seeing it for some years – and the new observations let them refine their knowledge of 2012 TC4’s orbit and better compute its closest distance to Earth later this month. Thus we now know the object will pass around 30,000 miles (50,000 km) above Earth’s surface.

This animation depicts the safe flyby of asteroid 2012 TC4 as it passes under Earth on October 11-12, 2017. It’ll pass fewer than 9,000 miles from the belt of communications satellites that ring the Earth in geosynchronous orbits, which are about 26,000 miles (40,000 km) above Earth. Image via NASA/ JPL-Caltech/ UANews.

2012 TC4 will come closest to Earth around 05:42 UTC on October 12 (12:42 a.m. CDT; translate to your time zone). It’ll come close enough that Earth’s gravity will slightly alter the asteroid’s path. Later in the day on October 12 – at 19:19 UTC (2:19 p.m. Central), the asteroid will pass some 172,000 miles (277,000 km) from the moon.

The asteroid is currently travelling at a speed of about 30,000 mph (nearly 50,000 kph) and while it appears very dim at the moment, it’ll get brighter as it gets closer.

Can you see asteroid 2012 TC4 as it sweeps past? Not with the eye alone, surely. But experienced observers with telescopes and charting software will be able to pick it up, and you can watch online as the asteroid passes. The Virtual Telescope Project in Italy will offer two online observing sessions, on October 11 and 12, in cooperation with Tenagra Observatories in Arizona. Click here to go to Virtual Telescope’s observing page for 2012 TC4.

Image of asteroid 2012 TC4 from 2012, via G. Masi and F. Nocentini/ Virtual Telescope Project.

Experienced backyard observers have a shot at the asteroid, too. To see it, you’ll need to make your own tracking map using sky charting software. AstroBob has instructions on how to do that at his blog. He wrote:

Observers in the Americas (especially South America) will get the best views as 2012 TC4 hurtles from Capricornus across Microscopium and into southern Sagittarius during early evening hours. [The locator map below], with stars to magnitude 8, shows the asteroid’s trajectory across the evening sky on the evening of October 11. Positions are shown every hour starting at 8:30 p.m. CDT. 2012 TC4 will be much fainter, around magnitude 13.

Find instructions for how to create your tracking map near the end of AstroBob’s October 3 blog post on 2012 TC4.

Chart showing the path across our sky of asteroid 2012 TC4, created with Chris Marriott’s SkyMap, via AstroBob.

Meanwhile, CNEOS is working with astronomers of the International Asteroid Warning Network on a plan to utilize asteroid 2012 TC4 in an exercise to test NASA’s network for planetary defense against asteroids. They’ve said they intend to test out their ability to recover, characterize and report on a potentially hazardous object approaching Earth.

Recover, in this sense, doesn’t mean recovering a sample from an asteroid; it means recovering the object via telescopes as it moves across the heavens, using tracking data from an earlier pass. The calculations on the October, 2017 pass of asteroid 2012 TC4, for example, were originally based on only seven days of tracking it, shortly after it was discovered in 2012. Then we lost the object again, in the depths of space, as it sped away from us. That’s an exceedingly common scenario for close-passing asteroids, which are, after all, just flying chunks (some more like flying mountains) of rock in space. They sweep past, then go their way.

These astronomers are trying out their planetary defense systems – a global protection against asteroids on a possible collision course with Earth – which they’ve been discussing for decades and developing over the last few years.

Vishnu Reddy of the UA Lunar Planetary Laboratory. “The question is: How prepared are we for the next cosmic threat?” Image via Bob Demers/ UANews.

Brightness measurements made during the week it was observed in 2012 gave an estimated size of 30 to 100 feet (10 to 30 meters) for asteroid 2012 TC4. That’s comparable to the meteor that caused a shock wave and explosion in Earth’s atmosphere, over the Russian city of Chelyabinsk, in February 2013, injuring 1,500 people and damaging over 7,000 buildings. The Chelyabinsk meteor, before it struck Earth’s atmosphere, is estimated to have been about 20 meters wide.

Astronomers also know that 2012 TC4 is an elongated and rapidly rotating asteroid.

And they know that asteroid 2012 TC4 has made many close approaches to Earth in the past.

Illustration of a possible orbit for asteroid 2012 TC4, via NASA.

Bottom line: A small asteroid designated 2012 TC4 will pass Earth safely – but closely – on October 12, 2017. Experts are certain it won’t hit Earth. This summer, an international collaboration of telescopes is trying to reacquire the asteroid – that is, find it again in space – with the goal of precisely determining its orbit.

Via CNEOS and UANews.

from EarthSky http://ift.tt/2uJVddV

2017 Nobel Prize in Chemistry: how making microscopes cool is helping cancer research

As a research charity, cool science always gets us excited. But the tech that yesterday earned its pioneers this year’s Nobel Prize in Chemistry is so cool it’s sub-zero: cryo-electron microscopy.

Far from the microscopes we used in school to examine strands of our hair and the features of onion skins, this form of imaging has allowed researchers to picture the molecules of life in detail previously inconceivable.

Central to the technique’s prying is getting its subjects cold. Very cold. And these frigid microscopes are helping researchers make real progress in cancer science.

It works by bombarding samples with a powerful beam of electrons – tiny particles that spin around the hearts of atoms. The beam is so strong that it was believed this technique, called electron microscopy, could only be used on dead or non-living things because of the damage it caused to biological molecules. This, on the whole, isn’t ideal when the goal is to get a picture of the molecules of life itself.

This is where one of the Nobel laureates, Dr Richard Henderson from the MRC Laboratory of Molecular Biology, Cambridge, comes in. He was the first to use electron microscopy (EM) to capture a 3D image of a protein, the molecules that our DNA contains the recipes for.

“I am delighted for everybody in the field that the Nobel Prize for Chemistry has been awarded to acknowledge the success of cryo-EM,” he says in a statement about the award.

But Henderson wouldn’t have made that crucial advance without the other two laureates. Over the course of almost a decade, Professor Joachim Frank, from Columbia University in the US, worked out how to merge 2D images into crisp 3D versions. Also working in the 1980s, Professor Jacques Dubochet, from the University of Lausanne in Switzerland, found that rapidly cooling the samples in water allowed them to maintain their shape.

Together, this trio has opened our eyes to a microscopic realm that’s helping scientists better understand the molecular workings of the world of biology – from bacteria to cancer cells. We spoke to two experts using the technique to study cancer to find out why it’s so exciting.

The devil isn’t in the detail

The ability of cryo-EM to essentially freeze biological molecules in time is helping researchers understand what’s going right, and wrong, inside cancer cells.

“Cryo-EM is exciting because it allows us to study the structure of biological molecules that we previously weren’t able to, in incredible detail,” says Professor Richard Bayliss, a Cancer Research UK-funded structural biology expert from the University of Leeds.

“This helps us understand how they work, but also to study those that are faulty in cancer. By giving us insight into what’s happening at the molecular level, we can develop ideas on how we can design drugs to precisely block these faulty molecules – that’ll be a major achievement.”

Before cryo-EM came on the scene, achieving such a level of detail was tricky.

“Previously, the field of structural biology has been driven primarily by one microscopy technique: x-ray crystallography,” says Professor Laurence Pearl, a Cancer Research UK-funded structural biologist from the University of Sussex.

“It’s very powerful, but it’s a challenging and unpredictable technique. It’s also limited in its ability to study fully assembled ‘biological machines’ as they work in the cell. It’s like being able to study just the engine of a car, but not how this integrates with the rest of the parts.”

This is where cryo-EM comes in.

“Now we have the ability to look at the big biological machines in the state that they operate in cells and understand how they function, and how that function is altered by genetic faults in cancer,” Pearl says.

“This understanding of structure and function speeds up our ability to discover and design new cancer drugs.”

For now, the hefty multi-million pound price tag of state-of-the art machines capable of capturing the highest levels of molecular detail means they aren’t too widely available to scientists. And this limited access has meant that the capabilities of cryo-EM have yet to be fully realised. But that’s something that Bayliss sees as an opportunity.

“Once more people have their hands on this technology, we’ll find a lot more applications for it,” he says.

“It’s allowing us to be more ambitious about the kind of work we can do and start projects we couldn’t have thought of before. It’s exciting to see what’s happening.”

Justine 

from Cancer Research UK – Science blog http://ift.tt/2xjK7ZM

As a research charity, cool science always gets us excited. But the tech that yesterday earned its pioneers this year’s Nobel Prize in Chemistry is so cool it’s sub-zero: cryo-electron microscopy.

Far from the microscopes we used in school to examine strands of our hair and the features of onion skins, this form of imaging has allowed researchers to picture the molecules of life in detail previously inconceivable.

Central to the technique’s prying is getting its subjects cold. Very cold. And these frigid microscopes are helping researchers make real progress in cancer science.

It works by bombarding samples with a powerful beam of electrons – tiny particles that spin around the hearts of atoms. The beam is so strong that it was believed this technique, called electron microscopy, could only be used on dead or non-living things because of the damage it caused to biological molecules. This, on the whole, isn’t ideal when the goal is to get a picture of the molecules of life itself.

This is where one of the Nobel laureates, Dr Richard Henderson from the MRC Laboratory of Molecular Biology, Cambridge, comes in. He was the first to use electron microscopy (EM) to capture a 3D image of a protein, the molecules that our DNA contains the recipes for.

“I am delighted for everybody in the field that the Nobel Prize for Chemistry has been awarded to acknowledge the success of cryo-EM,” he says in a statement about the award.

But Henderson wouldn’t have made that crucial advance without the other two laureates. Over the course of almost a decade, Professor Joachim Frank, from Columbia University in the US, worked out how to merge 2D images into crisp 3D versions. Also working in the 1980s, Professor Jacques Dubochet, from the University of Lausanne in Switzerland, found that rapidly cooling the samples in water allowed them to maintain their shape.

Together, this trio has opened our eyes to a microscopic realm that’s helping scientists better understand the molecular workings of the world of biology – from bacteria to cancer cells. We spoke to two experts using the technique to study cancer to find out why it’s so exciting.

The devil isn’t in the detail

The ability of cryo-EM to essentially freeze biological molecules in time is helping researchers understand what’s going right, and wrong, inside cancer cells.

“Cryo-EM is exciting because it allows us to study the structure of biological molecules that we previously weren’t able to, in incredible detail,” says Professor Richard Bayliss, a Cancer Research UK-funded structural biology expert from the University of Leeds.

“This helps us understand how they work, but also to study those that are faulty in cancer. By giving us insight into what’s happening at the molecular level, we can develop ideas on how we can design drugs to precisely block these faulty molecules – that’ll be a major achievement.”

Before cryo-EM came on the scene, achieving such a level of detail was tricky.

“Previously, the field of structural biology has been driven primarily by one microscopy technique: x-ray crystallography,” says Professor Laurence Pearl, a Cancer Research UK-funded structural biologist from the University of Sussex.

“It’s very powerful, but it’s a challenging and unpredictable technique. It’s also limited in its ability to study fully assembled ‘biological machines’ as they work in the cell. It’s like being able to study just the engine of a car, but not how this integrates with the rest of the parts.”

This is where cryo-EM comes in.

“Now we have the ability to look at the big biological machines in the state that they operate in cells and understand how they function, and how that function is altered by genetic faults in cancer,” Pearl says.

“This understanding of structure and function speeds up our ability to discover and design new cancer drugs.”

For now, the hefty multi-million pound price tag of state-of-the art machines capable of capturing the highest levels of molecular detail means they aren’t too widely available to scientists. And this limited access has meant that the capabilities of cryo-EM have yet to be fully realised. But that’s something that Bayliss sees as an opportunity.

“Once more people have their hands on this technology, we’ll find a lot more applications for it,” he says.

“It’s allowing us to be more ambitious about the kind of work we can do and start projects we couldn’t have thought of before. It’s exciting to see what’s happening.”

Justine 

from Cancer Research UK – Science blog http://ift.tt/2xjK7ZM

Air Force Researchers Provide Rapid Answers to Big Challenges for Warfighters

The safety and protection of the warfighter is a special motivating force for this branch of the Air Force Research Laboratory.

from http://ift.tt/2y1e4Bu

The safety and protection of the warfighter is a special motivating force for this branch of the Air Force Research Laboratory.

from http://ift.tt/2y1e4Bu

Alpheratz is part of the Great Square

Alpheratz looks like one star to the eye, but spectroscopic analysis reveals that it is two stars. Image via Wikimedia Commons.

EarthSky tees are back! Learn how your purchase helps support worthy causes.

Alpheratz is one of four medium-bright stars mark the corners of an asterism – or noticeable star pattern – known as the Great Square of Pegasus. Unlike the other stars in the Great Square, Alpheratz does not belong to the constellation Pegasus. It belongs, officially, to the constellation Andromeda and in fact is designated as Alpha Andromedae. The star marks the point where Pegasus and Andromeda meet. Alpheratz can help you spot the famed Andromeda Galaxy, also known as M31, the nearest large spiral galaxy to Earth.

When can you see the star Alpheratz?

How can you use Alpheratz to help find the Andromeda Galaxy?

Science of Alpheratz

Alpheratz in star history and mythology

Alpheratz is part of the famous Great Square of Pegasus. It connects two constellations: Pegasus and Andromeda. People often find the Andromeda galaxy by star-hopping from Alpheratz to Mirach and Mu Andromedae. Mirach and Mu point to the galaxy.

When can you see the star Alpheratz? This star reaches its midnight culmination – its highest point in the sky at midnight – on October 9. So it’s generally considered an autumn star for Northern Hemisphere observers. You can see it in summertime, too, of course; it rises late at night then. And by late winter, Alpheratz is setting with the sun.

At magnitude 2.07, Alpheratz isn’t as bright as the sky’s brightest stars. You can spot it easily, except in very light-polluted areas.

View larger. | The Andromeda galaxy (upper right of photo) as seen by Ted Van at a Montana campsite in mid-August 2012. Thank you, Ted!

How can you use Alpheratz to help find the Andromeda Galaxy? The Andromeda Galaxy, also known as M31, is the nearest large spiral galaxy to Earth. It’s the most distant thing we can see with the unaided eye. You need a dark sky to see it. Autumn is a good time to look.

People often find the Andromeda galaxy by star-hopping from the star Alpheratz to two other stars in the constellation Andromeda, Mirach and Mu Andromedae. After you find those two stars, you can draw a line between them, and extend that line to find the galaxy. See the chart at the top of this post for an illustration.

Science of Alpheratz. By the best current estimates, Alpheratz is about 97 light-years away, making it a relatively nearby star. Its temperature is high – about 13,000 kelvins, more than twice that of our sun. As a result, its color is primarily blue. The bluer color also represents a relatively high energy output, probably about 200 times that of our sun.

Alpheratz appears single, but it is really two stars orbiting a common center of gravity every 97 days. We know of the binary nature of Alpheratz because its light spectrum shows two distinct sets of spectroscopic lines. The spectral class of this star is B9p. The B9 represents a star that is much hotter and more massive than our sun. The p indicating that this is a “peculiar” star. It is peculiar in the sense that its spectrum reveals an unexpected amount of manganese. It may also be peculiar due to effects of the nearby companion star.

In the mythology of the sky, Princess Andromeda was chained to a rock by the sea. Perseus, the Hero, saved her and swept her away on Pegasus, the Flying Horse. Notice the star Alpheratz near the left eye of the Princess. Click here to expand image.

Alpheratz in star history and mythology. The most interesting part of this star’s history, from our modern perspective, is its assignment to the constellation Andromeda in the 1930s by the International Astronomical Union. Prior to that, Alpheratz was often referred to as Delta Pegasi, indicating that it was the fourth-brightest star in Pegasus. But some classical star charts showed it as part of Andromeda. It was variously considered part of the constellation Pegasus, or part of the constellation Andromeda, or, by some people, part of both constellations. Today, Alpheratz is officially Alpha Andromedae, the brightest star in Andromeda.

The early Arabian stargazers certainly saw Alpheratz as part of Pegasus, not Andromeda. We know this because the name Alpheratz derives from an Arabic phrase meaning “the horse’s navel,” an obvious reference to Pegasus the Flying Horse. According to Richard Hinckley Allen in his classic book Star Names, Their Lore and Meaning, Alpheratz was called Al Surrat al Faras (the horse’s navel). That name emcompasses another name by which the star still is known today: Sirrah.

Alpheratz’s position is: RA: 00h 08m 23s, dec: +29° 05′ 27″

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Alpheratz looks like one star to the eye, but spectroscopic analysis reveals that it is two stars. Image via Wikimedia Commons.

EarthSky tees are back! Learn how your purchase helps support worthy causes.

Alpheratz is one of four medium-bright stars mark the corners of an asterism – or noticeable star pattern – known as the Great Square of Pegasus. Unlike the other stars in the Great Square, Alpheratz does not belong to the constellation Pegasus. It belongs, officially, to the constellation Andromeda and in fact is designated as Alpha Andromedae. The star marks the point where Pegasus and Andromeda meet. Alpheratz can help you spot the famed Andromeda Galaxy, also known as M31, the nearest large spiral galaxy to Earth.

When can you see the star Alpheratz?

How can you use Alpheratz to help find the Andromeda Galaxy?

Science of Alpheratz

Alpheratz in star history and mythology

Alpheratz is part of the famous Great Square of Pegasus. It connects two constellations: Pegasus and Andromeda. People often find the Andromeda galaxy by star-hopping from Alpheratz to Mirach and Mu Andromedae. Mirach and Mu point to the galaxy.

When can you see the star Alpheratz? This star reaches its midnight culmination – its highest point in the sky at midnight – on October 9. So it’s generally considered an autumn star for Northern Hemisphere observers. You can see it in summertime, too, of course; it rises late at night then. And by late winter, Alpheratz is setting with the sun.

At magnitude 2.07, Alpheratz isn’t as bright as the sky’s brightest stars. You can spot it easily, except in very light-polluted areas.

View larger. | The Andromeda galaxy (upper right of photo) as seen by Ted Van at a Montana campsite in mid-August 2012. Thank you, Ted!

How can you use Alpheratz to help find the Andromeda Galaxy? The Andromeda Galaxy, also known as M31, is the nearest large spiral galaxy to Earth. It’s the most distant thing we can see with the unaided eye. You need a dark sky to see it. Autumn is a good time to look.

People often find the Andromeda galaxy by star-hopping from the star Alpheratz to two other stars in the constellation Andromeda, Mirach and Mu Andromedae. After you find those two stars, you can draw a line between them, and extend that line to find the galaxy. See the chart at the top of this post for an illustration.

Science of Alpheratz. By the best current estimates, Alpheratz is about 97 light-years away, making it a relatively nearby star. Its temperature is high – about 13,000 kelvins, more than twice that of our sun. As a result, its color is primarily blue. The bluer color also represents a relatively high energy output, probably about 200 times that of our sun.

Alpheratz appears single, but it is really two stars orbiting a common center of gravity every 97 days. We know of the binary nature of Alpheratz because its light spectrum shows two distinct sets of spectroscopic lines. The spectral class of this star is B9p. The B9 represents a star that is much hotter and more massive than our sun. The p indicating that this is a “peculiar” star. It is peculiar in the sense that its spectrum reveals an unexpected amount of manganese. It may also be peculiar due to effects of the nearby companion star.

In the mythology of the sky, Princess Andromeda was chained to a rock by the sea. Perseus, the Hero, saved her and swept her away on Pegasus, the Flying Horse. Notice the star Alpheratz near the left eye of the Princess. Click here to expand image.

Alpheratz in star history and mythology. The most interesting part of this star’s history, from our modern perspective, is its assignment to the constellation Andromeda in the 1930s by the International Astronomical Union. Prior to that, Alpheratz was often referred to as Delta Pegasi, indicating that it was the fourth-brightest star in Pegasus. But some classical star charts showed it as part of Andromeda. It was variously considered part of the constellation Pegasus, or part of the constellation Andromeda, or, by some people, part of both constellations. Today, Alpheratz is officially Alpha Andromedae, the brightest star in Andromeda.

The early Arabian stargazers certainly saw Alpheratz as part of Pegasus, not Andromeda. We know this because the name Alpheratz derives from an Arabic phrase meaning “the horse’s navel,” an obvious reference to Pegasus the Flying Horse. According to Richard Hinckley Allen in his classic book Star Names, Their Lore and Meaning, Alpheratz was called Al Surrat al Faras (the horse’s navel). That name emcompasses another name by which the star still is known today: Sirrah.

Alpheratz’s position is: RA: 00h 08m 23s, dec: +29° 05′ 27″

from EarthSky http://ift.tt/1Mh5Ztv

Aquarius? Here’s your constellation

1948 night sky star map showing the constellations of the ancient sea imagined by the ancients in this part of the sky. The constellations here tend to be associated with water. Image via Saturated Color

Aquarius the Water Bearer is a constellation of the Zodiac, which means the sun, moon and planets all occasionally or regularly pass within its boundaries. It’s a big constellation and has long been associated with water. This constellation has no particularly bright stars, and you will need a dark sky to pick it out. Follow the links below to learn more.

How to see the constellation Aquarius

The Water Jar in Aquarius

Aquarius in history and star lore

Dates of sun’s passage through Aquarius

Another way to see the constellation Aquarius. Notice the bright star Fomalhaut below it. Image via AlltheSky

How to see the constellation Aquarius. Aquarius the Water Bearer is best seen in the evening sky during a Northern Hemisphere autumn or Southern Hemisphere spring. Aquarius appears in the southern sky as seen from northerly latitudes. South of the equator, it’s found overhead or high in the northern sky.

From either the Northern or Southern Hemisphere, you’ll see Aquarius highest in the sky in early October around 10 p.m. local time (11 p.m. local daylight saving time), or one month later – in early November – around 8 p.m. local time (9 p.m. local daylight saving time).

Aquarius is located in a region of the sky sometimes called the Sea. This part of the sky looks dark and deep, but of course there are stars here, as there are everywhere on the heavenly globe. The stars in this part of the sky tend to be faint. In western sky lore, the early stargazers associated the star patterns here with water in a celestial Sea. It’s here we find Cetus the Whale, Pisces the Fish, Eridanus the River and Piscis Austrinus the Southern Fish.

The brightest star in this “watery” region of the sky is Fomalhaut in Piscis Austrinus the Southern Fish. Aquarius the Water Carrier is usually portrayed as a man pouring a stream of water into the mouth of the Southern Fish, which is interesting since fish don’t drink water. In the sky, you’ll see a zig-zag line of stars leading from Aquarius to Fomalhaut, the only bright star in the celestial Sea. By the way, because it’s in such an apparently empty part of the sky, Fomalhaut is sometimes called the Loneliest Star.

If you know other constellations already, look for Aquarius to the northeast of the constellation Capricornus and to the southwest of the constellation Pisces.

The Water Jar in Aquarius. If your sky is dark enough, you can see a little asterism – or noticeable pattern of stars within Aquarius – marked in pink on our chart, just to the left of the star Sadal Melik. This little pattern is called the Water Jar in Aquarius. Some 30 faint stars, visible in very dark skies, make a zigzag stream of stars, flowing down toward the star Fomalhaut.

Again, you need a very dark sky to see this. We didn’t try to reproduce this zigzag line of stars here, but, in a dark sky, it is very noticeable.

The constellation Aquarius. Image via Old Book Art Image Gallery.

Aquarius in history and star lore. This ancient constellation has been associated with water throughout the Old World. But whether the abundance of water was regarded as a blessing or a curse seems to depend upon geography.

Greek mythology associates Aquarius with the deluge that wiped out all of humanity except for Deucalion and his wife Pyrrha. Zeus, the king of the gods, unleashed the flood to punish people for their misdeeds, and advised the virtuous Deucalion to save himself by building an ark. This tale of divine retribution strongly parallels the story of the great flood in the Old Testament.

In ancient Egypt, the constellation Aquarius represented Hapi, the god of the Nile River. This benevolent god distributed the waters of life, and the urn symbolized a fount of good fortune. It’s this association that explains why the Water Bearer is often seen holding the Norma Nilotica – a rod for measuring the depth of the Nile River. Also, the names of Aquarius’ two brightest stars – Sadalmelik and Sadalsuud – reaffirm the idea of providence. The names are thought to mean lucky one of the king and luckiest of the lucky.

View larger. | The constellation Aquarius to the northeast of the constellation Capricornus and the southwest of the Great Square of Pegasus.

Dates of sun’s passage through Aquarius. As seen from Earth, the sun in 2015 passes in front of the constellation Aquarius from February 16 to March 12. It is important to note that these dates are in reference to the constellation – not the sign – Aquarius. The sun is in the sign Aquarius from about January 20 to February 18.

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Bottom line: This post talks about the astronomical constellation Aquarius the Water Bearer. How to find the constellation, its famous Water Jar asterism, and a few stories about it from the ancient myths.

When does the Age of Aquarius begin?

Taurus? Here’s your constellation
Gemini? Here’s your constellation
Cancer? Here’s your constellation
Leo? Here’s your constellation
Virgo? Here’s your constellation
Libra? Here’s your constellation
Scorpius? Here’s your contellation
Sagittarius? Here’s your constellation
Capricornus? Here’s your constellation
Aquarius? Here’s your constellation
Pisces? Here’s your constellation
Aries? Here’s your constellation
Birthday late November to early December? Here’s your constellation

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1948 night sky star map showing the constellations of the ancient sea imagined by the ancients in this part of the sky. The constellations here tend to be associated with water. Image via Saturated Color

Aquarius the Water Bearer is a constellation of the Zodiac, which means the sun, moon and planets all occasionally or regularly pass within its boundaries. It’s a big constellation and has long been associated with water. This constellation has no particularly bright stars, and you will need a dark sky to pick it out. Follow the links below to learn more.

How to see the constellation Aquarius

The Water Jar in Aquarius

Aquarius in history and star lore

Dates of sun’s passage through Aquarius

Another way to see the constellation Aquarius. Notice the bright star Fomalhaut below it. Image via AlltheSky

How to see the constellation Aquarius. Aquarius the Water Bearer is best seen in the evening sky during a Northern Hemisphere autumn or Southern Hemisphere spring. Aquarius appears in the southern sky as seen from northerly latitudes. South of the equator, it’s found overhead or high in the northern sky.

From either the Northern or Southern Hemisphere, you’ll see Aquarius highest in the sky in early October around 10 p.m. local time (11 p.m. local daylight saving time), or one month later – in early November – around 8 p.m. local time (9 p.m. local daylight saving time).

Aquarius is located in a region of the sky sometimes called the Sea. This part of the sky looks dark and deep, but of course there are stars here, as there are everywhere on the heavenly globe. The stars in this part of the sky tend to be faint. In western sky lore, the early stargazers associated the star patterns here with water in a celestial Sea. It’s here we find Cetus the Whale, Pisces the Fish, Eridanus the River and Piscis Austrinus the Southern Fish.

The brightest star in this “watery” region of the sky is Fomalhaut in Piscis Austrinus the Southern Fish. Aquarius the Water Carrier is usually portrayed as a man pouring a stream of water into the mouth of the Southern Fish, which is interesting since fish don’t drink water. In the sky, you’ll see a zig-zag line of stars leading from Aquarius to Fomalhaut, the only bright star in the celestial Sea. By the way, because it’s in such an apparently empty part of the sky, Fomalhaut is sometimes called the Loneliest Star.

If you know other constellations already, look for Aquarius to the northeast of the constellation Capricornus and to the southwest of the constellation Pisces.

The Water Jar in Aquarius. If your sky is dark enough, you can see a little asterism – or noticeable pattern of stars within Aquarius – marked in pink on our chart, just to the left of the star Sadal Melik. This little pattern is called the Water Jar in Aquarius. Some 30 faint stars, visible in very dark skies, make a zigzag stream of stars, flowing down toward the star Fomalhaut.

Again, you need a very dark sky to see this. We didn’t try to reproduce this zigzag line of stars here, but, in a dark sky, it is very noticeable.

The constellation Aquarius. Image via Old Book Art Image Gallery.

Aquarius in history and star lore. This ancient constellation has been associated with water throughout the Old World. But whether the abundance of water was regarded as a blessing or a curse seems to depend upon geography.

Greek mythology associates Aquarius with the deluge that wiped out all of humanity except for Deucalion and his wife Pyrrha. Zeus, the king of the gods, unleashed the flood to punish people for their misdeeds, and advised the virtuous Deucalion to save himself by building an ark. This tale of divine retribution strongly parallels the story of the great flood in the Old Testament.

In ancient Egypt, the constellation Aquarius represented Hapi, the god of the Nile River. This benevolent god distributed the waters of life, and the urn symbolized a fount of good fortune. It’s this association that explains why the Water Bearer is often seen holding the Norma Nilotica – a rod for measuring the depth of the Nile River. Also, the names of Aquarius’ two brightest stars – Sadalmelik and Sadalsuud – reaffirm the idea of providence. The names are thought to mean lucky one of the king and luckiest of the lucky.

View larger. | The constellation Aquarius to the northeast of the constellation Capricornus and the southwest of the Great Square of Pegasus.

Dates of sun’s passage through Aquarius. As seen from Earth, the sun in 2015 passes in front of the constellation Aquarius from February 16 to March 12. It is important to note that these dates are in reference to the constellation – not the sign – Aquarius. The sun is in the sign Aquarius from about January 20 to February 18.

Enjoying EarthSky? Sign up for our free daily newsletter today!

Bottom line: This post talks about the astronomical constellation Aquarius the Water Bearer. How to find the constellation, its famous Water Jar asterism, and a few stories about it from the ancient myths.

When does the Age of Aquarius begin?

Taurus? Here’s your constellation
Gemini? Here’s your constellation
Cancer? Here’s your constellation
Leo? Here’s your constellation
Virgo? Here’s your constellation
Libra? Here’s your constellation
Scorpius? Here’s your contellation
Sagittarius? Here’s your constellation
Capricornus? Here’s your constellation
Aquarius? Here’s your constellation
Pisces? Here’s your constellation
Aries? Here’s your constellation
Birthday late November to early December? Here’s your constellation

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Anticrepuscular rays at Georgia moonrise

Photo via Scott Kuhn.

EarthSky tees are back! A percentage of the proceeds donated to selected causes. Check out the styles and colors!

Scott said:

I know we are spoiled around here, but tonight sure was pretty.

To catch a glimpse of elusive anticrepuscular rays in your sky: Next time you see crepuscular rays – sunrays – at sunrise or sunset, turn around.

Here’s more about anticrepuscular rays

Bottom line: Photo of anticrepuscular rays at moonrise.

from EarthSky http://ift.tt/2hMVzez

Photo via Scott Kuhn.

EarthSky tees are back! A percentage of the proceeds donated to selected causes. Check out the styles and colors!

Scott said:

I know we are spoiled around here, but tonight sure was pretty.

To catch a glimpse of elusive anticrepuscular rays in your sky: Next time you see crepuscular rays – sunrays – at sunrise or sunset, turn around.

Here’s more about anticrepuscular rays

Bottom line: Photo of anticrepuscular rays at moonrise.

from EarthSky http://ift.tt/2hMVzez

On October 5, the Harvest Moon

Photo at top: Harvest Moon and Earth’s shadow, by Susan Gies Jensen in Odessa, Washington.

Tonight – October 5, 2017 – that full moon you’ll see ascending in the east after sunset is the Northern Hemisphere’s Harvest Moon.

Over the years, we’ve seen lots of informal uses of the term Harvest Moon. Some people (in the Northern Hemisphere) call the full moons of September and October by that name. And that’s fine. For the few months around the autumn equinox – both September and October for us in the Northern Hemisphere – the time of moonrise is close to the time of sunset for several evenings in a row, around the time of full moon. It’s as if there are a few full moons in a row during each autumn month.

Astronomers are scientists, though, and it’s no surprise that, to them, the term full moon or the name Harvest Moon means something very specific. To astronomers, the Harvest Moon is the full moon closest to the September equinox, and full moon comes at the instant when the moon is 180^o from the sun in ecliptic – or celestial – longitude.

In 2017, this equinox took place on September 22.

The closest full moon to the autumn equinox reaches the crest of its full phase on October 5 at 18:40 UTC. For us in the continental U.S., the moon turns precisely full during the daytime hours on Thursday, October 5. By U.S. clocks, that full moon instant comes at 2:40 p.m. Eastern Daylight Time, 1:40 p.m. Central Daylight Time, 12:40 p.m. Mountain Daylight Time, 11:40 a.m. Pacific Daylight Time, 10:40 a.m. Alaskan Daylight Time and 8:40 a.m.Hawaiian Standard Time.

But don’t worry too much about the instant of full moon, or the time on your clock, or even where you are on the globe. No matter where you live worldwide, you’ll see a full-looking moon shining from dusk until dawn on the night of October 5.

Tonight’s October Harvest Moon rises in the east around sunset, climbs highest up around midnight and sets in the west around sunrise. At the vicinity of full moon, the moon – as always – stays out all night long.

Is tonight’s moon the Harvest Moon? It sure is – at least for the Northern Hemisphere!

Meanwhile, for the Southern hemisphere, this is the first full moon of spring.

Day and night sides of Earth at the instant of full moon (2017 October 5 at 18:40 Universal Time) via Earth and Moon Viewer. The shadow line at left represents sunset October 5, and the shadow line at right depicts sunrise October 6.

Moonrise over Smoke Lake, Algonquin Park, Ontario, Huntsville Canada, from EarthSky Facebook friend Adam Falardeau.

What’s the big deal about the Harvest Moon? Why are the full moons special in autumn? Around the time of the autumn equinox, the ecliptic – or the path of the sun, moon, and planets – makes a narrow angle with the horizon at sunset.

Every full moon rises around the time of sunset, and on average each successive moonrise comes about 50 minutes later daily. But, on September and October evenings – because of the narrow angle of the ecliptic to the horizon – the moon rises sooner than the average.

So, instead of rising 50 minutes later in the days after full moon, the waning gibbous moon might rise only 35 minutes later, or thereabouts, for several days in a row (at mid-northern latitudes). At far northern latitudes – like at Fairbanks, Alaska – the moon rises about 15 minutes later for days on end.

That fact was important to people in earlier times. For farmers bringing in the harvest, before the days of tractor lights, it meant there was no long period of darkness between sunset and moonrise for several days after full moon. And that meant farmers could work on in the fields, bringing in the crops by moonlight. Hence the name Harvest Moon.

At our mid-northern latitudes, watch for the Harvest Moon to shine from dusk until dawn for the next few to several days.

Bottom line: Enjoy the 2017 Harvest Moon!

Become an EarthSky friend on Facebook!

from EarthSky http://ift.tt/QAS2ty

Photo at top: Harvest Moon and Earth’s shadow, by Susan Gies Jensen in Odessa, Washington.

Tonight – October 5, 2017 – that full moon you’ll see ascending in the east after sunset is the Northern Hemisphere’s Harvest Moon.

Over the years, we’ve seen lots of informal uses of the term Harvest Moon. Some people (in the Northern Hemisphere) call the full moons of September and October by that name. And that’s fine. For the few months around the autumn equinox – both September and October for us in the Northern Hemisphere – the time of moonrise is close to the time of sunset for several evenings in a row, around the time of full moon. It’s as if there are a few full moons in a row during each autumn month.

Astronomers are scientists, though, and it’s no surprise that, to them, the term full moon or the name Harvest Moon means something very specific. To astronomers, the Harvest Moon is the full moon closest to the September equinox, and full moon comes at the instant when the moon is 180^o from the sun in ecliptic – or celestial – longitude.

In 2017, this equinox took place on September 22.

The closest full moon to the autumn equinox reaches the crest of its full phase on October 5 at 18:40 UTC. For us in the continental U.S., the moon turns precisely full during the daytime hours on Thursday, October 5. By U.S. clocks, that full moon instant comes at 2:40 p.m. Eastern Daylight Time, 1:40 p.m. Central Daylight Time, 12:40 p.m. Mountain Daylight Time, 11:40 a.m. Pacific Daylight Time, 10:40 a.m. Alaskan Daylight Time and 8:40 a.m.Hawaiian Standard Time.

But don’t worry too much about the instant of full moon, or the time on your clock, or even where you are on the globe. No matter where you live worldwide, you’ll see a full-looking moon shining from dusk until dawn on the night of October 5.

Tonight’s October Harvest Moon rises in the east around sunset, climbs highest up around midnight and sets in the west around sunrise. At the vicinity of full moon, the moon – as always – stays out all night long.

Is tonight’s moon the Harvest Moon? It sure is – at least for the Northern Hemisphere!

Meanwhile, for the Southern hemisphere, this is the first full moon of spring.

Day and night sides of Earth at the instant of full moon (2017 October 5 at 18:40 Universal Time) via Earth and Moon Viewer. The shadow line at left represents sunset October 5, and the shadow line at right depicts sunrise October 6.

Moonrise over Smoke Lake, Algonquin Park, Ontario, Huntsville Canada, from EarthSky Facebook friend Adam Falardeau.

What’s the big deal about the Harvest Moon? Why are the full moons special in autumn? Around the time of the autumn equinox, the ecliptic – or the path of the sun, moon, and planets – makes a narrow angle with the horizon at sunset.

Every full moon rises around the time of sunset, and on average each successive moonrise comes about 50 minutes later daily. But, on September and October evenings – because of the narrow angle of the ecliptic to the horizon – the moon rises sooner than the average.

So, instead of rising 50 minutes later in the days after full moon, the waning gibbous moon might rise only 35 minutes later, or thereabouts, for several days in a row (at mid-northern latitudes). At far northern latitudes – like at Fairbanks, Alaska – the moon rises about 15 minutes later for days on end.

That fact was important to people in earlier times. For farmers bringing in the harvest, before the days of tractor lights, it meant there was no long period of darkness between sunset and moonrise for several days after full moon. And that meant farmers could work on in the fields, bringing in the crops by moonlight. Hence the name Harvest Moon.

At our mid-northern latitudes, watch for the Harvest Moon to shine from dusk until dawn for the next few to several days.

Bottom line: Enjoy the 2017 Harvest Moon!

Become an EarthSky friend on Facebook!

from EarthSky http://ift.tt/QAS2ty