Leonid meteors peak next 2 mornings

The famous Leonid meteor shower is peaking over the next couple of mornings, Friday, November 17 and Saturday, November 18. To see the optimum number of meteors, no matter where you live on the globe, try watching between midnight and dawn. Here’s the good news. The new moon on November 18 will provide deliciously dark skies for the 2017 Leonid meteor shower

Will you see what’s shown on the image at the top of this post? Thousands of meteors per hour? No. That image is from 1998, when the Leonids parent comet – Comet Temple-Tuttle – was nearby. The Leonids are famous for producing meteor storms when the comet is in our neighborhood, but no meteor storm is expected this year, only a modest 10 to 15 Leonid meteors per hour.

Radiant of the Leonid meteor shower near the star Algeiba in the constellation Leo.

Here’s a tip: be aware of the rising time of the shower’s radiant point. As darkness falls in mid-November, the radiant point of the Leonid shower sits below your horizon, as seen from all parts of Earth. As the Earth turns, the constellation Leo the Lion – carrying the meteor shower radiant point – will rise over your eastern horizon around midnight (or around 1 a.m. at temperate latitudes in the Southern Hemisphere).

The Leonid meteors are few and far between around midnight, when the radiant point is at or near the horizon.

But the constellation Leo the Lion will climb upward in the sky during the hours after midnight. It reaches its highest point in the night sky just before dawn. That’s why you’ll see more meteors in the predawn sky. The higher that Leo appears in your sky, the more meteors that you’re likely to see.

Just remember, you don’t have to locate a meteor shower radiant to watch the meteor shower. The meteors will appear in all parts of the sky. But if you trace the Leonid meteors backward, they appear to come from the constellation .

All is not lost in the evening hours, by the way! Evening is the best time to try to catch a rare earthgrazer – a slow-moving and long-lasting meteor that travels horizontally across the sky.

EarthSky lunar calendars make great gifts for astronomy-minded friends and family.

What else can you see on the night of the 2017 Leonids peak?

The radiant for the Leonids is near the star Algieba in Leo. This is not Leo the Lion’s brightest star. That distinction goes to Leo’s star Regulus. Both Algieba and Regulus belong to a noticeable pattern on the sky’s dome, in the shape of a backwards question mark. This pattern is called “the Sickle.” The paths of Leonid meteors can be traced backwards to the Sickle pattern, which is a famous asterism – or noticeable star pattern – within the constellation Leo.

Watch for both of these stars. And, during the predawn/dawn hours, look for the line-up of planets in the eastern sky: Mars, Jupiter and Venus.

After a night of meteor watching, watch for the line-up of planets (Mars, Jupiter and Venus) to beautify the morning twilight. You might – or might not – spot the moon near Venus before sunrise on Friday, November 17, 2017.

By the way, the Leonids are a fast-moving meteor stream. The meteors hit the Earth’s atmosphere at some 45 miles per second (72 km/second)! The Leonid meteor shower is known for having bright meteors or fireballs, which can punch into the atmosphere with the kinetic energy of a car hitting at 60 miles per second (nearly 100 km/second).

Bottom line: In 2017, the Leonid meteor shower is expected to be at its best before dawn on Friday, November 17 and Saturday, November 18. Usually the most meteors fall in the dark hours before dawn.

EarthSky’s top 10 tips for meteor-watchers

EarthSky’s meteor shower guide for 2017

Donate: Your support means the world to us

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

The famous Leonid meteor shower is peaking over the next couple of mornings, Friday, November 17 and Saturday, November 18. To see the optimum number of meteors, no matter where you live on the globe, try watching between midnight and dawn. Here’s the good news. The new moon on November 18 will provide deliciously dark skies for the 2017 Leonid meteor shower

Will you see what’s shown on the image at the top of this post? Thousands of meteors per hour? No. That image is from 1998, when the Leonids parent comet – Comet Temple-Tuttle – was nearby. The Leonids are famous for producing meteor storms when the comet is in our neighborhood, but no meteor storm is expected this year, only a modest 10 to 15 Leonid meteors per hour.

Radiant of the Leonid meteor shower near the star Algeiba in the constellation Leo.

Here’s a tip: be aware of the rising time of the shower’s radiant point. As darkness falls in mid-November, the radiant point of the Leonid shower sits below your horizon, as seen from all parts of Earth. As the Earth turns, the constellation Leo the Lion – carrying the meteor shower radiant point – will rise over your eastern horizon around midnight (or around 1 a.m. at temperate latitudes in the Southern Hemisphere).

The Leonid meteors are few and far between around midnight, when the radiant point is at or near the horizon.

But the constellation Leo the Lion will climb upward in the sky during the hours after midnight. It reaches its highest point in the night sky just before dawn. That’s why you’ll see more meteors in the predawn sky. The higher that Leo appears in your sky, the more meteors that you’re likely to see.

Just remember, you don’t have to locate a meteor shower radiant to watch the meteor shower. The meteors will appear in all parts of the sky. But if you trace the Leonid meteors backward, they appear to come from the constellation .

All is not lost in the evening hours, by the way! Evening is the best time to try to catch a rare earthgrazer – a slow-moving and long-lasting meteor that travels horizontally across the sky.

EarthSky lunar calendars make great gifts for astronomy-minded friends and family.

What else can you see on the night of the 2017 Leonids peak?

The radiant for the Leonids is near the star Algieba in Leo. This is not Leo the Lion’s brightest star. That distinction goes to Leo’s star Regulus. Both Algieba and Regulus belong to a noticeable pattern on the sky’s dome, in the shape of a backwards question mark. This pattern is called “the Sickle.” The paths of Leonid meteors can be traced backwards to the Sickle pattern, which is a famous asterism – or noticeable star pattern – within the constellation Leo.

Watch for both of these stars. And, during the predawn/dawn hours, look for the line-up of planets in the eastern sky: Mars, Jupiter and Venus.

After a night of meteor watching, watch for the line-up of planets (Mars, Jupiter and Venus) to beautify the morning twilight. You might – or might not – spot the moon near Venus before sunrise on Friday, November 17, 2017.

By the way, the Leonids are a fast-moving meteor stream. The meteors hit the Earth’s atmosphere at some 45 miles per second (72 km/second)! The Leonid meteor shower is known for having bright meteors or fireballs, which can punch into the atmosphere with the kinetic energy of a car hitting at 60 miles per second (nearly 100 km/second).

Bottom line: In 2017, the Leonid meteor shower is expected to be at its best before dawn on Friday, November 17 and Saturday, November 18. Usually the most meteors fall in the dark hours before dawn.

EarthSky’s top 10 tips for meteor-watchers

EarthSky’s meteor shower guide for 2017

Donate: Your support means the world to us

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

November’s Leonid meteor shower

Leonid meteors, viewed from space in 1997. Image via NASA

November’s wonderful Leonid meteor shower happens every year Around November 17 or 18, as our world crosses the orbital path of Comet Tempel-Tuttle. Like many comets, Tempel-Tuttle litters its orbit with bits of debris. It’s when this cometary debris enters Earth’s atmosphere, and vaporizes, that we see the Leonid meteor shower. In 2017, the peak night of the shower is expected from midnight to dawn on Friday and Saturday mornings (November 17 and 18). Best yet, there is no moon to intrude on the Leonid meteor shower in 2017. Although this shower is known for its periodic storms, no Leonid storm is expected this year. Follow the links below to learn more:

How many Leonid meteors will you see in 2017?

When should you watch for Leonid meteors in 2017?

Where should you watch the meteor shower?

Which direction should I look to see the Leonids?

Will the Leonids produce a meteor storm in 2017?

Live by the moon! Order your 2018 EarthSky moon calendar today!

James Younger sent in this photos during the 2015 peak of the Leonid meteor shower. It’s a meteor over the San Juan Islands in the Pacific Northwest, between the U.S. mainland and Vancouver Island, British Columbia.

How many Leonid meteors will you see in 2017? The answer as always depends on when you watch, and the clarity and darkness of your night sky. This shower has been known to produce meteor storms, but no Leonid storm is expected this year. The Leonids are usually a modest shower, with typical rates of about 10 to 15 meteors per hour at the peak, in the darkness before dawn. The new moon on November 18 guarantees a dark sky for this year’s Leonid shower.

When should you watch for Leonid meteors in 2017? Knowing what time to watch is easy. As with most meteor showers, the best time to watch the Leonids is usually between the hours of midnight and dawn. The expected peak morning is Friday, November 17 or Saturday, November 18. That’s the mornings (not the evenings) of the November 17 and 18.

Can you see a meteor in bright moonlight? Yes, if it’s bright enough. Photo taken in late October 2016 by Eliot Herman in Tucson, Arizona. Bright moonlight will surely drown out many Leonid meteors in 2016, but, if you watch, you might catch one!

Where should you watch the meteor shower? We hear lots of reports from people who see meteors from yards, decks, streets and especially highways in and around cities. But the best place to watch a meteor shower is always in the country. Just go far enough from town that glittering stars, the same stars drowned by city lights, begin to pop into view.

Find a place to watch – or recommend a place – at EarthSky’s brand-new Best Places to Stargaze page.

City, state and national parks are often great places to watch meteor showers. Try googling the name of your state or city with the words city park, state park or national park. Then, be sure to go to the park early in the day and find a wide open area with a good view of the sky in all directions.

When night falls, you’ll probably be impatient to see meteors. But remember that the shower is best after midnight. Catch a nap in early evening if you can. After midnight, lie back comfortably and watch as best you can in all parts of the sky.

Sometimes friends like to watch together, facing different directions. When somebody sees one, they can call out meteor! Then everyone can quickly turn to get a glimpse.

Regulus, the brightest star in the constellation Leo the Lion, dots a backwards question mark of stars known as the Sickle. If you trace all the Leonid meteors backward, they appear to radiate from this area of the sky.

Which direction should I look to see the Leonids? Meteors in annual showers are named for the point in our sky from which they appear to radiate. This shower is named for the constellation Leo the Lion, because these meteors radiate outward from the vicinity of stars representing the Lion’s mane.

If you trace the paths of Leonid meteors backward on the sky’s dome, they do seem to stream from near the star Algieba in the constellation Leo. The point in the sky from which they appear to radiate is called the radiant point. This radiant point is an optical illusion. It’s like standing on railroad tracks and peering off into the distance to see the tracks converge. The illusion of the radiant point is caused by the fact that the meteors – much like the railroad tracks – are moving on parallel paths.

In recent years, people have gotten the mistaken idea that you must know the whereabouts of a meteor shower’s radiant point in order to watch the meteor shower. You don’t need to. The meteors often don’t become visible until they are 30 degrees or so from their radiant point. They are streaking out from the radiant in all directions.

Thus the Leonid meteors – like meteors in all annual showers – will appear in all parts of the sky.

Old woodcuts depicting 1833 Leonid meteor storm.

Will the Leonids produce a meteor storm in 2017? No. Not this year. Most astronomers say you need more than 1,000 meteors an hour to consider a shower as a storm. That’s a far cry from the 10 to 15 meteors per hour predicted for this year. Still, seeing even one bright meteor can make your night.

The Leonid shower is known for producing meteor storms, though. The parent comet – Tempel-Tuttle – completes a single orbit around the sun about once every 33 years. It releases fresh material every time it enters the inner solar system and approaches the sun. Since the 19th century, skywatchers have watched for Leonid meteor storms about every 33 years, beginning with the meteor storm of 1833, said to produce more than 100,000 meteors an hour.

The next great Leonid storms were seen about 33 years later, in 1866 and 1867.

Then a meteor storm was predicted for 1899, but did not materialize.

It wasn’t until 1966 that the next spectacular Leonid storm was seen, this time over the Americas. In 1966, observers in the southwest United States reported seeing 40 to 50 meteors per second (that’s 2,400 to 3,000 meteors per minute!) during a span of 15 minutes on the morning of November 17, 1966.

In 2001, another great Leonid meteor storm occurred. Spaceweather.com reported:

The display began on Sunday morning, November 18, when Earth glided into a dust cloud shed by comet Tempel-Tuttle in 1766. Thousands of meteors per hour rained over North America and Hawaii. Then, on Monday morning November 19 (local time in Asia), it happened again: Earth entered a second cometary debris cloud from Tempel-Tuttle. Thousands more Leonids then fell over east Asian countries and Australia.

View SpaceWeather’s 2001 Leonid meteor gallery.

Bottom line: If you want to watch the 2017 Leonid meteor shower, just know that the new moon will guarantee a dark night for meteor watching. The greatest number of meteors usually fall in the dark hours before dawn.

EarthSky’s meteor shower guide for 2017

Don’t miss anything. Sign up for EarthSky News by email

Easily locate stars and constellations during any day and time with EarthSky’s Planisphere.

from EarthSky http://ift.tt/2f0CXUv

Leonid meteors, viewed from space in 1997. Image via NASA

November’s wonderful Leonid meteor shower happens every year Around November 17 or 18, as our world crosses the orbital path of Comet Tempel-Tuttle. Like many comets, Tempel-Tuttle litters its orbit with bits of debris. It’s when this cometary debris enters Earth’s atmosphere, and vaporizes, that we see the Leonid meteor shower. In 2017, the peak night of the shower is expected from midnight to dawn on Friday and Saturday mornings (November 17 and 18). Best yet, there is no moon to intrude on the Leonid meteor shower in 2017. Although this shower is known for its periodic storms, no Leonid storm is expected this year. Follow the links below to learn more:

How many Leonid meteors will you see in 2017?

When should you watch for Leonid meteors in 2017?

Where should you watch the meteor shower?

Which direction should I look to see the Leonids?

Will the Leonids produce a meteor storm in 2017?

Live by the moon! Order your 2018 EarthSky moon calendar today!

James Younger sent in this photos during the 2015 peak of the Leonid meteor shower. It’s a meteor over the San Juan Islands in the Pacific Northwest, between the U.S. mainland and Vancouver Island, British Columbia.

How many Leonid meteors will you see in 2017? The answer as always depends on when you watch, and the clarity and darkness of your night sky. This shower has been known to produce meteor storms, but no Leonid storm is expected this year. The Leonids are usually a modest shower, with typical rates of about 10 to 15 meteors per hour at the peak, in the darkness before dawn. The new moon on November 18 guarantees a dark sky for this year’s Leonid shower.

When should you watch for Leonid meteors in 2017? Knowing what time to watch is easy. As with most meteor showers, the best time to watch the Leonids is usually between the hours of midnight and dawn. The expected peak morning is Friday, November 17 or Saturday, November 18. That’s the mornings (not the evenings) of the November 17 and 18.

Can you see a meteor in bright moonlight? Yes, if it’s bright enough. Photo taken in late October 2016 by Eliot Herman in Tucson, Arizona. Bright moonlight will surely drown out many Leonid meteors in 2016, but, if you watch, you might catch one!

Where should you watch the meteor shower? We hear lots of reports from people who see meteors from yards, decks, streets and especially highways in and around cities. But the best place to watch a meteor shower is always in the country. Just go far enough from town that glittering stars, the same stars drowned by city lights, begin to pop into view.

Find a place to watch – or recommend a place – at EarthSky’s brand-new Best Places to Stargaze page.

City, state and national parks are often great places to watch meteor showers. Try googling the name of your state or city with the words city park, state park or national park. Then, be sure to go to the park early in the day and find a wide open area with a good view of the sky in all directions.

When night falls, you’ll probably be impatient to see meteors. But remember that the shower is best after midnight. Catch a nap in early evening if you can. After midnight, lie back comfortably and watch as best you can in all parts of the sky.

Sometimes friends like to watch together, facing different directions. When somebody sees one, they can call out meteor! Then everyone can quickly turn to get a glimpse.

Regulus, the brightest star in the constellation Leo the Lion, dots a backwards question mark of stars known as the Sickle. If you trace all the Leonid meteors backward, they appear to radiate from this area of the sky.

Which direction should I look to see the Leonids? Meteors in annual showers are named for the point in our sky from which they appear to radiate. This shower is named for the constellation Leo the Lion, because these meteors radiate outward from the vicinity of stars representing the Lion’s mane.

If you trace the paths of Leonid meteors backward on the sky’s dome, they do seem to stream from near the star Algieba in the constellation Leo. The point in the sky from which they appear to radiate is called the radiant point. This radiant point is an optical illusion. It’s like standing on railroad tracks and peering off into the distance to see the tracks converge. The illusion of the radiant point is caused by the fact that the meteors – much like the railroad tracks – are moving on parallel paths.

In recent years, people have gotten the mistaken idea that you must know the whereabouts of a meteor shower’s radiant point in order to watch the meteor shower. You don’t need to. The meteors often don’t become visible until they are 30 degrees or so from their radiant point. They are streaking out from the radiant in all directions.

Thus the Leonid meteors – like meteors in all annual showers – will appear in all parts of the sky.

Old woodcuts depicting 1833 Leonid meteor storm.

Will the Leonids produce a meteor storm in 2017? No. Not this year. Most astronomers say you need more than 1,000 meteors an hour to consider a shower as a storm. That’s a far cry from the 10 to 15 meteors per hour predicted for this year. Still, seeing even one bright meteor can make your night.

The Leonid shower is known for producing meteor storms, though. The parent comet – Tempel-Tuttle – completes a single orbit around the sun about once every 33 years. It releases fresh material every time it enters the inner solar system and approaches the sun. Since the 19th century, skywatchers have watched for Leonid meteor storms about every 33 years, beginning with the meteor storm of 1833, said to produce more than 100,000 meteors an hour.

The next great Leonid storms were seen about 33 years later, in 1866 and 1867.

Then a meteor storm was predicted for 1899, but did not materialize.

It wasn’t until 1966 that the next spectacular Leonid storm was seen, this time over the Americas. In 1966, observers in the southwest United States reported seeing 40 to 50 meteors per second (that’s 2,400 to 3,000 meteors per minute!) during a span of 15 minutes on the morning of November 17, 1966.

In 2001, another great Leonid meteor storm occurred. Spaceweather.com reported:

The display began on Sunday morning, November 18, when Earth glided into a dust cloud shed by comet Tempel-Tuttle in 1766. Thousands of meteors per hour rained over North America and Hawaii. Then, on Monday morning November 19 (local time in Asia), it happened again: Earth entered a second cometary debris cloud from Tempel-Tuttle. Thousands more Leonids then fell over east Asian countries and Australia.

View SpaceWeather’s 2001 Leonid meteor gallery.

Bottom line: If you want to watch the 2017 Leonid meteor shower, just know that the new moon will guarantee a dark night for meteor watching. The greatest number of meteors usually fall in the dark hours before dawn.

EarthSky’s meteor shower guide for 2017

Don’t miss anything. Sign up for EarthSky News by email

Easily locate stars and constellations during any day and time with EarthSky’s Planisphere.

from EarthSky http://ift.tt/2f0CXUv

How tiger sharks are helping seagrass

A tiger shark swimming above seagrass. Image via Florida International University.

A heatwave along Australia’s western coast in 2011 killed off many of the region’s treasured seagrass beds. While recovery of the marine ecosystem has been slow, scientists have discovered that tiger sharks are aiding in the regrowth of seagrass beds by scaring off grazers such as dugongs.

Seagrass beds support high levels of biodiversity. They also store vast amounts of carbon—known as blue carbon—and help to offset greenhouse gas emissions and climate change much like tropical forests. Shark Bay, Australia, is home to some of the most extensive and pristine seagrass beds around the world. Common inhabitants of Shark Bay include tiger sharks, dugongs, and sea turtles.

A dugong grazing on seagrass. Image via Ruth Hartnup.

In 2011, water temperatures soared to 2 to 4 degrees Celsius (3.6 to 7.2 degrees Fahrenheit) above normal along the western coast of Australia for a period of two months, and this event killed off vast amounts of seagrass in Shark Bay. Losses in seagrass cover amounted to more than 90% in many areas, according to a study published in the journal Marine Ecology Progress Series on March 13, 2017.

The dominant seagrass species, commonly known as wire weed (Amphibolis antarctica), was the hardest hit. By 2014, three years after the heatwave, the wire weed had still not recovered. However, another fast growing seagrass species (Halodule uninervis) was beginning to take root in the marine sands. As the former species is a temperate seagrass and the latter is a tropical seagrass, future shifts away from the once dominant cool-water adapted species are possible if warmer waters persist, the scientists say.

Research on the recovery of seagrass in Shark Bay is continuing thanks to funding support from the National Science Foundation. In a July 26, 2017, news release, the scientists reported that tiger sharks were having a marked influence on the recovery of seagrass beds. Specifically, they found that new seagrass growth was higher in the areas where the sharks roamed. The presence of sharks can scare off animals that graze heavily on seagrass, like dugongs, and so seagrass can grow better in areas where grazers are not as abundant.

This new research is being led by Michael Heithaus, a marine scientist at Florida International University, who commented on the preliminary results in the news release. He said:

Just the fear of sharks can be enough, in many cases, to keep a marine ecosystem healthy and able to respond to stresses.

The new research represents another fascinating example of the importance of top predators to ecosystem health. If you haven’t seen it already, check out the beautiful video below on how wolves are helping to shape Yellowstone National Park. The video was created by Sustainable Human and has been viewed over 38 million times.

These studies on wolves and sharks are helping to illustrate the profound links among diverse species in the environment. To ensure the sustainability of the environment, humans need to become more aware of such interconnectedness among species.

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

Donate to EarthSky: Your support means the world to us

Bottom line: New research has discovered that tiger sharks are helping seagrass beds to recover following a deadly 2011 heatwave in Shark Bay, Australia.

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A tiger shark swimming above seagrass. Image via Florida International University.

A heatwave along Australia’s western coast in 2011 killed off many of the region’s treasured seagrass beds. While recovery of the marine ecosystem has been slow, scientists have discovered that tiger sharks are aiding in the regrowth of seagrass beds by scaring off grazers such as dugongs.

Seagrass beds support high levels of biodiversity. They also store vast amounts of carbon—known as blue carbon—and help to offset greenhouse gas emissions and climate change much like tropical forests. Shark Bay, Australia, is home to some of the most extensive and pristine seagrass beds around the world. Common inhabitants of Shark Bay include tiger sharks, dugongs, and sea turtles.

A dugong grazing on seagrass. Image via Ruth Hartnup.

In 2011, water temperatures soared to 2 to 4 degrees Celsius (3.6 to 7.2 degrees Fahrenheit) above normal along the western coast of Australia for a period of two months, and this event killed off vast amounts of seagrass in Shark Bay. Losses in seagrass cover amounted to more than 90% in many areas, according to a study published in the journal Marine Ecology Progress Series on March 13, 2017.

The dominant seagrass species, commonly known as wire weed (Amphibolis antarctica), was the hardest hit. By 2014, three years after the heatwave, the wire weed had still not recovered. However, another fast growing seagrass species (Halodule uninervis) was beginning to take root in the marine sands. As the former species is a temperate seagrass and the latter is a tropical seagrass, future shifts away from the once dominant cool-water adapted species are possible if warmer waters persist, the scientists say.

Research on the recovery of seagrass in Shark Bay is continuing thanks to funding support from the National Science Foundation. In a July 26, 2017, news release, the scientists reported that tiger sharks were having a marked influence on the recovery of seagrass beds. Specifically, they found that new seagrass growth was higher in the areas where the sharks roamed. The presence of sharks can scare off animals that graze heavily on seagrass, like dugongs, and so seagrass can grow better in areas where grazers are not as abundant.

This new research is being led by Michael Heithaus, a marine scientist at Florida International University, who commented on the preliminary results in the news release. He said:

Just the fear of sharks can be enough, in many cases, to keep a marine ecosystem healthy and able to respond to stresses.

The new research represents another fascinating example of the importance of top predators to ecosystem health. If you haven’t seen it already, check out the beautiful video below on how wolves are helping to shape Yellowstone National Park. The video was created by Sustainable Human and has been viewed over 38 million times.

These studies on wolves and sharks are helping to illustrate the profound links among diverse species in the environment. To ensure the sustainability of the environment, humans need to become more aware of such interconnectedness among species.

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

Donate to EarthSky: Your support means the world to us

Bottom line: New research has discovered that tiger sharks are helping seagrass beds to recover following a deadly 2011 heatwave in Shark Bay, Australia.

from EarthSky http://ift.tt/2yFGxL8

Earth’s shadow

Image via Alice McClure.

The Earth’s shadow extends about 860,000 miles into outer space. That distance is the equivalent of about 109 Earth diameters or one sun diameter, or better than three times the moon’s distance from Earth.

A viewer wrote:

It’s hard to understand this as a shadow. Is it comparable to a shadow as we usually think of it? I guess it seems funny that it is projected onto…..space.

EarthSky’s Bruce McClure replied:

Yes, comparable to a shadow as we usually think of, though on a much larger scale. During the nighttime, we’re actually sitting in the Earth’s own shadow. Given clear skies, you can watch the Earth’s shadow rising upward in the east as the sun falls farther beneath the horizon in the west. Or if you’re up before sunrise, you can watch the Earth’s shadow sinking in the west as the sun climbs upward toward the eastern horizon.

Learn more about Earth’s shadow

Bottom line: Alice McClure captured this image of Earth’s shadow on November 8, 2015.

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Image via Alice McClure.

The Earth’s shadow extends about 860,000 miles into outer space. That distance is the equivalent of about 109 Earth diameters or one sun diameter, or better than three times the moon’s distance from Earth.

A viewer wrote:

It’s hard to understand this as a shadow. Is it comparable to a shadow as we usually think of it? I guess it seems funny that it is projected onto…..space.

EarthSky’s Bruce McClure replied:

Yes, comparable to a shadow as we usually think of, though on a much larger scale. During the nighttime, we’re actually sitting in the Earth’s own shadow. Given clear skies, you can watch the Earth’s shadow rising upward in the east as the sun falls farther beneath the horizon in the west. Or if you’re up before sunrise, you can watch the Earth’s shadow sinking in the west as the sun climbs upward toward the eastern horizon.

Learn more about Earth’s shadow

Bottom line: Alice McClure captured this image of Earth’s shadow on November 8, 2015.

from EarthSky http://ift.tt/2zJ7YqT

Don’t miss moon, Venus, Jupiter at dawn

Before sunup on November 16, 2017, find an unobstructed horizon in the direction of sunrise to get the best view of the waning crescent moon, plus the sky’s two brightest planets, Venus and Jupiter. They’ll be extremely low in the east at sunup, and an unobstructed horizon – and clear sky to the horizon – will definitely be needed. And even if you have those two prerequisites – clear sky, open horizon – whether you see them or not depends on your latitude on Earth’s globe. Keep binoculars handy. A telephoto lens will also pick them up, and, in fact, this is a wonderful photo opportunity.

From around the world on November 16, the slender waning crescent moon rises in the east first, followed by Jupiter and then Venus. At mid-northern latitudes – like those in the U.S. and Europe – Venus rises better than an hour before the sun.

At the equator, Venus comes up about 50 minutes before sunrise; and at temperate latitudes in the Southern Hemisphere, Venus rises only about 35 minutes before sunrise.

Click here for a recommended almanac to find the rising times of the moon, Jupiter and Venus in your sky.

If you’ve been watching the morning sky lately, you might have seen the waning crescent moon swinging past Mars the last several mornings. Jupiter and Venus next!

The lit side of the moon points in the direction of Jupiter and Venus, giving you a good idea of where to look for them. If you are at a very southerly latitude on Earth, you can always use binoculars to seek for these worlds beneath the moon in the murky glow of morning twilight. Fortunately, Venus and Jupiter rank as the brightest and second-brightest planets in Earth’s sky, respectively, so you may well see these worlds with the unaided eye, even though they’re sitting low in the twilight. Think photo opportunity!

Day by day, Venus will sink closer to the glare of sunrise, while Jupiter will climb upward, away from sunrise. Expect Venus to disappear from view in the morning sky after a few more weeks, while Jupiter will remain a fine morning object for months to come and a wonderful evening object in 2018.

In fact, if you get up before dawn on these November and December mornings, you can also view the the star Spica and the planet Mars above Jupiter. Day by day, Jupiter and Spica will climb upward to Mars in the predawn/dawn sky. Spica will catch up with Mars on November 29, 2017, and Jupiter will meet up with Mars on January 7, 2018.

View larger. | See how close Venus and Jupiter are to the sunrise now? This photo is from November 13, 2017. Doug Groenhoff wrote: “Conjunction of Jupiter and Venus over the Rincon Mountains from far northwest Tucson, Arizona. While dawn was cracking. Soon lost in clouds.” See more photos of Jupiter and Venus at conjunction on November 13.

Bottom line: On November 16, 2017, look for Jupiter and Venus beneath the waning crescent moon. They’ll be low in the east, shortly before sunup.

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Before sunup on November 16, 2017, find an unobstructed horizon in the direction of sunrise to get the best view of the waning crescent moon, plus the sky’s two brightest planets, Venus and Jupiter. They’ll be extremely low in the east at sunup, and an unobstructed horizon – and clear sky to the horizon – will definitely be needed. And even if you have those two prerequisites – clear sky, open horizon – whether you see them or not depends on your latitude on Earth’s globe. Keep binoculars handy. A telephoto lens will also pick them up, and, in fact, this is a wonderful photo opportunity.

From around the world on November 16, the slender waning crescent moon rises in the east first, followed by Jupiter and then Venus. At mid-northern latitudes – like those in the U.S. and Europe – Venus rises better than an hour before the sun.

At the equator, Venus comes up about 50 minutes before sunrise; and at temperate latitudes in the Southern Hemisphere, Venus rises only about 35 minutes before sunrise.

Click here for a recommended almanac to find the rising times of the moon, Jupiter and Venus in your sky.

If you’ve been watching the morning sky lately, you might have seen the waning crescent moon swinging past Mars the last several mornings. Jupiter and Venus next!

The lit side of the moon points in the direction of Jupiter and Venus, giving you a good idea of where to look for them. If you are at a very southerly latitude on Earth, you can always use binoculars to seek for these worlds beneath the moon in the murky glow of morning twilight. Fortunately, Venus and Jupiter rank as the brightest and second-brightest planets in Earth’s sky, respectively, so you may well see these worlds with the unaided eye, even though they’re sitting low in the twilight. Think photo opportunity!

Day by day, Venus will sink closer to the glare of sunrise, while Jupiter will climb upward, away from sunrise. Expect Venus to disappear from view in the morning sky after a few more weeks, while Jupiter will remain a fine morning object for months to come and a wonderful evening object in 2018.

In fact, if you get up before dawn on these November and December mornings, you can also view the the star Spica and the planet Mars above Jupiter. Day by day, Jupiter and Spica will climb upward to Mars in the predawn/dawn sky. Spica will catch up with Mars on November 29, 2017, and Jupiter will meet up with Mars on January 7, 2018.

View larger. | See how close Venus and Jupiter are to the sunrise now? This photo is from November 13, 2017. Doug Groenhoff wrote: “Conjunction of Jupiter and Venus over the Rincon Mountains from far northwest Tucson, Arizona. While dawn was cracking. Soon lost in clouds.” See more photos of Jupiter and Venus at conjunction on November 13.

Bottom line: On November 16, 2017, look for Jupiter and Venus beneath the waning crescent moon. They’ll be low in the east, shortly before sunup.

from EarthSky http://ift.tt/2zSw1jZ

Citizen inventors: NASA’s 3D Printed Habitat Challenge

Hey all you citizen inventors! On November 7, 2017, NASA opened team registration for Phase 3 of its 3D Printed Habitat Challenge – the On-Site Habitat Competition. Get a team together and grab this awesome opportunity to share your ideas – plus there’s a $2 million total prize purse.

If humans plan to live on Mars – and beyond – future missions won’t be able to carry all of the necessary building materials from Earth, so we’re going to need some innovative options for shelter. NASA’s 3D-Printed Habitat Challenge is looking for ways to develop technologies to create such habitats on-site, and challenges citizen inventors to lead the way.

In other words, NASA wants America’s best and brightest to help them figure out how to build a house on Mars, using advanced 3D printing technology in the most efficient and sustainable way possible.

Competition details, schedule and rules.

According to a NASA statement:

The goal of the 3D-Printed Habitat Challenge is to foster the development of new technologies necessary to additively manufacture a habitat using local indigenous materials with, or without, recyclable materials. The vision is that autonomous machines will someday be deployed to the Moon, Mars or beyond to construct shelters for human habitation.

First place winner in Phase 2: Ice house by SEArch/Clouds Architecture Office. Read more about this design here. Image via NASA.

The 3D-Printed Habitat Challenge is divided into phases. The Phase 1: Design Competition called on participants to develop state-of-the-art architectural concepts and was completed in 2015.

The Phase 2: Structural Member Competition focused on manufacturing structural components and was completed in August 2017.

The now-open Phase 3: On-Site Habitat Competition challenges competitors to fabricate sub-scale habitats using indigenous materials with or without mission-generated recyclables, and offers a $2 million total prize purse.

Mars Artificial Atmospheric Envelope (M.A.A.E.) – a finalist from Phase 2. More info about this design here. Image via NASA.

Phase 3 has five levels of competition. Interested teams may register through February 15, 2018. Find full details, schedule and rules here.

Monsi Roman is program manager of NASA’s Centennial Challenges. Roman said in a statement:

The ideas and technologies this competition has already produced are encouraging, and we are excited to see what this next phase will bring. The solutions we seek from our competitions are revolutionary, which by nature makes them extremely difficult. But this only fuels our teams to work harder to innovate and solve.

Bottom line: On November 7, 2017, NASA opened team registration for Phase 3 of its 3D Printed Habitat Challenge – the On-Site Habitat Competition

Read more from NASA

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

Hey all you citizen inventors! On November 7, 2017, NASA opened team registration for Phase 3 of its 3D Printed Habitat Challenge – the On-Site Habitat Competition. Get a team together and grab this awesome opportunity to share your ideas – plus there’s a $2 million total prize purse.

If humans plan to live on Mars – and beyond – future missions won’t be able to carry all of the necessary building materials from Earth, so we’re going to need some innovative options for shelter. NASA’s 3D-Printed Habitat Challenge is looking for ways to develop technologies to create such habitats on-site, and challenges citizen inventors to lead the way.

In other words, NASA wants America’s best and brightest to help them figure out how to build a house on Mars, using advanced 3D printing technology in the most efficient and sustainable way possible.

Competition details, schedule and rules.

According to a NASA statement:

The goal of the 3D-Printed Habitat Challenge is to foster the development of new technologies necessary to additively manufacture a habitat using local indigenous materials with, or without, recyclable materials. The vision is that autonomous machines will someday be deployed to the Moon, Mars or beyond to construct shelters for human habitation.

First place winner in Phase 2: Ice house by SEArch/Clouds Architecture Office. Read more about this design here. Image via NASA.

The 3D-Printed Habitat Challenge is divided into phases. The Phase 1: Design Competition called on participants to develop state-of-the-art architectural concepts and was completed in 2015.

The Phase 2: Structural Member Competition focused on manufacturing structural components and was completed in August 2017.

The now-open Phase 3: On-Site Habitat Competition challenges competitors to fabricate sub-scale habitats using indigenous materials with or without mission-generated recyclables, and offers a $2 million total prize purse.

Mars Artificial Atmospheric Envelope (M.A.A.E.) – a finalist from Phase 2. More info about this design here. Image via NASA.

Phase 3 has five levels of competition. Interested teams may register through February 15, 2018. Find full details, schedule and rules here.

Monsi Roman is program manager of NASA’s Centennial Challenges. Roman said in a statement:

The ideas and technologies this competition has already produced are encouraging, and we are excited to see what this next phase will bring. The solutions we seek from our competitions are revolutionary, which by nature makes them extremely difficult. But this only fuels our teams to work harder to innovate and solve.

Bottom line: On November 7, 2017, NASA opened team registration for Phase 3 of its 3D Printed Habitat Challenge – the On-Site Habitat Competition

Read more from NASA

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

Scientists find teeth of early human ancestor

Artists concept of the small rat-like mammals believed to be the earliest known ancestors of most modern mammals, including humans. Image courtesy of Dr. Mark Witton, paleo-artist, University of Portsmouth.

Scientists have come to believe that modern placental mammals – from whales to bats, and yes, humans too – descended from small furry mammals that lived during the age of the dinosaurs. On November 7, 2017, scientists announced the discovery of two fossil teeth from these ancient creatures, the earliest fossils of these creatures known so far, in rocks from the coast of Dorset in England. The teeth date back to 145 million years ago. The scientists’ statement said:

They are the earliest undisputed fossils of mammals belonging to the line that led to human beings.

The work is published the peer-reviewed journal Acta Palaeontologica Polonica.

Steve Sweetman at the University of Portsmouth is the paper’s main author. He’s an expert in small vertebrates that lived during the Cretaceous period. In his team’s statement, he recounted how an undergraduate at the university, Grant Smith, made the extraordinary discovery of two unusual fossil teeth.

Grant was sifting through small samples of earliest Cretaceous rocks collected on the coast of Dorset as part of his undergraduate dissertation project in the hope of finding some interesting remains. Quite unexpectedly he found not one but two quite remarkable teeth of a type never before seen from rocks of this age. I was asked to look at them and give an opinion and even at first glance my jaw dropped!

The teeth are of a type so highly evolved that I realized straight away I was looking at remains of Early Cretaceous mammals that more closely resembled those that lived during the latest Cretaceous – some 60 million years later in geological history.

In the world of paleontology there has been a lot of debate around a specimen found in China, which is approximately 160 million years old. This was originally said to be of the same type as ours but recent studies have ruled this out. That being the case, our 145-million-year-old teeth are undoubtedly the earliest yet known from the line of mammals that lead to our own species.

These tiny furry mammals, Sweetman believes, were probably nocturnal. To an expert’s eye, a single tooth can reveal a lot about an animal. One of the fossil teeth may have belonged to a ground burrower that probably ate insects. The other tooth may have belonged to a creature that also ate plants. Sweetman said:

The teeth are of a highly advanced type that can pierce, cut and crush food. They are also very worn which suggests the animals to which they belonged lived to a good age for their species. No mean feat when you’re sharing your habitat with predatory dinosaurs!

Stereo scanning electron micrographs of the fossil teeth. Image courtesy of University of Portsmouth.

When Grant Smith first saw the teeth, he recognized them as mammalian. His supervisor, Dave Martill, also at the University of Portsmouth, agreed but suggested they consult Sweetman. Martill later commented:

We looked at them with a microscope but despite over 30 years’ experience these teeth looked very different, and we decided we needed to bring in a third pair of eyes and more expertise in the field in the form of our colleague, Dr. Sweetman.

Steve made the connection immediately, but what I’m most pleased about is that a student who is a complete beginner was able to make a remarkable scientific discovery in palaeontology and see his discovery and his name published in a scientific paper. The Jurassic Coast is always unveiling fresh secrets and I’d like to think that similar discoveries will continue to be made right on our doorstep.

From left to right, Steve Sweetman, Grant Smith and Dave Martill. Image courtesy of University of Portsmouth.

In the video below, Steve Sweetman, Grant Smith, and Dave Martill, all from the University of Portsmouth, discuss their finding.

Man's earliest ancestors discovered in southern England from University of Portsmouth on Vimeo.

Bottom line: Scientists discover fossil teeth belonging to the earliest known ancestor of many modern-day mammals, including humans, dating back to 145 million years ago, in Dorset, England.

from EarthSky http://ift.tt/2jnvgw9

Artists concept of the small rat-like mammals believed to be the earliest known ancestors of most modern mammals, including humans. Image courtesy of Dr. Mark Witton, paleo-artist, University of Portsmouth.

Scientists have come to believe that modern placental mammals – from whales to bats, and yes, humans too – descended from small furry mammals that lived during the age of the dinosaurs. On November 7, 2017, scientists announced the discovery of two fossil teeth from these ancient creatures, the earliest fossils of these creatures known so far, in rocks from the coast of Dorset in England. The teeth date back to 145 million years ago. The scientists’ statement said:

They are the earliest undisputed fossils of mammals belonging to the line that led to human beings.

The work is published the peer-reviewed journal Acta Palaeontologica Polonica.

Steve Sweetman at the University of Portsmouth is the paper’s main author. He’s an expert in small vertebrates that lived during the Cretaceous period. In his team’s statement, he recounted how an undergraduate at the university, Grant Smith, made the extraordinary discovery of two unusual fossil teeth.

Grant was sifting through small samples of earliest Cretaceous rocks collected on the coast of Dorset as part of his undergraduate dissertation project in the hope of finding some interesting remains. Quite unexpectedly he found not one but two quite remarkable teeth of a type never before seen from rocks of this age. I was asked to look at them and give an opinion and even at first glance my jaw dropped!

The teeth are of a type so highly evolved that I realized straight away I was looking at remains of Early Cretaceous mammals that more closely resembled those that lived during the latest Cretaceous – some 60 million years later in geological history.

In the world of paleontology there has been a lot of debate around a specimen found in China, which is approximately 160 million years old. This was originally said to be of the same type as ours but recent studies have ruled this out. That being the case, our 145-million-year-old teeth are undoubtedly the earliest yet known from the line of mammals that lead to our own species.

These tiny furry mammals, Sweetman believes, were probably nocturnal. To an expert’s eye, a single tooth can reveal a lot about an animal. One of the fossil teeth may have belonged to a ground burrower that probably ate insects. The other tooth may have belonged to a creature that also ate plants. Sweetman said:

The teeth are of a highly advanced type that can pierce, cut and crush food. They are also very worn which suggests the animals to which they belonged lived to a good age for their species. No mean feat when you’re sharing your habitat with predatory dinosaurs!

Stereo scanning electron micrographs of the fossil teeth. Image courtesy of University of Portsmouth.

When Grant Smith first saw the teeth, he recognized them as mammalian. His supervisor, Dave Martill, also at the University of Portsmouth, agreed but suggested they consult Sweetman. Martill later commented:

We looked at them with a microscope but despite over 30 years’ experience these teeth looked very different, and we decided we needed to bring in a third pair of eyes and more expertise in the field in the form of our colleague, Dr. Sweetman.

Steve made the connection immediately, but what I’m most pleased about is that a student who is a complete beginner was able to make a remarkable scientific discovery in palaeontology and see his discovery and his name published in a scientific paper. The Jurassic Coast is always unveiling fresh secrets and I’d like to think that similar discoveries will continue to be made right on our doorstep.

From left to right, Steve Sweetman, Grant Smith and Dave Martill. Image courtesy of University of Portsmouth.

In the video below, Steve Sweetman, Grant Smith, and Dave Martill, all from the University of Portsmouth, discuss their finding.

Man's earliest ancestors discovered in southern England from University of Portsmouth on Vimeo.

Bottom line: Scientists discover fossil teeth belonging to the earliest known ancestor of many modern-day mammals, including humans, dating back to 145 million years ago, in Dorset, England.

from EarthSky http://ift.tt/2jnvgw9