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Meteor - Blog Posts
Greatest Hits — Craters We Love
Our solar system was built on impacts — some big, some small — some fast, some slow. This week, in honor of a possible newly-discovered large crater here on Earth, here’s a quick run through of some of the more intriguing impacts across our solar system.
1. Mercury: A Basin Bigger Than Texas
Mercury does not have a thick atmosphere to protect it from space debris. The small planet is riddled with craters, but none as spectacular as the Caloris Basin. “Basin” is what geologists call craters larger than about 186 miles (300 kilometers) in diameter. Caloris is about 950 miles (1,525 kilometers) across and is ringed by mile-high mountains.
For scale, the state of Texas is 773 miles (1,244 kilometers) wide from east to west.
2. Venus: Tough on Space Rocks
Venus’ ultra-thick atmosphere finishes off most meteors before they reach the surface. The planet’s volcanic history has erased many of its craters, but like almost any place with solid ground in our solar system, there are still impact scars to be found. Most of what we know of Venus’ craters comes from radar images provided by orbiting spacecraft, such as NASA’s Magellan.
Mead Crater is the largest known impact site on Venus. It is about 170 miles (275 kilometers) in diameter. The relatively-flat, brighter inner floor of the crater indicates it was filled with impact melt and/or lava.
3. Earth: Still Craters After All These Years
Evidence of really big impacts — such as Arizona’s Meteor Crater — are harder to find on Earth. The impact history of our home world has largely been erased by weather and water or buried under lava, rock or ice. Nonetheless, we still find new giant craters occasionally.
A NASA glaciologist has discovered a possible impact crater buried under more than a mile of ice in northwest Greenland.
This follows the finding, announced in November 2018, of a 19-mile (31-kilometer) wide crater beneath Hiawatha Glacier – the first meteorite impact crater ever discovered under Earth’s ice sheets.
If the second crater, which has a width of over 22 miles (35 kilometers), is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth.
4. Moon: Our Cratered Companion
Want to imagine what Earth might look like without its protective atmosphere, weather, water and other crater-erasing features? Look up at the Moon. The Moon’s pockmarked face offers what may be humanity’s most familiar view of impact craters.
One of the easiest to spot is Tycho, the tight circle and bright, radiating splat are easy slightly off center on the lower-left side of the full moon. Closer views of the 53-mile (85 kilometer)-wide crater from orbiting spacecraft reveal a beautiful central peak, topped with an intriguing boulder that would fill about half of a typical city block.
5. Mars: Still Taking Hits
Mars has just enough atmosphere to ensure nail-biting spacecraft landings, but not enough to prevent regular hits from falling space rocks. This dark splat on the Martian south pole is less than a year old, having formed between July and September 2018. The two-toned blast pattern tells a geologic story. The larger, lighter-colored blast pattern could be the result of scouring by winds from the impact shockwave on ice. The darker-colored inner blast pattern is because the impactor penetrated the thin ice layer, blasting the dark sand underneath in all directions.
6. Ceres: What Lies Beneath
The bright spots in Ceres’ Occator crater intrigued the world from the moment the approaching Dawn spacecraft first photographed it in 2015. Closer inspection from orbit revealed the spots to be the most visible example of hundreds of bright, salty deposits that decorate the dwarf planet like a smattering of diamonds. The science behind these bright spots is even more compelling: they are mainly sodium carbonate and ammonium chloride that somehow made their way to the surface in a slushy brine from within or below the crust. Thanks to Dawn, scientists have a better sense of how these reflective areas formed and changed over time — processes indicative of an active, evolving world.
7. Comet Tempel 1: We Did It!
Scientists have long known we can learn a lot from impact craters — so, in 2005, they made one themselves and watched it happen.
On July 4, 2005, NASA’s Deep Impact spacecraft trained its instruments on an 816-pound (370-kilogram) copper impactor as it smashed into comet Tempel 1.
One of the more surprising findings: The comet has a loose, “fluffy” structure, held together by gravity and contains a surprising amount of organic compounds that are part of the basic building blocks of life.
8. Mimas: May the 4th Be With You
Few Star Wars fans — us included — can resist Obi Wan Kenobi's memorable line “That’s no moon…” when images of Saturn’s moon Mimas pop up on a screen. Despite its Death Star-like appearance, Mimas is most definitely a moon. Our Cassini spacecraft checked, a lot — and the superlaser-looking depression is simply an 81-mile (130-kilometer) wide crater named for the moon’s discoverer, William Herschel.
9. Europa: Say What?
The Welsh name of this crater on Jupiter’s ocean moon Europa looks like a tongue-twister, but it is easiest pronounced as “pool.” Pwyll is thought to be one of the youngest features we know of on Europa. The bright splat from the impact extends more than 600 miles (about 1,000 kilometers) around the crater, a fresh blanket over rugged, older terrain. “Fresh,” or young, is a relative term in geology; the crater and its rays are likely millions of years old.
10. Show Us Your Greatest Hits
Got a passion for Stickney, the dominant bowl-shaped crater on one end of Mars’ moon Phobos? Or a fondness for the sponge-like abundance of impacts on Saturn’s battered moon Hyperion (pictured)? There are countless craters to choose from. Share your favorites with us on Twitter, Instagram and Facebook.
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10 Things: How to Photograph a Meteor Shower
Taking photographs of a meteor shower can be an exercise in patience as meteors streak across the sky quickly and unannounced, but with these tips – and some good fortune – you might be rewarded with a great photo.
These tips are meant for a DSLR or mirrorless camera, but some point-and-shoot cameras with manual controls could be used as well.
1. The Photo Op: Perseids Meteors
The Perseids are dusty remnants of comet 109P/Swift-Tuttle.
Earth passes through the comet’s invisible, multi-billion mile trail of tiny debris each year around August, creating a meteor shower of so-called “shooting stars” as the particles are vaporized in our atmosphere.
Perseid meteors already are streaking across the sky. This year's shower peaks on a moonless summer night -from 4 pm on the 12th until 4 am on the 13th Eastern Daylight Time.
Read more on the Perseids ›
2. Get away from city lights and find a place with dark skies.
In this 30 second exposure, a meteor streaks across the sky in Spruce Knob, West Virginia, during the 2016 Perseids meteor shower. Credit: NASA/Bill Ingalls
Too much light and it will be hard for your eyes to see fainter meteors, plus your image will get flooded with the glow of light. Turning down the brightness of the camera’s LCD screen will help keep your eyes adjusted to the dark. The peak of the 2018 Perseid meteor shower occurs just after the new moon, meaning a thin crescent will set long before the best viewing hours, leaving hopeful sky watchers with a moonlight-free sky!
3. Use a tripod.
In this ten-second exposure, a meteor streaks across the sky above Washington, DC during the 2015 Perseids meteor shower, Credit: NASA/Joel Kowsky
Meteor photography requires long exposures, and even the steadiest of hands can’t hold a camera still enough for a clear shot. Heavier tripods help reduce shaking caused by wind and footsteps, but even a lightweight tripod will do. You can always place sandbags against the feet of the tripod to add weight and stability. If you don’t have a tripod, you might be able to prop your camera on or up against something around you, but be sure to secure your camera.
4. Use a wide-angle lens.
In this 30 second exposure taken with a circular fish-eye lens, a meteor streaks across the sky during the 2016 Perseids meteor shower as a photographer wipes moisture from the camera lens Friday, August 12, 2016 in Spruce Knob, West Virginia. Credit: NASA/Bill Ingalls
A wide-angle lens will capture more of the sky and give you a greater chance of capturing a meteor in your shot, while a zoom lens captures a smaller area of the sky. The odds of a meteor streaking past that small patch are lower.
5. Use a shutter release cable or the camera’s built-in timer.
Long exposures are not just for meteors. In this shot taken at Joshua Tree National Park, a hiker's headlamp leaves a trail of light along a twilight path. Credit: National Park Service / Hannah Schwalbe
A tripod does a great job of reducing most of the shaking your camera experiences, but even the act of pressing the shutter button can blur your extended exposure. Using the self-timer gives you several seconds for any shaking from pressing the shutter button to stop before the shutter is released. A shutter release cable (without a self-timer) eliminates the need to touch the camera at all. And if your camera has wifi capabilities, you might be able to activate the shutter from a mobile device.
6. Manually focus your lens.
In this 30 second exposure, a meteor streaks across the sky during the annual Perseids meteor shower Friday, August 12, 2016 in Spruce Knob, West Virginia. Credit: NASA/Bill Ingalls
At night, autofocus will struggle to find something on which to focus. Setting your focus to infinity will get you close, but chances are you’ll have to take some test images and do some fine tuning. With your camera on a tripod, take a test image lasting a few seconds, then use the camera’s screen to review the image. Zoom in to a star to see how sharp your focus is. If the stars look like fuzzy blobs, make tiny adjustments to the focus and take another test image.
Repeat until you are happy with the result.
If your camera has a zoomable electronic viewfinder or live view option, you might be able to zoom to a star and focus without having to take a test image.
7. Aim your camera.
The Perseids appear to radiate from the constellation Perseus, visible in the northern sky soon after sunset this time of year.
Even though we don’t know when or where a single meteor will appear, we do know the general area from which they’ll originate.
Meteor showers get their name based on the point in the sky from which they appear to radiate. In the case of the Perseids, during their peak, they appear to come from the direction of the constellation Perseus in the northern sky.
8. Calculate your exposure time.
In this 20-second exposure, a meteor lights up the sky over the top of a mountain ridge near Park City, Utah. Even though this image was captured during the annual Perseid meteor shower, this "shooting star" is probably not one of the Perseid meteors, which originate from material left behind by Comet Swift-Tuttle. Instead, it's likely one of the many bits of rock and dust that randomly fall into the atmosphere on any given night. Credit: NASA/Bill Dunford
As Earth rotates, the stars in the sky appear to move, and if your shutter is open long enough, you might capture some of that movement. If you want to avoid apparent star movement, you can follow the 500 Rule. Take 500 and divide it by the length in millimeters of your lens. The resulting number is the length of time in seconds that you can keep your shutter open before seeing star trails. For example, if you’re using a 20 mm lens, 25 seconds (500 divided by 20) is the longest you can set your exposure time before star trails start to show up in your images.
9. Experiment!
In this 30 second exposure photo, hikers find their way to the top of Spruce Knob in West Virginia to view the annual Perseids meteor shower, Friday, August 12, 2016. Credit: NASA/Bill Ingalls
Once you know the maximum exposure time, you can set your shutter priority to that length and let the camera calculate other settings for your first image. Depending on how the image turns out, you can manually adjust aperture (set it to a lower number if the image is too dark) and ISO (set it to a higher number if the image is too dark) to improve your next images. Changing only one setting at a time will give you a better understanding of how those changes affect your image.
10. Enjoy the show.
The crew of the International Space Station captured this Perseid meteor falling to Earth over China in 2011. Credit: NASA
With your camera settings adjusted, capturing that perfect photo is just a matter of time and luck. The highest rate of meteors visible per hour is in the hours after midnight and before dawn. Set up your camera next to a lounge chair or a blanket to witness the wonder of a meteor shower for yourself – and, with any luck, you’ll take home some envy-inducing shots, too!
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The Geminids Are Now Playing in a Sky Near You
The Geminids, which peak during mid-December each year, are considered to be one of the best and most reliable annual meteor showers.
This month, they're active from Dec. 4-17, and peak the evening of Dec. 13-14 for a full 24 hours, meaning more worldwide meteor watchers will get to enjoy the show.
Below are 10 things to know about this beautiful spectacle.
1. The forecast.
From our resident night sky expert, Jane Jones: If you can see Orion and Gemini in the sky, you'll see some Geminids. Expect to see about 60 meteors per hour before midnight on Dec. 13 and from midnight-3:30 a.m. on Dec. 14 from a dark sky. You'll see fewer meteors after moonrise at 3:30 a.m. local time. In the southern hemisphere, you won't see as many, perhaps 10-20 per hour, because the radiant—the point in the sky where the meteor shower appears to originate—never rises above the horizon.
2. Viewing tips.
Kids can join in on the fun as early as 9 or 10 p.m. You'll want to find an area well away from city or street lights. Come prepared for winter temperatures with a sleeping bag, blanket, or lawn chair. Lie flat on your back and look up, taking in as much of the sky as possible. After about 30 minutes in the dark, your eyes will adapt and you'll begin to see meteors. Be patient—the show will last until dawn, so you have plenty of time to catch a glimpse.
3. Late bloomer.
The Geminids weren't always such as a spectacular show. When they first began appearing in the mid-1800s, there were only 10-20 visible meteors per hour. Since then, the Geminids have grown to become one of the major showers of the year.
4. Remind me—where do meteor showers come from?
Meteors come from leftover comet particles and bits from asteroids. When these objects come around the Sun, they leave a dusty trail behind them. Every year, the Earth passes through these debris trails, which allows the bits to collide with our atmosphere, where they disintegrate to create fiery and colorful streaks in the sky.
5. That said...
While most meteor showers come from comets, the Geminids originate from an asteroid: 3200 Phaethon. Asteroid 3200 Phaethon takes 1.4 years to orbit the Sun once. It is possible that Phaethon is a "dead comet" or a new kind of object being discussed by astronomers called a "rock comet." Phaethon's comet-like, highly-elliptical orbit around the Sun supports this hypothesis. That said, scientists aren't too sure how to define Phaethon. When it passes by the Sun, it doesn't develop a cometary tail, and its spectra looks like a rocky asteroid. Also, the bits and pieces that break off to form the Geminid meteoroids are several times denser than cometary dust flakes.
6. Tell me more.
3200 Phaethon was discovered on Oct. 11, 1983 by the Infrared Astronomical Satellite. Because of its close approach to the Sun, Phaethon is named after the Greek mythological character who drove the Sun-god Helios' chariot. Phaethon is a small asteroid: its diameter measures only 3.17 miles (5.10 kilometers) across. And we have astronomer Fred Whipple to thank—he realized that Phaethon is the source for the Geminids.
7. A tale of twins.
The Geminids' radiant is the constellation Gemini, a.k.a. the "Twins." And, of course, the constellation of Gemini is also where we get the name for the shower: Geminids.
8. In case you didn't know.
The constellation for which a meteor shower is named only helps stargazers determine which shower they're viewing on a given night; the constellation is not the source of the meteors. Also, don't just look to the constellation of Gemini to view the Geminids—they're visible throughout the night sky. 9. And in case you miss the show.
There's a second meteor shower in December: the Ursids, radiating from Ursa Minor, the Little Dipper. If Dec. 22 and the morning of Dec. 23 are clear where you are, have a look at the Little Dipper's bowl—you might see about 10 meteors per hour. 10. Endless opportunities. There are so many sights to see in the sky. Use the Night Sky Network, the Solar System Ambassadors, and the Museum Alliance to look up local astronomy clubs, and join them for stargazing events in town, and under dark skies.
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What’s Up for December 2016?
What’s Up for December? Mars and Neptune above the crescent moon and a New Year’s Eve comet!
2016 ends with fireworks as three planets line up as if ejected from a Roman candle. Mercury, Venus and Mars are visible above the sunset horizon all month long.
As Venus climbs higher in the sky, it looks brighter and larger than it appeared last month.
On New Year’s Eve, Mars and Neptune appear very close to each other. Through telescopes, rusty red Mars and blue-green Neptune‘s colors contrast beautifully.
There are two meteor showers this month – the Geminds and the Ursids. The best time to see the reliable Geminids will be next year, when the full moon won’t be so bright and interfering. This year, however, we may luck out and see some of the brighter meteors on the evening of the 13th and the morning of the 14th.
The best time to view the Ursids, radiating from Ursa Minor, or the little Dipper, will be from midnight on the 21st until about 1 a.m. on the 22nd, before the moon rises. They may be active on the 23rd and 24th, too.
We haven’t had a good easy-to-see comet in quite a while, but beginning in December and through most of 2017 we will have several binocular and telescopic comets to view.
The first we’ll be able to see is Comet 45P/Honda-Mrkos-Pajdušáková, which will appear low on the western horizon on December 15th. On that date, the comet will pass the pretty globular cluster M75.
By the 21st, it will appear edge-on, sporting a bluish-green head and a thin, sharp view of the fan-shaped tail.
On New Years Eve, the comet and the crescent moon will rendezvous to say farewell to 2016. A “periodic” comet is a previously-identified comet that’s on a return visit. Periodic comet 45P returns to the inner solar system every 5.25 years, and that’s the one that will help us ring in the new year.
Watch the full What’s Up for December video:
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What’s Up for September 2016
We won’t have a solar eclipse until Aug. 21, 2017, but observers in central Africa will see an annular eclipse, where the moon covers most but not all of the sun, on Sept. 1. Observers always need to use safe solar eclipse glasses or filters on telescopes, binoculars and cameras.
Also this month, there are two minor meteor showers, both with about 5 swift and bright meteors per hour at their peak, which will be near dawn. The first is the Aurigid shower on Sept. 1. The new moon on the first means the sky will be nice and dark for the Aurigids.
The second shower is the Epsilon Perseids on Sept. 9. The first quarter moon sets on the 9th at midnight, just in time for the best viewing of the Perseids.
There are many nice pair-ups between the moon and planets this month. You can see the moon between Venus and Jupiter on Sept. 2, and above Venus on the 3rd, right after sunset low on the West-Southwest horizon. On the 15th the nearly full moon pairs up with Neptune, two weeks after its opposition, when the 8th planet is closest to Earth in its orbit around the sun.
Watch the full September “What’s Up” video for more:
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There’s Going to Be an Outburst!
Watch the Perseid Meteor Shower at Its Peak Tonight
The last time we had an outburst, that is a meteor shower with more meteors than usual, was in 2009. This year’s Perseid meteor shower is predicted to be just as spectacular starting tonight!
Plan to stay up late tonight or set your alarm clock for the wee morning hours to see this cosmic display of “shooting stars” light up the night sky. Known for it’s fast and bright meteors, tonight’s annual Perseid meteor shower is anticipated to be one of the best meteor viewing opportunities this year.
For stargazers experiencing cloudy or light-polluted skies, a live broadcast of the Perseid meteor shower will be available via Ustream overnight tonight and tomorrow, beginning at 10 p.m. EDT.
“Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke with NASA’s Meteoroid Environments Office in Huntsville, Alabama. “Under perfect conditions, rates could soar to 200 meteors per hour.”
Every Perseid meteor is a tiny piece of the comet Swift-Tuttle, which orbits the sun every 133 years. When Earth crosses paths with Swift-Tuttle’s debris, specks of comet-stuff hit Earth’s atmosphere and disintegrate in flashes of light. These meteors are called Perseids because they seem to fly out of the constellation Perseus.
Most years, Earth might graze the edge of Swift-Tuttle’s debris stream, where there’s less activity. Occasionally, though, Jupiter’s gravity tugs the huge network of dust trails closer, and Earth plows through closer to the middle, where there’s more material.
This is predicted be one of those years!
Learn more about the Perseids!
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What’s Up for August 2016
What’s up for August? How to spot Mercury, Venus, Mars, Jupiter and Saturn, as well as the and the annual Perseid meteor shower.
Here are some highlights in this month’s nighttime skies as picked by astronomer Jane Houston Jones from our Jet Propulsion Laboratory.
Spot Venus, Mercury and Jupiter and the moon low on the western horizon about 45 minutes after sunset from August 4 through 7. On August 11, look in the south-southwest sky for a second planetary dance as Mars and Saturn are high and easy to see and they are joined by the moon.
The famous and reliably active Perseid meteor shower peaks in the morning hours of August 12. The moon, which paired up so nicely with Mars and Saturn on the 11, is bright enough to blot out some of the meteors, but lucky for you it sets about 1 a.m. on the morning of the 12, just at the peak time for the best Perseid viewing.
But wait, there are more planets, dwarf planets and an asteroid visible this month! Uranus and Neptune and dwarf planet Ceres are visible before dawn in the southern sky. Uranus is visible through binoculars but Neptune and Ceres require a telescope.
Watch the full August “What’s Up” video for more:
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Five Fun Facts for the 2015 Geminid Meteor Shower
The Geminid meteor shower peaks this weekend starting on Sunday, Dec. 13. Here are a few fun facts:
Fact #1:
The Geminid meteor shower can be seen from both the Northern and Southern hemispheres. Because they are pieces of an asteroid, Geminid meteoroids can penetrate deeper into Earth’s atmosphere than most other meteor showers, creating beautiful long arcs viewable for 1-2 seconds.
Fact #2:
Geminids are pieces of debris from an object called 3200 Phaethon. It was long thought to be an asteroid, but is now classified as an extinct comet.
Phaethon’s eccentric orbit around the sun brings it well inside the orbit of Mercury every 1.4 years. Traveling this close to the sun blasts Phaethon with solar heat that may boil jets of dust into the Geminid stream. Of all the debris streams Earth passes through each year, the Geminid shower is the most massive. When we add up the amount of dust in this stream, it outweighs other streams by factors of 5 to 500.
Fact #3:
Because they are usually bright, many people say Geminid meteors show color. In addition to glowing white, they have been described as appearing yellow, green, or blue.
Geminid meteoroids hit earth's atmosphere traveling 78,000 mph or 35 km/s. That may sound fast, but it is actually somewhat slow compared to other meteor showers.
Fact #4:
Geminids are named because the meteors seem to radiate from the constellation of Gemini. The shower lasts a couple of weeks, with meteors typically seen Dec. 4-17, peaking near Dec 13-14.
Fact #5:
The Geminids started out as a relatively weak meteor shower when first discovered in the early 19th century. Over time, it has grown into the strongest annual shower, with theoretical rates above 120 meteors per hour.
Join In:
This Sunday, Dec. 13, our Marshall Space Flight Center in Huntsville, Alabama, will host a live tweet chat highlighting the 2015 Geminid meteor shower. This online, social event will occur 11 p.m. EST Dec. 13, until 3 a.m. EST on Dec. 14. To join the conversation and ask questions, use #askNASA or @NASA_Marshall.
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What are Perseid Meteors, and why should you be excited for them this year? Let us tell you!
The Perseid meteor shower is caused by debris from Comet Swift-Tuttle as it swings through the inner solar system and ejects a trail of dust and gravel along its orbit. When the Earth passes through the debris, specs of comet-stuff hit the atmosphere at 140,000 mph and disintegrate in flashes of light. Meteors from this comet are called Perseids because they seem to fly out of the constellation Perseus.
Last year, this meteor shower peaked during a bright “supermoon”, so visibility was reduced. Luckily, forecasters say the show could be especially awesome this year because the Moon is nearly new when the shower peaks on Aug. 12-13.
The best place to view the event is away from city lights around midnight. Under a clear, dark sky forecasters predict meteor rates as high as 100 per hour on peak night. So, get outside, look up and enjoy the show!
If your area has poor visibility on the peak night, we’ve got you covered! We’ll be hosting a live broadcast about the meteor shower from 10 p.m. EDT Wednesday, Aug. 12, to 2 a.m. Thursday, Aug. 13. In addition to footage from our live skycam, the program will highlight the science behind the Perseids, as well as our research related to meteors and comets. Tune in on NASA TV or our UStream Channel.