Tag Archives: Marshall Space Flight Center Meteoroid Environment Office

NASA Marshall Experts to Share Total Solar Eclipse In-person, on TV

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On Monday, Aug. 21, for the first time in almost 100 years, all of North America will be treated to an eclipse of the sun. Those in the path of totality, running from Oregon to South Carolina, will experience one of nature’s most awe-inspiring events — a total solar eclipse.

Scientists, researchers and experts from NASA’s Marshall Space Flight Center in Huntsville, Alabama, will mobilize to experience the eclipse and share it with others. They will join participants from across the agency for a multi-hour broadcast, titled Eclipse Across America: Through the Eyes of NASA, to offer unprecedented live video of the celestial event, along with coverage of activities in parks, libraries, stadiums, festivals and museums across the nation, and on social media.

“It’s going to be a spectacular event,” said Marshall Chief Scientist James Spann. “We’ll be sharing our research and work with people and letting them know how to safely view the eclipse, not only at the events in the path of totality, but also worldwide online and on NASA Television. Excited doesn’t begin to describe how our team feels right now. It truly will be breath-taking, and we can’t wait.”

Marshall experts will be located at two of the broadcast’s 15 locations — Hopkinsville, Kentucky, and Austin Peay State University in Clarksville, Tennessee.

Read more here..

Total Solar Eclipse: The Physics of Light

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By Kevin Matyi

The motion of the moon is what causes eclipses, but the dramatic change in sunlight is what makes them so impressive to observers. But what exactly is happening when the moon passes in front of the sun?

The moon is blocking the sun’s light from reaching Earth, but there is more to the situation than just that. Their relative distance to Earth is one of the most important factors.

The sun is about 400 times farther from Earth than the moon and has a diameter about 400 times larger than the moon. As a result, both the sun and moon (near perigee) appear to be the same size in the sky, allowing the moon to perfectly block out the sun and cast a shadow on Earth during a total eclipse.

The shadow we see while in the path of totality is called the umbra, and the shadow of the surrounding partial eclipse is a penumbra. The shadow from an annular eclipse (when the moon appears smaller than the sun during an eclipse, and so a ring of light is visible around it) is called an anteumbra.

The physics of how each type of shadow is formed is difficult to explain but easy to visualize, so before I tell you about them, here is a picture (technically a ray diagram) of what happens during an eclipse:

Each of the three types of solar eclipse are caused by the moon blocking light from different parts of the sun.

Each of the three types of solar eclipse are caused by the moon blocking light from different parts of the sun.
Credit: Wikimedia Cmglee

For a total eclipse, the moon has to block out all of the sun’s light. To put the moon in the best position, imagine that a person on Earth is standing under the exact middle of the moon, the centerline of a total solar eclipse.

In this case, light coming from the middle of the sun is clearly going to be blocked by the moon, since it is directly in the way and visible light cannot penetrate rock. The most difficult light to block will be coming from the top and bottom of the sun.

To figure out whether the light will be blocked, a bit of drawing can help. If the light is coming from the exact bottom of the sun and you are wondering if a person can see the light while under the exact center of the moon, draw a line between where the light starts and the person’s eyes.

Does the moon get in the way of the line? If yes, then the person is experiencing a total solar eclipse. None of the sun’s light can get past the moon, so the sun is fully blocked.

If the answer is no, but the person is still standing under the center of the moon, then they are in an annular eclipse. The moon is in the perfect position to block all of the sun’s light, but it still fails to do so. In this case, it will appear to be a large black circle with a ring of sunlight called an annulus around it.

A partial eclipse is the most difficult to explain, since it has the most variability. All but a sliver of the sun may be blocked, or the moon can barely cover any of the sun. In general though, a partial solar eclipse happens when the moon is not quite directly between the observer and sun, but is still in the way of some sunlight.

You can use the same process for determining whether a person is experiencing a total solar eclipse to figure out if they are in the penumbral shadow of the moon. A slight complication is that the moon is off center, so it matters more where the origin point of the light is.

If the person is standing a little north of the moon’s center, then the line from origin to person should start from the sun’s southernmost point, the bottom, since the northern light is less likely to be blocked due to the moon being a bit more to the south from the person’s perspective.

If any of the sun’s light is blocked by the moon, then the person is experiencing a partial solar eclipse. The limit of this blockage, where only the slightest amount of sunlight is blocked, is the edge of the penumbra shadow.

If the moon is not blocking any light, then the moon may be close to the sun but there is no eclipse happening on that spot of Earth.

Look Up! Perseid Meteor Shower Peaks Aug. 11-12

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Make plans now to stay up late or set the alarm early next week to see a cosmic display of “shooting stars” light up the night sky. Known for it’s fast and bright meteors, the annual Perseid meteor shower is anticipated to be one of the best potential meteor viewing opportunities this year.

The Perseids show up every year in August when Earth ventures through trails of debris left behind by an ancient comet. This year, Earth may be in for a closer encounter than usual with the comet trails that result in meteor shower, setting the stage for a spectacular display.

“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.”

An outburst is a meteor shower with more meteors than usual. The last Perseid outburst occurred in 2009.

How to Watch the Perseids

The best way to see the Perseids is to go outside between midnight and dawn on the morning of Aug. 12. Allow about 45 minutes for your eyes to adjust to the dark. Lie on your back and look straight up. Increased activity may also be seen on Aug. 12-13.

For stargazers experiencing cloudy or light-polluted skies, a live broadcast of the Perseid meteor shower will be available via Ustream overnight on Aug. 11-12 and Aug. 13-14, beginning at 10 p.m. EDT.

Read more about the Perseids here.

An outburst of Perseid meteors lights up the sky in August 2009 in this time-lapse image. Stargazers expect a similar outburst during next week’s Perseid meteor shower, which will be visible overnight on Aug. 11 and 12. Credits: NASA/JPL

An outburst of Perseid meteors lights up the sky in August 2009 in this time-lapse image. Stargazers expect a similar outburst during next week’s Perseid meteor shower, which will be visible overnight on Aug. 11 and 12.
Credits: NASA/JPL

Fireball Over Arizona

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For a few seconds early Thursday, night turned into day as an extremely bright fireball lit the pre-dawn sky over much of Arizona, blinding all-sky meteor cameras as far away as western New Mexico.

Based on the latest data, a small asteroid estimated at 5 feet (1-2 meters) in diameter – with a mass of a few tons and a kinetic energy of approximately half a kiloton – entered Earth’s atmosphere above Arizona just before 4 a.m. local (MST) time. NASA estimates that the asteroid was moving at about 40,200 miles per hour (64,700 kilometers per hour).

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Video obtained from the NASA meteor camera situated at the MMT Observatory on the site of the Fred Lawrence Whipple Observatory, located on Mount Hopkins, Arizona, in the Santa Rita Mountains.

Read more here.

Fireball Seen Over Tennessee and North Carolina

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We observed a fireball the morning of May 4 around 12:50am EDT, traveling southwest at about 77,000 mph over the Nantahala National Forest on the Tennessee/North Carolina state line. At its brightest point, it rivaled the full moon. According to Dr. Bill Cooke in NASA’s Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Ala. , “The fireball was bright enough to be seen through clouds, which is an attention getter. In Chickamauga, Ga., one would have thought it was a flash of lightning lighting up the clouds beneath.”

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Bright Fireball Detected by 6 NASA All Sky Cameras

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We have received numerous reports concerning a bright fireball that occurred over Georgia at 5:33:55 PM CST (6:33:55 PM EST). All 6 NASA all sky meteor cameras in the Southeast picked up the meteor at an altitude of 50 miles above the town of Georgia (SE of Atlanta). From its brightness, it is estimated that this piece of an asteroid weighed at least 150 pounds and was over 16 inches in  diameter. It entered the atmosphere at a steep angle and moved almost due south at a speed of 29,000 miles per hour. The NASA cameras tracked it to an altitude of 17 miles above the town of Locust Grove, where it had slowed to a speed of 9000 miles per hour, at which point the meteor ceased producing light by burning up. It is possible that fragments of this object survived to reach the ground as meteorites.

A more detailed analysis will be performed tomorrow and further details will follow if this analysis still indicates the possibility of a meteorite fall.

Ground track, still images from the cameras, and a movie from the NASA camera located in Cartersville, Georgia attached.

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Five Fun Facts for the 2015 Geminid Meteor Shower

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#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. Click the image to view a Geminid in action.

Marshall Space Flight Center will host a live Tweet Chat from 10 p.m. Dec. 13, until 2 a.m. on Dec. 14. Meteor experts Dr. Bill Cooke, Danielle Moser and Rhiannon Blaauw, all from NASA’s Meteoroid Environment Office, located at Marshall, will stay up late answering questions via Twitter. NASA followers interested in joining the online conversation can tweet their meteor questions to the Marshall Twitter account, @NASA_Marshall, or simply tag their tweets with #askNASA.

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#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. Click the image to view a Geminid in action.

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#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.

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#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. Click the image to view a Geminid in action.

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#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.

 

Fireball Seen in Early Evening Sky on Veterans Day

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On November 11 at 5:41:17 PM CST there was a fireball detected on two NASA cameras; one located at Marshall Space Flight Center in Huntsville, Alabama and the other in Tullahoma, TN.

Last evening’s fireball was just across the Tennessee/Arkansas border over the town of Jonesboro, Arkansas (NW of Memphis – see ground track image below). Speed was about 43,000 mph, and the object weighed around 10 pounds (6 inches in diameter).

The orbit, which extends well beyond Mars, indicates that the meteoroid is a piece of an asteroid.

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The Taurid Swarm is Upon Us!

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Every year from September-November, the Earth passes through a broad stream of debris left by Comet Encke.  The dust associated with the comet hits the Earth’s atmosphere at 65,000 mph and burns up, creating the Taurid meteor shower.  Most years the shower is weak, and only a few Taurid meteors can be seen each night.  Other years, the Taurids can put on a show.

This year, the Taurids may be more active than usual.

Bright Taurid fireballs may be more numerous this year, according to some scientists.  Known as the Taurid “swarm,” these bright meteors are created when the Earth runs into a group of pebble-sized fragments from the comet that then burn up in the atmosphere.

“The annual Taurid meteor shower is going on right now, and we are seeing steady activity in our meteor cameras,” said Bill Cooke, lead for the NASA Meteoroid Environments Office. “Individuals should not be surprised if they see a bright meteor or fireball over the next few nights.”

Taurid meteors can be seen any time the constellation Taurus is above the horizon during the months of September, October, and November. The best time to look for Taurids is after midnight, when Taurus is high in the sky, and when the sky is dark and clear, with no moonlight to mask the fainter meteors.  Given the behavior of past Taurid swarms, increased fireball activity may be seen during the last week of October and the first two weeks of November.

A bright Taurid fireball recorded by the NASA All Sky Fireball Network station in Tullahoma, Tennessee in 2014.

A bright Taurid fireball recorded by the NASA All Sky Fireball Network station in Tullahoma, Tennessee in 2014.

A bright Taurid fireball recorded by the NASA All Sky Fireball Network station in Cartersville, Georgia in 2012.

A bright Taurid fireball recorded by the NASA All Sky Fireball Network station in Cartersville, Georgia in 2012.

A bright Taurid fireball recorded by the NASA All Sky Fireball Network station in Cartersville, Georgia in 2013.  The bright orb is the Moon.

A bright Taurid fireball recorded by the NASA All Sky Fireball Network station in Cartersville, Georgia in 2013. The bright orb is the Moon.

Annual Orionid Meteor Shower Peaks This Week

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Orionid meteors appear every year around this time when Earth travels through an area of space littered with debris from Halley’s Comet. This year the peak will occur on the night of Wednesday, Oct. 21 into the morning of Thursday, Oct. 22.

“The Orionids will probably show weak activity this year,” says Bill Cooke of the NASA Meteoroid Environments Office . “Bits of comet dust hitting the atmosphere will probably give us about a dozen meteors per hour.”

The best time to look for Orionid meteors is just before sunrise on Thursday, October 22nd, when Earth encounters the densest part of Halley’s debris stream.

Observing is easy: Wake up a few hours before dawn, go outside and look up. No telescope is necessary to see Orionids shooting across the sky. Viewing conditions are favorable this year, as the light from the gibbous Moon should set by 2 a.m. EDT time, permitting good viewing just before dawn when the rates will be at their highest.

A live stream of the night sky from NASA’s Marshall Space Flight Center in Huntsville, Ala. will be available via Ustream beginning October 21, at 10 p.m. EDT. The live feed is an alternative for stargazers experiencing bad weather or light-polluted night skies. If the weather in Huntsville is clear, Orionids may be seen in the feed as early as 11:30 p.m. EDT, though the hours before dawn should show the most Orionid activity.

The display will be framed by some of the prettiest stars in the night sky. In addition to Orionids, you’ll see the Dog Star Sirius, bright winter constellations such as Orion, Gemini, and Taurus, and the planets Jupiter and Venus. Even if the shower is a dud, the rest of the sky is dynamite.

Set your alarm, brew some hot chocolate and enjoy the show!

An Orionid meteor recorded by the NASA All Sky Fireball Network station on top of Mt. Lemmon, Arizona on October 13, 2015 at 04:31 a.m. EDT.

An Orionid meteor recorded by the NASA All Sky Fireball Network station on top of Mt. Lemmon, Arizona on October 13, 2015 at 04:31 a.m. EDT.

An Orionid meteor recorded by the NASA All Sky Fireball Network station on top of Mt. Lemmon, Arizona on October 13, 2015 at 04:31 a.m. EDT.  Orionid meteors appear to come from the direction of the constellation Orion, circled in orange.

An Orionid meteor recorded by the NASA All Sky Fireball Network station on top of Mt. Lemmon, Arizona on October 13, 2015 at 04:31 a.m. EDT. Orionid meteors appear to come from the direction of the constellation Orion, circled in orange.


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