Fireballs
People tweeting about a green light "falling" from the sky Wednesday don't have the slightest clue.
But according to Geoff Chester, of the U.S. Naval Observatory, the celestial display was a rock, "probably something about the size of a basketball," entering the Earth's atmosphere at a speed in excess of 40 miles per second.
"Friction with the Earth's atmosphere causes the characteristic greenish glow," he says.
The light was seen by people up and down the Eastern Seaboard late Wednesday evening.
Chester says these "fireballs" occur almost daily, but aren't always reported because 70 percent of the planet's surface is covered in water and because most of the world's people reside near coast lines.
Obviously, since this light was visible to the East Coast of the U.S., plenty of people spotted it.
The space rock was about 2 feet in diameter and weighed more than 100 pounds. When it hit the Earth's atmosphere last week, it shone, briefly, 20 times brighter than the moon.
NASA's cameras captured the meteor as it zipped over the Southeast United States on Wednesday. In the video above, you can watch as it comes soaring through the sky and explodes in a flash of light.
The steady orb of light in the left of the frame is the moon.

The high temperatures of the meteorite impact 12,900 years ago produced mm-sized spherules of melted glass with the mullite and corundum crystal structure shown here.
Scientists have traced the geochemical signature of the BB-sized spherules that rained down back to their source, the 1.5-billion-year-old Quebecia terrane in northeastern Canada near the Gulf of Saint Lawrence.
At the time of the impact, the region was covered by a continental ice sheet, like Antarctica and Greenland are today.
"We have provided evidence for an impact on top of the ice sheet," said study co-author Mukul Sharma, a geochemist at Dartmouth College in Hanover, N.H. The results were published today (Sept. 2) in the journal Proceedings of the National Academy of Sciences.
Photos and videos of the object posted online have provoked a debate on Russian social networks, with various ideas offered for what it might be.
"I was sitting in my car. I did not start taking pictures immediately - first I did not pay attention. It was flying soundless," said one Internet user, who posted several photos of the event.
Initial Meteor Sighting Reports
25 August 2013 - Denise Totah, Lubbock, Texas 5:00 a.m.
5 maybe 10 seconds duration, travelling from west to east, my right to left. I was facing west. I thought it was a flash of lightning at first. I turned to look up and saw this big flash of light and it looked like it had 2 contrails at the end. I thought that maybe a plane had exploded, but there was no sound. It was a little brighter than the moon. It looked like 2 trails coming from it after it started disappearing. I didn't get a picture, I just know that the flash was bright enough to make me look up to the sky cause I thought it was lightning.Thomas Ashcraft - Heliotown - New Mexico writes,
"Did anyone catch a large fireball on Aug 25 2013 at 0954:50 UT in the west Texas- eastern New Mexico vicinity? (0354:50 am MDT / 0454:50 am CDT) I caught a flash behind clouds which might have come from over the horizon in which case this fireball would have been deeper into north central Texas. It should show on space fence radar for Texas observers. It made a 30 second radio reflection at 217 MHz and a two minute reflection on tv forward scatter frequencies."Sue Davis said...
I saw something go across the sky and catch on fire and slow down to almost a stop as it seemingly entered our atmosphere.. then it shot across sky and seemed to disappear... never seen anything like that. It was witnessed at 1:39 a.m. August 25, 2013 in Brazoria County Texas right outside of the town Angleton.
NASA's Meteoroid Environment Office has upgraded its estimates of a major fireball that exploded over the southeastern USA on August 28th. Lead researcher Bill Cooke says " the fireball reached a peak magnitude of -13, brighter than a Full Moon, and cast shadows on the ground. This indicates that the meteoroid had a mass of over 50 kg (110 lbs) and was about 40 cm (16 inches) in diameter. It hit the top of Earth's atmosphere traveling 23.7 km/s (53,000 mph)."
"As far as I know, this is the brightest event our network has observed in 5 years of operation," he continues. "There are reports of sonic booms reaching the ground, and data from 4 doppler radars indicate that some meteorites may have fallen along the fireball's ground track." (Note: The city in the ground track map is Cleveland, Tennessee, not Cleveland, Ohio.)
Using data from multiple cameras, Cooke has calculated a preliminary orbit for the meteoroid. The shape and dimensions of the orbit are similar those of a Jupiter-family comet. If meteorites are recovered from the Tennessee countryside, their chemical composition will tell researchers more about the origin of the fireball.

When the Chelyabinsk meteorite streaked across the sky in February, it caused quite a bit of a stir in Russia. The resulting shockwave from its impact shattered glass, injuring over a thousand people. Now, scientists have found out a little bit more about this meteorite. Fragment of Chelyabinsk meteorite, showing the fusion crust -- the result of a previous collision or near miss with another planetary body or with the sun.
The main body of the meteorite fell to the bottom of the Cherbarkul Lake near Celyabinsk. That's why in order to learn a little bit more about the meteorite, scientist examined fragments of the space rock. The fragments are composed of the same minerals as the main body of the meteorite, which means that the scientists could learn what they needed to know about the event.
So what did they find? It turned out that the meteorite had undergone an intensive melting process before being subjected to extremely high temperatures upon entering Earth's atmosphere. Based on the color and structure, the researchers were able to divide the fragments into three types: light, dark and intermediate. The lighter fragments were the ones that were most commonly found, but the dark fragments were found in increasing numbers along the meteorites trajectory, with the greatest number found close to where it hit Earth.
"Various aircraft over the north of the Canary Islands just reported a bright light, lasting 3 seconds, as if it was daytime," it tweeted.
It then added: "From the descriptions given by pilots it was probably a meteorite. Even so, protocols oblige that the military be informed" Witnesses described the phenomenon as "a white light coming down, with a long tail, falling."
Javier Licandro, of the Canaries Institute of Astrophysics (IAC), told the press that it was most likely a meteoroid of the kind that broke up in the atmosphere, rather than a meteorite which survives contact with the ground.
Nevertheless, he did not discount the possibility that it was the remains of an old satellite. Licandro said that he would check the data recorded by the observatories on La Palma and Tenerife to see if they had registered the phenomenon.
Twitter was soon full of people describing what they had seen.
@German_Herrera1 wrote: "I saw it from my house in La Laguna, a green light lasting three seconds. Impressive!"
There has so far been no official explanation given.
"F/A-18F Super Hornets were undertaking essential 'intercept' training in the 'western airspace' of RAAF Base Amberley, which incorporates the Toowoomba region," a Defence spokesperson says.
"Regrettably the training was louder than anticipated, and some residents experienced more aircraft noise than usually occurs, when Air Force uses the western airspace...our pilots and crews need experience in a range of environments. This includes day and night flying, high and low altitude flying (below 500 feet or 150 metres) and bombing and strafing practice."
The Airforce is investigating the "disruption".
Comment: Interesting, less than two months ago, another fireball exploded over the same region:
Bright meteor lights up Eastern coast of Australia
Comment: We have heard the bogus linking of meteors to rocket launches before:
Spectacular Russian rocket launch - more evidence of comet dust loading our atmosphere