This just in from Spaceweather.com:
"A small, newly-discovered asteroid named 2008 TC3 is approaching Earth and chances are good that it will hit. Steve Chesley of JPL [NASA's Jet Propulsion Laboratory] estimates that atmospheric entry will occur on Oct 7th at 0246 UTC over northern Sudan [Africa].
"Measuring only a few meters across, the space rock poses NO THREAT to people or structures on the ground, but it should create a spectacular fireball, releasing about a kiloton of energy as it disintegrates and explodes in the atmosphere. Odds are between 99.8 and 100 percent that the object will encounter Earth, according to calculations provided by Andrea Milani of the University of Pisa."
If the estimates of a 2:46 UTC entry are correct, that translates to 10:46 p.m. EDT tonight. Here's a link to the asteroid's 3-D orbit diagram. It may take some time to load. And here's a link to the circular for this asteroid from the Minor Planet Center of the Smithsonian Astrophysical Observatory in Cambridge, MA. And here's more from NASA.
Amazing. I can't remember ever seeing an alert like this before, and the NASA release says it's the first time one has ever been issued. It shows the search for "near-Earth asteroids" is beginning to provide us with real, useful warnings. A much bigger asteroid could explode over a populated area and do tremendous damage, like the Tunguska blast a century ago in Russia. It might also be misinterpreted as an enemy attack, triggering a retaliatory strike. This sort of warning could head off such a tragedy.
In this case, of course, there wasn't much warning. The asteroid was only discovered earlier today. But it will be fascinating to see how this plays out, and how accurate the prediction turns out to be. Stay tuned. In the meantime, here is an account of a similar event in 2003 near Chicago. And here's a pretty cool video of another over Australia.
Here's the full release from the Minor Planet Center:
BOULDER-SIZED ASTEROID WILL BURN UP IN EARTH'S ATMOSPHERE TONIGHT
A tiny asteroid discovered just hours ago at an Arizona observatory will enter Earth's atmosphere harmlessly at approximately 10:46 p.m. Eastern time tonight (2:46 a.m. Greenwich Mean Time). There is no danger to people or property since the asteroid will not reach the ground. It is between 3 and
15 feet (1-5 m) in diameter and will burn up in the upper atmosphere, well above aircraft heights. A brilliant fireball will be visible as a result.
"We want to stress that this object is not a threat," said Dr. Timothy Spahr, director of the International Astronomical Union's Minor Planet Center.
"We're excited since this is the first time we have issued a prediction that an object will enter Earth's atmosphere," Spahr added. Odds are between 99.8 and 100 percent that the object will encounter Earth, according to calculations provided by Andrea Milani of the University of Pisa.
When a meteoroid (small asteroid) enters the atmosphere, it compresses the air in front of it. That compression heats the air, which in turn heats the object, causing it to glow and vaporize. Once it starts to glow, the object is called a meteor.
"A typical meteor comes from an object the size of a grain of sand,"
explained Gareth Williams of the Minor Planet Center. "This meteor will be a real humdinger in comparison!"
The meteor is expected to be visible from eastern Africa as an extremely bright fireball traveling rapidly across the sky from northeast to southwest. The object is expected to enter the atmosphere over northern Sudan at a shallow angle.
"We're eager for observations from astronomers near the asteroid's approach path. We really hope that someone will manage to photograph it," said Williams.
The Minor Planet Center, which is located at the Harvard-Smithsonian Center for Astrophysics, serves as the worldwide clearinghouse for asteroid and comet observations. It collects, checks and disseminates observations and calculates orbits.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.