Asteroid Alert - RIT Scientists Comment on Meteor Explosion

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Space.com and other news sources reported this morning that a meteor explosion over Russia's Ural Mountains had upstaged the anticipated asteroid due to skim the Earth's surface at 2:25 p.m. ET today. Scientists at NASA and the European Space Agency, discount connection between the event and asteroid 2012 DA14 that will come within approximately 17,150 miles of the planet.

Scientists at Rochester Institute of Technology offer their comments on the surprise meteor explosion:

David Merritt, professor of physics:

It's unlikely, though not impossible, that the Russian meteor is related to 2012 DA14, the asteroid that's passing within the moon's orbit this afternoon. The two events are separated by more than 12 hours, which means that the asteroid and meteor were hundreds of thousands of miles apart-probably on different orbits around the Sun.

Events like these-the meteor, and the near-collision with the asteroid-underscore the need for NASA and other government organizations to put more effort into early detection of potentially hazardous asteroids. Asteroids can be deflected, but only if there is advance warning.

Michael Richmond, professor of physics and director of RIT's Observatory:

At this point, there is still too little quantitative information available for me to estimate the size or mass of the object which caused the sky show over Russia. Based on a statement by Don Yeomans, a NASA researcher who is an expert on these matters-but who also has little information at this point-the object may have been a few meters across; perhaps the size of a car or van.

Objects like this strike the Earth more frequently than one might imagine. A good paper on the subject is "The rate of small impacts on Earth" by Bland, P. A. & Artemieva, N. A., in the journal Meteoritics, vol. 41, Issue 4, p.607-631 (2006). The paper includes a graph which you can find at

This graph shows that objects with a size of a few meters, corresponding to a mass of about 10,000 - 100,000 kilograms, strike the Earth maybe 1-10 times each year. So, the show in Russia is not all that unusual.

But it seems unusual because it occurred over a city, so that thousands of people saw it, recorded it, and told others about it. Because it happened over a city, it also broke many windows. Most of the objects like this enter the atmosphere far from any civilization- over the oceans, or forests, or mountains.

This object certainly is unrelated to the asteroid 2012 DA14, which is zipping past the Earth today. That asteroid is coming from the south, whereas this Russian object appeared to be moving from the east to west. Moreover, the Russian object made its closest approach many hours before 2012 DA14 will. At the speeds with which these objects (and the Earth) are moving in their orbits, a separation of many hours corresponds to nearly a million kilometers in space. These arguments are made by astronomer Phil Plait on his blog.

In most cases like this Russian one, the object breaks up in mid-air and only small bits may reach the ground. I have seen comments stating that some fragments entered a frozen lake in Russia, and that some researchers will investigate the region tomorrow, but I wouldn't put much faith into the report yet. There are some cases in which scientists have managed to recover some of the material from a bright fireball, though, and thus we have learned something about the chemical makeup of some meteors.

Brian Koberlein, senior lecturer, School of Physics and Astronomy:

Just a couple of main points up front to get the sensationalism out of the way:

This is not the asteroid (2012 DA14) that makes a close approach later today.

It did not make a huge crater, as some videos floating around claim.

We are not being bombarded by a meteor shower.

Terminology:

Meteoroid: small chunk of rock (typically sand grain to a few meters in diameter), but not big enough to be an asteroid.

Meteor: The fireball a meteoroid makes as it is going through the atmosphere (shooting star)

Meteorite: any chunk of meteoroid that reaches the ground.

This was a meteor that occurred over Chelyabinsk, Russia. It is notable for two main reasons. First, it was quite large. If you've ever seen a shooting star, they tend to be short streaks across the night sky. Those are typically caused by sand-grain sized meteoroids. This was large enough to glow very bright. From the videos it looks like it briefly shone as bright as the sun. I'm not sure of the size. We'll have to triangulate the videos from different vantage points to get an idea of the size. Not tiny, but not huge. The second big factor is that it was caught on several dash cameras, so we have a lot of footage of the meteor.

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