RIT scientists comment on meteor explosion
Feb. 15, 2013
by Susan Gawlowicz
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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).
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.
• 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.
It is not related to the asteroid DA14. This arrived earlier, and has a different trajectory.
The meteoroid likely broke apart a few miles above the earth's surface. Reports of damage and injuries seem to be from the shockwave caused by the meteor. Injuries from glass shattered by the shockwave, not from the shockwave itself. Some pieces of the meteoroid may have reached the ground, but I haven't found any reliable reports yet.
Meteors occur in our atmosphere all the time. Even ones this size occur on a fairly regular basis, but not usually over populated areas where there are lots of video cameras.
Scientists do study meteorites that fall to earth. Some are material left over from the formation of the solar system, so their make-up helps us understand our solar system and how it formed. Some meteorites originate from other planets like Mars, which tells us about the geology of other planets.
Fun facts: On a typical day a meteoroid more than a foot across will strike our atmosphere. In a typical year a meteoroid 10 feet across strikes our atmosphere. So this particular meteoroid is not that uncommon, but it’s cool to have so much video of it.
Valerie Rapson, graduate student, astrophysical sciences and technology:
Small pieces of space rock enter Earth’s atmosphere all the time. Often, these rocks burn up completely, or disintegrate into tiny pieces in the upper atmosphere, and fall to Earth without being noticed. This meteor must have been fairly large, and my guess is that it entered Earth’s atmosphere at a fairly direct angle so that it didn’t spend a lot of time traveling through the thick atmosphere, which would have heated up and destroyed it sooner.
NASA and other space agencies do the best they can to detect Near Earth Objects, especially those on a collision course with Earth, and it’s not always easy to spot the small ones. They are cold and do not reflect a lot of light, so it’s hard to spot them with telescopes. Large objects that are a greater danger to Earth are a little easier to spot and their trajectories are well calculated, so we will know if one is on a collision course with Earth.
Scientists go out on meteorite expeditions to try and recover bits of meteorites to study in the lab to understand their composition. The composition of meteorites gives us information about what the solar nebula was made of (the gaseous cloud from which our sun and the planets formed from) and also help us understand how volatiles such as carbon and water ended up of Earth. I heard on the news that people are already looking for any small rocks that made it to the surface.
This probably has nothing to do with the upcoming asteroid flyby 2012 DA14. Large asteroids do not usually “bring” smaller rocks with them. There are almost 10,000 known Near Earth Objects, and tens of thousands of rocks in the asteroid belt. Occasionally, the orbits of some of these rocks are going to be disrupted and a few will come our way.
David Prinicpe, graduate student, astrophysical sciences and technology, adding to Rapson’s comments above:
The only thing that I would like to add is that each day 100 tons of space rock enter the atmosphere. That’s a lot of rock! Most burn up before they reach the ground, but this one must have been a bit bigger than normal.
Billy Vazquez, graduate student, astrophysical sciences and technology:
I have to echo the comments of Don Yeomans, head of NASA’s Near-Earth Object Program Office, about the bolide in space.com. It is not uncommon for Earth to be struck from material from space. Typically the size of these objects are small enough that they burnout entering our atmosphere. Some do reach the ground and they are sometimes recovered by scientists to study their composition. After all, its composition could tell us more about the chemistry of our solar system.
The nature of this explosion is due to the stresses the meteorite suffers as it enters our atmosphere as Yeomans explained on the linked article. A similar event occurred in Tunguska in 1908 but with a much larger object. The meteorite exploded as it entered our atmosphere and obliterated a forest area of hundreds of kilometers.
It is unlikely that this meteorite is related to asteroid 2012 DA14, as apparently its trajectory and distance do not justify a correlation.