February 15 was no average day for residents of the western Siberian city of Chelyabinsk and the surrounding areas. A meteor, hurtling across the sky in a ball of fire, exploded with what some experts estimated was the force of an atomic bomb. The explosion unleashed a shock wave that blasted out windows in the buildings below. Panic spread and more than 1,000 people were injured.
Marina Ivanova is a senior scientist in the Laboratory of Meteoritics at Moscow's Vernadsky Institute. In an interview with RFE/RL correspondent Richard Solash, she explains what happens when meteors crash into Earth's atmosphere and why this recent incident was such an "extraordinary event."
RFE/RL: What happens when a meteor falls towards Earth's surface? How common is it?
Marina Ivanova: Meteorites have been falling on Earth all throughout the planet's history. Many meteorites fall every day, but most of them are very, very small. Big ones have been rare, relatively, during human life. Most small parts of asteroids and comets, called "meteors," burn up in the atmosphere; but if they have a big mass and survive the frictional heating and strike the surface of the Earth, they become "meteorites."
These pieces of cosmic material are traveling much faster than the speed of sound and typically cause sizable sonic booms. A lot depends on the type of meteorite material and its trajectory and mass. In the Chelyabinsk case, the trajectory of the meteor was almost horizontal and the mass was probably big enough to cause such an explosion.
RFE/RL: What caused the shock waves that shattered the windows?
Ivanova: When the meteor enters the atmosphere it heats up very hot because of friction with the air. It can explode from the heat and pressure. In this case, the blast was big enough to form strong shock waves and damage so many windows. Usually, injuries of people around the area of a meteorite fall are very, very rare. In this case, I can say that it was a very extraordinary [event].
RFE/RL: How often does a meteor strike of this nature occur?
Ivanova: This type of event, in general, is very extraordinary -- probably [occurring] once per 30 or 40 years -- and it can happen anywhere, in any part of the world. The largest recorded explosion of a space object was the famous Tunguska event in 1908. That was 5,000 kilometers east of Chelyabinsk. It's very, very rare.
RFE/RL: What can you tell us about the specific characteristics of this meteor?
Ivanova: For the moment, now, it is difficult to say, because we haven't yet seen the real meteorite material after the explosion. If we get a piece of material that was found in this region we definitely can tell about its type. I heard that some fragments may have fallen in the Chebarkul Reservoir, around the lake, and also that a 6-meter-wide crater was found. But we still have not heard about material being found. If the material was a comet, made of ice and dust, for example, it could be completely evaporated by the explosion. But if the material was stone or iron, we definitely expect that pieces would be found and studied.
RFE/RL: The meteor was apparently not tracked ahead of time by scientists. Was it possible to have done so?
Ivanova: It's a difficult task to track cosmic bodies of this size -- for example, a few tons. It is much easier to watch large asteroids using telescopes and predict their movement. But to predict a collision with such a size meteorite traveling very fast in space or the accurate place of its fall, that's almost impossible now, unfortunately.
RFE/RL: What can scientists hope to learn from this meteor strike?
Ivanova: Any meteorite fall is important for scientific information -- for ballistics, physics, [and] cosmic chemistry. If material is found, it will tell us interesting things about its origins and history. Meteorites have records of the first processes that happened when the universe was born. I also think all scientists in all countries should try to develop capabilities to possibly predict such kinds of events to avoid any damage and injuries to people -- and, of course, to share all scientific information and experiences.
Editors' note: Ivanova's father-in-law, Kevin Klose, is acting president of RFE/RL.