Chelyabinsk meteor shined brighter than the sun

Why was your article chosen for publication in Science?

We submitted the article in late June, after gathering and analyzing all observations available at that time. In particular, we had processed official reports on the destructions [caused by the meteor's atmospheric fly past] and information collected in the course of our own expedition.

Never before had this information been published. We had also built a model of the meteor's shock wave and compared it with the effects on the ground.

Did you learn anything new about the meteor?

We estimated its energy based on a variety of data. For infrasound observations, we were using our own station, as well as stations that were the closest to the area. Our infrasound measurements put the blast energy at 500 kilotons.

We also estimated the energy based on the data obtained by United States geostationary military satellites, which are normally used to monitor missile launches and nuclear tests. As a by-product, they register optical atmospheric events caused by meteor re-entries. Based on this information, we appraised the Chelyabinsk meteor's kinetic energy at 590 kilotons.

Our other estimate of the meteor's initial kinetic energy is based on measurements of the area on the ground where window glazing was damaged by the blast. Each of these methods is imprecise by itself, but they all are independent, which is important.

You visited 50 settlements [along the ground footprint of the meteor's flight path]. What exactly were you looking for?

It was a small expedition organized by our institute and by the Russian Academy of Sciences' Institute of Astronomy. Our aim was to collect information while the trail was still hot. We were gathering eyewitness accounts and were able to see for ourselves what the broken window glass looked like. We found that the ground damage footprint stretched 90 km (56 miles) across to the meteor's trajectory and had the shape of a butterfly.

Your article says that the blast damaged a monument to [Russian poet Alexander] Pushkin.

Yes, a Pushkin statue in a Yemanzhelinsk library developed cracks because of the blast wave.

What were the meteor's parameters?

Out of hundreds of available video recordings, we selected around a dozen and aligned the images with the astronomical reference system. This allowed us to determine the meteor's trajectory, entry angle, and speed. It was traveling at 19 km (11.8 miles) per second, measured 18 meters to 20 meters (59 feet by 65.6 feet) across, and weighed 1.3*10⁷ kg.

What kind of meteor was it?

It was a typical LL-type chondrite. Chondrites account for the lion's share of all meteors entering the Earth's atmosphere. They can be subdivided in three types by their content of iron; the Chelyabinsk meteor belongs to the category with the lowest iron content. However, it can still get registered with a metal detector, attract magnets, and rust.

Is there anything about the meteor that remains unclear to scientists?

All the principal questions have been answered at least to some extent. It is widely held that, as a rule, only about 10 percent of a meteor's total weight reaches the surface of the Earth. In our case the figure was under 1 percent. Therefore, we still don't know what damage objects sustain when they enter the Earth's atmosphere.

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