The Chelyabinsk Super Bolide: Part 1

Once or twice a century earth is struck by a fairly large asteroid. The leftover matter from the formation of the solar system is still floating around in space and sometimes they are pushed into a collision course with our planet. On February 15th, 2013 one such asteroid made its debut over the city of Chelyabinsk in Russia. This space invader was captured on many dashboard cameras, this entire event, from start to finish, was captured on video! The main mass landed in Lake Cebarkul. Divers bravely faced the icy waters to retrieve the largest mass they could find. The main mass is on display at the museum of South Ural History in Chelyabinsk Russia. The last recorded event of this magnitude occurred on June 30th, 1908 in Tunguska Russia. Ironically both were in Russia and both occurred in the morning, but Tunguska was much more devastating. A meteorite fall of this magnitude could cause devastation to the area it lands in, especially if it has a large population. The residents of Chelyabinsk are extremely lucky. Unfortunately, there were several people injured by the event.

The Chelyabinsk main mass, prior to entering earth's atmosphere, was about the size of a building or 20 meters in diameter. With a velocity of at least 27,000 miles per hour it hit the atmosphere at 9:20am local time. At that velocity even hitting an atmosphere is the equivalent of striking a brick wall, the asteroid begins to slow down but also quickly heat up from atmospheric friction and pressure. The surface of the space rock begins to melt and ablate, tiny droplets of melted material were cast off creating a dust cloud and a trail that formed in its’ wake. The intense heat that forms in front of the rock by compressed gases in the atmosphere reach up to 2,000 degrees Fahrenheit or more! This causes the surrounding gas and dust to incandesce, which is the fiery glow we see. In this state it is called a meteor. This is where it all gets interesting and we're only halfway through the fall.

The Chelyabinsk meteor had an apparent magnitude of -3, smaller numbers represent a brighter object, and we call these events super bolides. At the meteors' brightest point the space rock was at peak temperatures and because of the heat and pressure the rock exploded and broke into pieces about 15 miles up in the atmosphere. This also greatly reduced the velocity of the asteroid and the remaining pieces quickly cooled, no longer glowing, and continued their fall to the ground at about 200 miles per hour or less. This phase is called dark flight, what remains of the rock now harmlessly fall to earth where meteorite hunters can retrieve them. All of this happens in a matter of seconds! Most of the space rock was diminished by ablation and the explosion during the decent, about 97% or more of the initial mass of the asteroid is reduced to dust. Our atmosphere is an incredible shield, protecting us from large scale impacts such as these. But, the explosion still caused a lot of damage.