We do not yet know for sure the size of meteor. It could be a rock weighing a few hundred kilograms, but we only expect a small part of this body to have reached the ground, our preliminary analysis suggests that it entered Earth's atmosphere at a speed of about 15 km/s( 9.3 miles per second) and it fragmented in a series of bright flashes between 35 and 25 km( 22 and 15.5 miles) above ground.