When a meteoroid enters the Earth’s atmosphere at a very high speed it heats up. This heating up produces a streak of light and is termed a meteor. When a meteor is bright enough, about the brightness of Venus or brighter, it becomes a fireball. Sometimes these fireballs explode in the atmosphere, becoming bolides. These bolides are bright enough to be seen even during the day.
Studying bolides as they pass through the atmosphere can help model larger asteroids, something of interest to the Planetary Defense Coordination Office (PDCO) which is run by NASA. These asteroids can be deadly if they are large enough, and learning how to predict their behavior is essential to protecting our planet from a devastating impact with long-term implications for the survival of many species on Earth.
When a meteor strike the Earth’s atmosphere, a magnificent (and potentially deadly) explosion is often the result. The term for this is “fireball” (or bolide), which is used to describe exceptionally bright meteor explosions that are bright enough to be seen over a very wide area. A well-known example of this is the Chelyabinsk meteor, a superbolide that exploded in the skies over a small Russian town in February of 2013.
On December 18th, 2018, another fireball appeared in the skies over Russia that exploded at an altitude of about 26 km (16 mi) above the Bering Sea. The resulting debris was observed by instruments aboard the NASA Terra Earth Observation System (EOS) satellite, which captured images of the remnants of the large meteor a few minutes after it exploded.