Emerald Robinson: Hi! I am Emerald Robinson and in this What Is video, we're going to discuss the collision of two objects in outer space, knows as an Impact Event. An Impact Event refers to what happens when any two celestial objects hit each other. Most of the time though, we use the term to describe, what happens when a comet, meteor or asteroid hits the earth or the moon. Astronomers call this group of objects that calls impact events, Bolides. When Bolides enter the earth's atmosphere, they do so at high rise of speed between 25,160,000 miles per hour. Most bolides disintegrate burning up as they move through earth's atmosphere. If a bolide makes it through the atmosphere and strikes the earth, it does so with an enormous force, 1 equal to 1000 of tons of dynamite. This force causes a depression called an impact crater. Although impact events may seem to be the stuff of science fiction, bolides with diameter smaller than 13ft actually hit the earth about once a year. We just don't always hear about them, because so much of the earth surface is covered with uninhabited land or open ocean. Some impact events have had major consequences for the earth. One of the most well knows is the Cretaceous-Paleogene event which occurred about 65 million years ago. During this event, scientists think a meteor about 6 miles across shrug the earth on Mexico's Yucatan Peninsula forming the 110 mile wide chicxulub impact crater and cause an extinction of about 75% of animal and plant life including most of the dinosaurs.
While we don't know for sure, if there will be another major impact event. Scientists at NASA use a system called Sentry to monitor non-celestial objects and calculate the likelihood of every potential impact event.