Meteorites

Meteors, asteroids, and other space debris hitting the Earth are actually a pretty common occurrence. However, thanks to our nice and think atmosphere, extremely large pieces of these extraterrestrial chunks of rock usually do not make it to the Earth's surface to cause damage. However, Earth did not always have an atmosphere for the rock to burn up in before making it to the land.

Much like volcanoes, meteorite impacts can severely alter the climate and cause big changes in Earth's species, including mass extinctions. In fact, a very large meteor impact near the Yucatan Peninsula in Mexico is thought to be the cause of the mass extinction that wiped out the dinosaurs at the end of the Mesozoic Era (66 MA). These impacts can also release ash and dust into the atmosphere and cause large changes in the the amount of sunlight that reaches the Earth. Not only does that affect global temperatures, but a prolonged period of no sunlight can affect the energy getting to the plants that can undergo photosynthesis. Without energy production by the plants, animals would run out of energy to eat and keep themselves alive.

50.000 years ago, a huge iron-nickel meteorite, hurtling at about 40.000 miles per hour, struck the rocky plain of Northern Arizona with an explosive force greater than 20 million tons of TNT. The meteorite estimated to have been about 150 feet across and weighing several hundred thousand tons, in less than a few seconds, left a crater 700 feet deep and over 4000 feet across. The object causing the impact looks to have been an asteroid.