Space is a place of extremes. We have extremely large objects like stars and extremely small objects like dust particles in a stellar nebula. And then there are the objects that are more in the middle. A good example of these in between objects are comets, asteroids, and meteoroids. However, when these rocks come into contact with the Earth, their impact can definitely fall into the extreme category. Literally, space rocks.
There have been many famous impacts over the course of human history. One of the more recent examples was the recent fireball that exploded over Chelyabinsk, Russia. The main part of the meteor broke up a few miles above the city and the resulting shockwave blasted the glass from windows all around the city. The size of the meteor was estimated at about 20 meters across and a weight of about 12,000 metric tons. The amount of energy released when the meteor exploded was about 20-30 times the atomic bomb dropped on Hiroshima. Because the Chelyabinsk meteor broke apart before impact, the signature crater that defines a meteorite hitting the Earth was never formed. But there is a very famous meteorite crater found in Arizona.
The Arizona meteor crater was formed by an impact that occurred about 50,000 years ago. The crater is about .7 miles across, which puts the estimate for the size of the meteor at around 50 meters, more than double the Chelyabinsk meteor. Luckily no humans were around at the time of the impact or there would have been serious amounts of damage.
Fortunately, a large meteor impact has never happened in our lifetime, however scientists theorize that an impact large enough could have global consequences. In the Yucatan Peninsula, the Chicxulub Crater crater measures at an enormous 110 miles in diameter. The meteor that caused the impact was likely around 6 miles in diameter! The impact was so powerful that dust would have been thrown so high in the atmosphere that it would have spread to the far reaches of the Earth. The dust would have absorbed a good amount of sunlight from reaching the surface of the Earth, which would have caused a lowering of the Earth’s global temperature. If the temperature change was extreme enough, it is likely that many of the species on the planet would not have been be able to adapt to their new environment and would have died. We call this a mass extinction event. Scientist continue to studies meteors in hopes of better understanding and predicting impacts.