Asteroids are usually referred to as being a solid rock from outer space whereas comets are usually a mixture of ice and rock and typically burn up before hitting the earth.In 1907 a large something from outer space destroyed thousands of acres of forest in Tunguska.Dinosaur bones, on the other hand, are millions of years old -- some fossils are billions of years old.To determine the ages of these specimens, scientists need an isotope with a very long half-life.
This rules out carbon dating for most aquatic organisms, because they often obtain at least some of their carbon from dissolved carbonate rock.
Scientist for the last hundred years have been searching for a crator or remnants of space rock.
Finally in 2008 scientist think they have found an impact site at the bottom of a nearby lake Cheko.
click here to see the profile of the bottom of the lake!
Whats at the bottom might be shattered rocks or impact melt or maybe a piece of meteorite.