... Fireballs are sometimes followed by trails of light that persist for up to 30 minutes; some, called bolides, explode with a loud thunderous sound. ...
... at a velocity of 65 Km/s. As for the "small" impact asteroid, they assumed it had a mass of 5 x 1014 Kg traveling at a velocity of 20 Km/s. It is important to note that these two objects are possible bolides that hit the earth 65 million years ago ...