Earth moves through the meteoroid stream of particles left from the passages of a comet. The stream comprises solid particles, known as meteoroids, ejected by the comet as its frozen gases evaporate under the heat of the Sun when it is close enough - typically closer than Jupiter's orbit. The Leonids are a fast moving stream which come close to or cross the path of the Earth and impact the Earth at 72 km/s.[1] Leonids in particular are well known for having bright meteors or fireballs which may be 9 mm across and have 85g of mass and punch into the atmosphere like a car hitting at 60 mph. An annual Leonid shower may deposit 12 or 13 tons of particles across the entire planet. Sometimes these trails of meteoroids cause meteor showers and sometimes meteor storms.