Transcript ppt
Asteroids Lab 10 Asteroid Belt • Most asteroids are believed to be remnants of the protoplanetary disc which were not incorporated into planets during the solar system's formation • Some asteroids have moons • Vast majority of the asteroids are within the asteroid belt, with elliptical orbits between those of Mars and Jupiter, about 2.8 AU from Sun • Asteroids are rocky, metallic objects that orbit the Sun, too small to be considered planets. • Asteroids range in size from about 1000 km down to the size of pebbles • If total mass of all asteroids was gathered into a single object, the object would be less than 1,500 kilometers (932 miles) across -- less than half the diameter of our Moon • Asteroids that are on a collision course with Earth are called meteoroids DOOMSDAY ASTEROID • • • • First spotted June 19, 2004 in AZ Seen again at Xmas in Australia Is 1000 ft wide Probability of it hitting earth rose from 1:170 to 1:38 • Impact would come on Friday the 13th in April 2029 Asteroid 2004 MN4 • After recalculations, belief is Asteroid 2004 MN4 will miss Earth by 15,000-25,000 miles – which is one-tenth the distance to the moon • Asteroid 2004 MN4 is a "regional" hazard -- big enough to flatten Texas or a couple of European countries with an impact equivalent to 10,000 megatons of dynamite -- more than all the nuclear weapons in the world Really, really bad asteroid! • In 2029, the close encounter with Earth will increase the size of the orbit, and the object could get into a resonance with the Earth • Could get orbit matchups every five years or nine years, or something in between • In fact, 2004 MN4 could come close again in 2034, 2035, 2036, 2037, 2038 or later • Read all about it at http://impact.arc.nasa.gov/