Origin and Present-Day Location of Asteroids

• Location:

  • Most are located in a region between Mars and Jupiter in an area where Jupiter would have kept the solar nebula "stirred up" and prevented any large bodies to form.

  • There are two groups of asteroids sharing Jupiter's orbit--one group on either side, at roughly 60 degrees Jupiter-Sun-asteroids angle. These groups are called the Trojan asteroids.

  • There are asteroids also located close to Earth's orbit (see Potentially Hazardous Asteroids and Near Earth Asteroids below).
• Evolution: all asteroids probably started out made of primitive materials. The larger asteroids generated enough internal heat from radioactive decay to melt (at least partially) and differentiated. Generally bodies larger than about 500 km are needed in order to "trap" the heat generated so that melting can occur. If the body is too small, it cools way too fast and no differentiation can take place. There were numerous collisions that broke larger asteroids into smaller pieces. So, irregular asteroids can occur for a couple of reasons: never differentiated or broken apart from a larger body.

Potentially Hazardous Asteroids

Near-Earth Objects

Destination: Earth! images. Some paintings, some real. See expecially the animation at the bottom of the page (mpeg format) showing the Peekskill meteorite (over 12 kilograms, or over 25 lbs) as it streaks through the atmosphere. This meteorite went through the trunk of a car in New York. The owner of the car (a Malibu coupe) eventually sold the meteorite for around $60,000. The car has gone on a world-wide tour. If you'd like to hire it for a show, see The Peekskill Meteorite Car.

HST Observations

Fly-bys and Landings

Galileo Spacecraft

Gaspra: images and information from JPL/NASA

Ida and Dactyl: images and infromation from JPL/NASA

NEAR Shoemaker

Mathilde: information and images from NPL/NASA

Eros

• Discovery is NEAR

• Check out the following linked from the home page:

  • Orbit

  • Landing Spot

  • Boulderado

  • Approach of the spacecraft

  • Spectrum from the surface

  • Rotation of Eros

Meteorite `Seeds' clue to origins of life on Earth article from the electronic Telegraph (UK), 5 April 2001.