The Rocks

The main asteroid belt, found between the orbits of Mars and Jupiter is estimated to contain many millions of small rocks and about 1-2 million rocks of a diameter of 1 kilometer or greater. 26 known asteroids have a diameter of 200 kilometers or more. There are also rocks found in all other parts of the solar system but not in such great quantity.

asteroid belt

asteroid belt

Asteroid Introduction – []

Asteroids are rocky and metallic objects that orbit the Sun but are too small to be considered planets. They are known as minor planets. Asteroids range in size from Ceres, which has a diameter of about 1000 km, down to the size of pebbles. Sixteen asteroids have a diameter of 240 km or greater. They have been found inside Earth’s orbit to beyond Saturn’s orbit. Most, however, are contained within a main belt that exists between the orbits of Mars and Jupiter.

Asteroids – []

Asteroids are classified into a number of types according to their spectra (and hence their chemical composition) and albedo:

C-type, includes more than 75% of known asteroids: extremely dark (albedo 0.03); similar to carbonaceous chondrite meteorites; approximately the same chemical composition as the Sun minus hydrogen, helium and other volatiles;
S-type, 17%: relatively bright (albedo .10-.22); metallic nickel-iron mixed with iron- and magnesium-silicates;
M-type, most of the rest: bright (albedo .10-.18); pure nickel-iron.
There are also a dozen or so other rare types.

IAU: Minor Planet Center

An animation of the middle of the Solar System including the asteroid belt

PDS Asteroid/Dust Archive

This archive site provides access to PDS data on asteroids, dust, planetary satellites, meteorites, and selected other small solar system bodies and laboratory data.

…other posts on asteroids

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