Ever Get the Feeling that Earth is Near the Center of a Target?
Posted by pwl on March 14, 2009
This image of our solar system’s asteroids sure freaks me out since it shows how precarious life on earth is in terms of the celestial game of billiards. Some say that the conditions are just right for life here on earth, and yes they are but it’s such a tiny pocket of life most of which exists in the thin layer of atmosphere or even thinner ocean layer. We exist in a bath tub of air and water that could get knocked around pretty darn good with any wayward space rock of sufficient size. Splat into earth and there goes life.
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt region is also termed the main belt to distinguish it from other concentrations of minor planets within the Solar System, such as the Kuiper belt and scattered disc. More than half the mass of the main belt is contained in the four largest objects: Ceres, 4 Vesta, 2 Pallas, and 10 Hygiea. All of these have mean diameters of more than 400 km, while Ceres, the main belt’s only dwarf planet, is about 950 km in diameter.
The remaining bodies range down to the size of a dust particle. The asteroid material is so thinly distributed that multiple unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, and these can form an asteroid family whose members have similar orbital characteristics and compositions. Collisions also produce a fine dust that forms a major component of the zodiacal light. Individual asteroids within the main belt are categorized by their spectra, with most falling into three basic groups: carbonaceous (C-type), silicate (S-type), and metal-rich (M-type).
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