Planets
Planets form from the leftover bits and pieces of the interstellar cloud that gave rise to a star. It is theorized that planet formation is not unusual, but detecting planets around other stars is difficult. Only now are we beginning to discover the presence of planets around other stars. A star's formation may still yield more gas and dust. These leftovers clump together. Dust grains collide and stick together. More and more dust grains collide until they became larger bodies, which then collide with other larger bodies. Our own Solar System was formed this way millions of years ago. The young Sun vaporized many volatile materials, such as water, nearby. This left only metals and rocky material, giving rise to the solid inner planets of Mercury, Venus, Earth, and Mars. Further away from the sun, ice and gas still existed and the planets that formed away from the Sun are mostly gaseous giants. These planets are Jupiter, Saturn, Uranus, and Neptune. Pluto, the furthest planet from the sun, is solid ice and rock. Professional web hosting with gigabytes of disk space Because planets do not give off light of their own, they are difficult to detect. Astronomers focus on one star and try to detect if it "wobbles." A star wobbles because some object, usually a planet, is exerting a gravitational pull of its own on the star. As the star rotates and the planet revolves around the star, the star is pulled toward the planet and thus appears to wobble. Astronomers can venture a guess at the size of the planet by observing how much the star wobbles. Though these newer planets are further away, people cannot help but wonder if they could support life as Earth does. For more information on planets, consult the following links:
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