- Planets are globe-shaped space objects that orbit a star.
- Planets begin life at the same time as their star, from left over clouds of gas and dust.
- Planets are never more than Twenty Percent of the size of a star. If they were bigger, they would have become stars.
- Some planets, called terrestrial planets, have a surface of solid rock. Others, called gas planets have a surface of liquid or airy gas.
- The solar system has nine planets including Pluto. But Pluto may be an escaped moon or an asteroid, not a planet.
- Giant planets have now been detected orbiting stars other than the sun. These are called extra-solar planets.
- Extra-solar planets are too far away to see, but can be detected because they make their star wobble.
- One extra-solar planet has now been photographed.
- Among the nine stars so far known to have planets are 47 Ursae Majoris, 51 Pegasi and 70 Virginis.
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