Our solar system is only a small fraction of the seemingly endless universe. It contains many things such as asteroids, comets, meteors, stars, over 50 moons, nine planets, and the center of our whole solar system, the Sun. In every solar system in the universe, there is a main star that uses its gravitational pull to keep the objects in that solar system in their orbits. This main star also gives off light and energy for any life. But, as far as humans know, there is no other life out in the vast expanse of space.

Although the Sun is what makes up most of our solar system, there are also nine planets. Until the 18^th century, we only knew of six planets. These were Mercury, Venus, Mars, Jupiter, Saturn, and of course, Earth. It took humans 149 years (1781-1930) to find the last three planets in our solar system. These planets were Uranus, Neptune, and Pluto. Astronomers call the four planets closest to the Sun (Mercury, Venus, Earth, and Mars) terrestrial planets because they all have hard rocky surfaces. Jupiter, Saturn, Uranus, and Neptune are the gas giants of our solar system. We call these planets Jovian planets that have no solid surfaces. Astronomers are not sure, but they think that the Jovian planets have solid cores. These four planets also have rings that are made up of chunks of ice and pieces of rock. Beyond the terrestrial planets and the four Jovian planets lies Pluto. Pluto seems out of place with its tiny body. Many great astronomers think that Pluto is just a large piece of ice.

Most of our planets have moons. Earth has only one moon that is about one-fourth the size of its owner. Jupiter, one of the largest planets, has at least 17 moons. Saturn has at least 18 moons. Pluto, the smallest planet, has one moon named Charon.

We have had comets and asteroids in our solar system ever since it was formed. Comets and asteroids are rocky or iced pieces of rock. A comet and an asteroid are different from each other because a comet has more ice on it, and an asteroid is usually longer than a comet. A comet’s orbit gets very close to the Sun and then goes back into the outer part of our solar system. Asteroids have an orbit that usually keeps them far away from the sun. Most asteroids are found in the asteroid belt between the two planets, Mars and Jupiter. Meteors, bits of rock, can also be found in our solar system. We mostly find them in Earth’s atmosphere.

Planets

In the vast expanse of space lies the Milky Way galaxy, home of more than one billion stars and many solar systems, including ours. Our solar system is located billions of miles away from the center of the Milky Way. It contains nine planets- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and last but not least, Pluto. In this section on planets in "Space in The Spotlight," you will learn about almost everything a kid needs to know about the planets.

Comets, Meteors and Asteroids

Killer asteroids, glowing comets, showering meteors!  Of course they look great on T.V.   What are they really though, massive and destructible objects that fly around in space?  Remains of planets that tried to form millions of years ago?  Or could they just be some of the most interesting items in the solar system?  You make the call.    

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All pictures courtesy of NASA unless otherwise noted