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Astronomy Facts for Kids

The "National Audubon Society Field Guide to the Night Sky" says that when a person looks out into the sky at night, she will see just a small part of what exists in space. Our earth is part of a group of other worlds called planets that orbit the sun, and the sun is just one of countless stars that exist. These stars are incredible distances away from us. The science known as astronomy is the study of space and these objects.

Inner and Outer Planets
- The planets that astronomers call the inner planets are Mercury, Venus, Earth and Mars. The inner planets are very different from the outer planets, which are the giant frozen worlds of Jupiter, Saturn, Uranus and Neptune. Pluto, formerly one of the outer planets, has a classification now as a dwarf planet and is not nearly the size of the other four outer planets. The inner planets, those that orbit closest to the sun, have very few moons if any and are small when compared to the outer planets. The inner worlds are made for the most part of rock. The outer planets have a large number of moons circling them and are so big that you could put 60 planets the size of Earth into Neptune, the smallest of them. These four planets are not like Earth at all; different types of gases make up most of these planets, and you would not survive breathing their deadly atmospheres.
Light Years
- Astronomy deals with distances that are so large that using a measurement as small as a mile becomes a problem. For example, the Earth, on average, is 93 million miles from the sun. As far at that seems, it is not even close to how far the Earth is from the next nearest star. Astronomers use a unit of measurement called a light year to gauge the distances to objects outside the solar system. A light year is the distance that light would travel in one year through space, going at its speed of about 186,000 miles every second. This distance equals approximately 5,880,000,000,000 miles. The closest star other than the sun is Proxima Centuri, which is about 4.2 light years away. When you look at this star, you see the light that started heading toward your eye 4.2 years ago; it took that long to reach Earth.
Constellations
- The stars in the night sky seemed to form patterns when looked upon by the ancient civilizations of Earth, and these peoples gave these patterns names. These star patterns are the constellations, which to the humans of long ago represented different kinds of animals, as well as some of their heroes and objects they used every day. There are 88 constellations. Some are very bright and easy to recognize, while others are hard to make out. Among the best-known constellations are Orion the Hunter and Ursa Major, the Great Bear. Orion has many bright stars within it, and Ursa Major contains what astronomers call an asterism, a grouping of stars within a constellation that form familiar shapes. The asterism within Ursa Major is the Big Dipper, seven stars that look like a water ladle.

Astronomy