alien Beings thought to live somewhere else out in space are called aliens. No one is sure if there is any other life in the universe, other than here on Earth. Another name for an alien is an extraterrestrial.
asteroid An asteroid is a small object similar in several ways to a planet. Many asteroids are made of rock and orbit the sun.
astrology A belief that stars and other objects in space can be used to predict future happenings or events. People who are born under certain signs are expected to have certain characteristics and qualities.
astronaut Explorers who travel out into space are known as astronauts. Some astronauts have become famous for taking the first steps in space or being the first woman or man to leave the Earth's atmosphere.
astronomy The study of all things in space. The people who watch the skies for new stars or planets or changes in the ones that have already been discovered are called astronomers. Astronomy is a type of science.
The gases contained around an object in space are called its
aurora One of nature's most spectacular light shows is called an aurora. These light shows take place close to the Northern and Southern Poles as solar particles collide with the earth's magnetic fields.
axis Like a top, each planet has a center line known as an axis that it revolves around. Earth's axis would run from its North Pole straight through to its South Pole.
comet A comet is an object that appears to have a glowing tail as it travels through space. One famous comet is Halley's comet, known for its timely return trips.
constellation A group of stars that together form an image in the sky. One constellation that is well known is Orion.
dwarf planet A planet that is smaller in size than the other planets it is being compared to. Pluto is considered a dwarf planet because it is so much smaller than the other planets in our solar system.
eclipse When an object in space blocks the light of another object or prevents it from being in view, it is called an eclipse. Two common eclipses are solar and lunar.
galaxy A large group of stars out in space. There are numerous galaxies in the universe. Galaxies can come in different shapes and sizes. The galaxy we live in is a spiral galaxy.
gravity The force that pulls things toward the earth. There is also a gravitational force in many other areas throughout the universe that seems to hold things together.
lunar A word that describes something that has to do with the moon. There are lunar calendars and lunar missions. If people lived on the moon it would be a lunar colony.
magnitude The amount of light a star emits or gives off is called its magnitude. Astronomers measure the magnitude of the stars out in the universe by using a number system.
meteorite The objects that fall from space onto the earth are called meteorites. When they start to burn in the sky, they are sometimes called falling stars.
meteorology The study of the Earth's atmosphere, usually involving activities within it such as the weather. Someone who studies meteorology is called a meteorologist.
Milky Way The spiral galaxy that appears in our sky, like a faint trail of spilled milk, is called the Milky Way. The Milky Way is made up of billions of stars.
myth A traditional story that is usually based on beliefs from religion or history. Myths have been told for years along with similar stories like tall tales, fables, and fairy tales.
nebula Nebulae can be both light and dark, depending on whether a star is shining on the nebula's dust or whether the nebula's dust is blocking the light from the star that is behind it.
Oort cloud A type of cloud that encircles our solar system. This cloud is believed to be the birthplace of some of the icy comets that can be found traveling through our solar system.
phase When something changes or develops, it goes through phases or stages. Each month the moon goes through a cycle of phases from a new moon to a full moon and back again. A crescent moon is one of the phases in the moon's cycle.
planetarium A special building designed to display all the wonders of the solar system and outer space to an audience.
Polaris The name given to the earth's pole star. You can find Polaris by looking for a bright star in the northern sky. It is part of a constellation we call the Little Dipper.
reflecting Normally, people are thinking of water or mirrors when they think about something reflecting an image or light. Even though the moon has no light source of its own, it shines in the sky because the sun's light is reflecting off of the moon's surface.
satellite A satellite can be a manmade object or something created in space that orbits planets such as Earth. Manmade satellites are used to send information from place to place or keep track of the weather.
science fiction When a story is made up or not true it is considered fiction. Science fiction is a blend of scientific information and fiction. Many stories and movies about space are considered science fiction.
solar system Our solar system consists of eight planets, one dwarf planet, the sun, and all of the other items that orbit around it. Our solar system is just one of many in the universe.
spectrum Scientists and astronomers use a spectroscope to see the breakdown or separation of light into a spectrum, the same colors created by light shining through a prism.
telescope A telescope is a tool that was invented to help people see things that are far away in the distance. Astronomers use telescopes to see planets and stars millions of miles out in space.
time warp Some scientists wonder if there are places in space where time is distorted or warped. One place they believe a time warp may exist is in or around a black hole. Because no one has ever been there they can only guess what might happen.
universe Everything around us as far as the eye can see. It contains stars, galaxies, planets, space, and us. Some people think there are other universes that go on beyond the one where we live.