Astronomy terms are used to describe the various phenomena in space. In this section you can learn what every astronomy term means and how it helps us to better understand the cosmos.


Minute, a unit for measuring both time and space. As a unit of time, a minute is 60 seconds, or 1/60 of an hour.

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  • Can a planet float on water?

    Can a planet float on water?

    Scientists announced the discovery of the largest known planet in the universe. TrES-4 has a density similar to balsa wood, and some say this gas giant could float on water. Learn why this planet is so puzzling and how planet hunters make amazing discoveries like these. See more »

  • Can scientists recreate the big bang?

    Can scientists recreate the big bang?

    Modern science allows us to break atoms down into tiny components. But can scientists use their mighty machines to recreate the foundation of the universe? See more »

  • Does space have a shape?

    Does space have a shape?

    Some scientists believe that space is infinite. But is it? If it isn't, what form does space take? Is it a dodecahedron or a triple torus? See more »

  • How Asteroids Work

    How Asteroids Work

    Eros is 21 miles long and 8 miles thick -- a mini planet! Explore the mission that landed on this asteroid after orbiting it for a year! See more »

  • How Black Holes Work

    How Black Holes Work

    A black hole occurs when a massive star dies -- its enormous mass implodes and becomes so heavy that it bends space. So how do astronomers detect something that they can't see? See more »

  • How Comets Work

    How Comets Work

    Comets are remarkable pieces of our universe's past, and they tell us a great deal about how the universe was formed. Learn about the long but rewarding process of discovering and analyzing comets. See more »

  • How Dark Matter Works

    How Dark Matter Works

    For decades, stargazing scientists have been facing their own darkness on the edge of town as they try to explain one of astronomy's greatest mysteries: dark matter. Have they been successful, or will the universe carry its secrets for a long time? See more »

  • How Deep Impact Works

    How Deep Impact Works

    How do scientists find details about the early days of our solar system? One way is to investigate comets. Find out how the Deep Impact spacecraft fired an impactor into Comet Tempel 1 to get some answers. See more »

  • How did the universe begin?

    How did the universe begin?

    You've heard of the big bang, of course, but do you have any idea as to what was happening during that massive flurry of activity billions of years ago? See more »

  • How Galaxies Work

    How Galaxies Work

    So much about galaxies remains a mystery. We know what they're made of and that we live in one (the Milky Way), but we're not sure how they form and evolve. See more »

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