Details Title: Astronomy Vocabulary Description: The Cosmic Perspective Total Flash Cards: 23 Created: 08/23/2009 10:33:13		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term Asteroid Definition A relatively small and rocky object that orbits a star; part of a category known as 'small solar system bodies'. Term Astronomical unit (AU) Definition The average distance (semimajor axis) of the Earth from the Sun, which is about 150 million km. Term Axis tilt Definition The amount by which a planet's axis is tilted with respect to a line perpendicular to the ecliptic planev Term Big bang Definition The name given to the event thought to mark the birth of the universe. Term Comet Definition A relatively small, icy object that orbits a star. Part of the category known as 'small solar system bodies'. Term Ecliptic plane Definition The plane of the Earth's orbit around the Sun. Term Expansion Definition The idea that the space between galaxies or clusters of galaxies is growing with time. Term Galaxy Definition A huge collection of anywhere from a few hundred million to more than a trillion stars, all bound together by gravity. Term Galaxy clusters Definition A collection of a few dozen or more galaxies bound together by gravity; smaller collections are called groups. Term Light year Definition The distance that light can travel in 1 year. Term Local group Definition The group of about 40 galaxies to which the Milky Way galaxy belongs Term Milky Way Definition Used both as the name of our galaxy and to refer to the band of light we see in the sky when we look into the plane of the Milky Way galaxy. Term Moon or satellite Definition An object that orbits a planet. Term Nuclear fusion Definition The process in which 2 (or more) smaller nuclei slam together and make one larger nucleus. Term Observable universe Definition The portion of the entire universe that, at least in principle, can be seen from Earth. Term Planet Definition A moderately large object that orbits a star and shines primarily by reflecting light from its star 1. Orbits a star (but is not star nor moon) 2. Massive enough to have a nearly round shape 3. Cleared the area around its orbit Term O Definition Term Orbit (revolution) Definition The orbital motion of one object around another. Term Rotation Definition The spinning of an object around its axis Term Solar system or Star system Definition Consists of a star (sometimes more than one star) and all the objects that orbit it. Term Star Definition A large, glowing ball of gas that generates energy through nuclear fusion in its core. Term Supercluster Definition Clusters of cluster of galaxies, groups of galaxies and individual galaxies. The largest known structures in the universe. Term Universe Definition The sum total of all matter and energy.