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36 Cards in this Set
- Front
- Back
Revolution |
the movement of an object around another object. |
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rotate |
The spinning motion of a planet on its axis. |
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gravity |
The attractive force between objects; the force that moves objects downhill. |
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geocentric |
Term describing a model of the universe in which Earth is at the center of the revolving planets and stars. |
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heliocentric |
Term describing a model of the solar system in which Earth and the other planets revolve around the sun. |
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ellipse |
An oval shape, which may be elongated or nearly circular; the shape of the planets’ orbits. |
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solar system |
The system consisting of the sun and the planets and other objects that revolve around it. |
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astronomical unit |
A unit of distance equal to the average distance between Earth and the sun, about 150 million kilometers. |
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planet |
An object that orbits a star, is large enough to have become rounded by its own gravity, and has cleared the area of its orbit. |
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dwarf planet |
An object that orbits the sun and is spherical, but has not cleared the area of its orbit. |
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planetesimal |
One of the small asteroid-like bodies that formed the building blocks of the planets. |
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core |
The central region of the sun, where nuclear fusion takes place. |
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nuclear fusion |
The process in which two atomic nuclei combine to form a larger nucleus, forming a heavier element and releasing huge amounts of energy; the process by which energy is produced in stars. |
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radiation zone |
A region of very tightly packed gas in the sun’s interior where energy is transferred mainly in the form of electromagnetic radiation. |
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convection zone |
The outermost layer of the sun’s interior. |
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photosphere |
The inner layer of the sun’s atmosphere that gives off its visible light; the sun’s surface. |
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chromosphere |
The middle layer of the sun’s atmosphere. |
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corona |
The outer layer of the sun’s atmosphere. |
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solar wind |
A stream of electrically charged particles that emanate from the sun’s corona. |
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sunspot |
A dark area of gas on the sun’s surface that is cooler than surrounding gases. |
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prominence |
A huge, reddish loop of gas that protrudes from the sun’s surface, linking parts of sunspot regions. |
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solar flare |
An eruption of gas from the sun’s surface that occurs when the loops in sunspot regions suddenly connect. |
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terrestrial planet |
The name often given to the four inner planets: Mercury, Venus, Earth, and Mars. |
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greenhouse effect |
The trapping of heat near a planet’s surface by certain gases in the planet’s atmosphere. |
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gas giant |
The name often given to the outer planets: Jupiter, Saturn, Uranus, and Neptune. |
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ring |
A thin disk of small ice and rock particles surrounding a planet. |
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asteroid belt |
The region of the solar system between the orbits of Mars and Jupiter, where many asteroids are found. |
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kuiper belt |
A region that stretches from beyond the orbit of Neptune to about 100 times Earth’s distance from the sun. |
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oort cloud |
A spherical region of comets that surrounds the solar system. |
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comet |
A loose collection of ice and dust that orbits the sun, typically in a long, narrow orbit. |
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coma |
The fuzzy outer layer of a comet. |
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nucleus |
The solid inner core of a comet. |
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asteroid |
One of the rocky objects revolving around the sun that are too small and numerous to be considered planets. |
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meteoroid |
A chunk of rock or dust in space, generally smaller than an asteroid. |
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meteor |
A streak of light in the sky produced by the burning of a meteoroid in Earth’s atmosphere. |
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meteorite |
A meteoroid that passes through the atmosphere and hits Earth’s surface. |