Lesson 1 - Asteroid Alert! Vocabulary

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Reflectivity

Back

The property of reflecting light.

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Crater

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A large, bowl-shaped hole in the ground normally caused by explosions or impacts.

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Asteroid

Back

A rocky object that orbits the Sun.

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Near-Earth Object (NEO)

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An object in space, such as an asteroid, whose orbit will bring it close to the Earth.

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Absolute Brightness

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The term for how bright an object in space appears at a standard distance of 32.6 light-years or 10 parsecs.

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Transparency

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The property of allowing light to pass through so that objects behind can be distinctly seen.

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Opacity

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The measure of how much light is blocked by an object.

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Comet

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A celestial object made of ice and dust that, when close to the Sun, displays a visible atmosphere or coma and sometimes a tail.

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Planet

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A celestial body that orbits a star, is spherical in shape, and has cleared its orbit of other debris.

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Satellite

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An object that orbits a planet or a moon.