Astronomy and Solar System Concepts

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asteroid

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a small, rocky object that orbits the sun (as small as a pebble to as large as mountains). Most orbit between Mars and Jupiter.

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astronomical unit

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a unit for measuring distances in our solar system that is the average orbital radius of Earth from the Sun.

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atmosphere

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The layers of gases that surround some planets that protect the planet from meteor strikes, radiation, and contribute to global average temperatures.

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chromosphere

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The middle layer of the Sun's atmosphere that has a reddish-orange coloration.

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comet

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A small, rocky, and icy object that orbits the sun that are held loosely together and have long elliptical orbits. When they approach the Sun they develop a large tail as ice becomes a gas when it heats up.

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convective zone

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The layer of the Sun that moves energy in the form of fluids rising when they are warmer and sinking when they are cooler.

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core

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The center of the sun where temperatures and pressures are so high that nuclear fusion occurs.

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corona

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The outermost layer of the Sun's atmosphere that appears like a halo but that is only visible during a solar eclipse.

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dwarf planet

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An object that orbits the Sun, has enough mass and gravity to form a sphere, and has objects similar in mass orbiting near it or crossing its orbital path.

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fusion

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the process by which the nuclei of two atoms (usually hydrogens) merge into one heavier nucleus and release massive amounts of energy.