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Defend Earth from alien invaders
A rocky object revolving around the sun that is too small and numerous to be considered as a planet.
The region of the solar system, between the orbits of Mars and Jupiter, where many asteroids are found.
The middle layer of the sun's atmosphere.
The fuzzy outer layer of a comet.
A loose collection of ice, dust, and a small rocky particles, typically with a long, narrow orbit.
The outermost layer of the sun's interior.
The central region of the sun, where nuclear fision takes place.
The outer layer of the sun's atmosphere.
An oval shape, which may be elongated or nearly circular; the shape of the planet's orbits.
a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy.
The name often given to the first four outer planets: Jupiter, Saturn, Uranus, and Neptune.
A model of the universe in which Earth is at the center of the revolving planets and stars.
The trapping of heat by a planet's atmosphere.
A model of the solar system in which Earth and the other planets revolve around the sun.
A doughnut-shaped region that stretches from beyond Neptune's orbit to about 100 times Earth's distance from the sun.
A streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere.
A meteoroid that passes through the atmosphere and hits Earth's atmosphere.
A chunk of rock or dust in space.
The solid inner core of a comet.
A sperical region of comets that surrounds the solar system.
The inner layer of the sun's atmosphere that gives off its visible light.
A region of very tightly packed gas in the sun's interior where enrgy is transferred mainly in the form of light.
A thin disk of small ice and rock particles surrounding a planet
An eruption of gas from the sun's surface that occurs when the loops in sunspot regions suddenly connect.
A stream of electrically charged particles that emanate from our solar system.
A dark area of gas on the sun's surface that is cooler than surrounding gases.
The name often given to the four inner planets: Mercury, Venus, Earth, and Mars.
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