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33 terms


a model of the universe in which earth is at the center of the revolving planets and stars
a model of the solar system in which Earth and the other planets revolve around the sun
an oval shape, which may be elongated or nearly circular
solar system
system made up of the nine unique planets, including earth, and many smaller objects, that orbit the sun.
astronomical unit
A unit of length used for distances within the solar system
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
dwarf planet
a large round object that revolves around the sun but has not cleared the region around its orbit
one of the small asteroid-like bodies that formed the building blocks of the planets
the central region of the sun where nuclear fusion takes place
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
radiation zone
a region of very tightly packed gas in the sun's interior where energy is transferred mainly in the form of light
convection zone
the outermost layer of the sun's interior
the inner layer of the suns atmosphere that gives off its visible light
the middle layer of the sun's atmosphere
the outer layer of the sun's atmosphere
solar wind
the blocking of gas from the sunlight to the earth that occurs when the moon is directly between the sun and earth
a dark area of gas on the sun that is cooler than surrounding gases
A huge, reddish loop of gas that protrudes from the sun's surface, linking parts of sunspot regions
solar flare
an eruption of gas from the sun's surface that occurs when the loops in sunspot regions suddenly connect
terrestrial planets
The name given to the four inner planets: Mercury, Venus, Earth, and Mars
greenhouse effect
the trapping of the heat near a planets surface by certain gases in the planets atmosphere
gas giant
The name often given to the first four outer planets: Jupiter, Saturn, Uranus, and Neptune.
a thin disk of small ice and rock particles surrounding a planet
asteroid belt
the region of the solar system between the orbits of Mars and Jupiter, where many asteroids are found
kuiper belt
a region of the solar system that is just beyond the orbit of neptune and that contains small bodies made mostly of ice
oort cloud
a spherical region of comets that surrounds the solar system
loose collections of ice, dust, and small particles whose orbits are usually very long, narrow ellipses
the fuzzy outer layer of a comet
the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities
Objects revolving around the sun that are too small and too numerous to be considered planets
A chunk of rock or dust in space.
a streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere
a meteoroid that strikes the surface of a moon or planet