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A subduction zone forms where two oceanic plates collide.
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Strike slip faults are caused by shear forces.
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Tsunamis are caused by earthquake motion on the ocean floor.
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At a transform plate boundary plates grind past each other.
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At a divergent plate boundary plates move apart.
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The layer on which the tectonic plate moves is the asthenosphere.
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Smaller pieces of rock from old, broke-up comets become meteoroids.
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Small pieces of rock that enter Earth’s atmosphere at speeds of 15 to 70 km/s and burn up are called meteors.
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Meteoroids are pieces of rock that strike the surface of a moon or planet.
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The positions of the constellations appear to change throughout the year because earth revolves around the Sun.
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About 90 percent of the stars in space are main sequence stars.
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The hottest stars in space are blue in color.
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A star begins as a nebula a large cloud of gas and dust.
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Our sun is considered average because its temperature and absolute magnitude place it in the main sequence range of the H-R diagram.
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Two stars orbit each other in a binary star system.
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The spiral shape of the Milky Way Galaxy cannot be seen from Earth because we are located within one of its spiral arms.
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The Big Bang Theory states that between 15 and 20 billion years ago, the universe began expanding out of an enormous explosion.
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The crust and upper mantle make up Earth’s lithosphere.
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Plates of the lithosphere float on the asthenosphere.
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Plates move apart at divergent boundaries.
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The modified Mercalli scale measures the intensity of an earthquake.
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The Richter scale is based on measurements of the amplitude of a seismic wave.
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When a volcano erupts, the molten material that flows onto Earth’s surface is called lava.
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The phase of the Moon that immediately precedes the New Moon is the waning crescent.
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Dark- colored, relatively flat region of the Moon’s surface that were formed when interior lava filled large basins are called maria.
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A solar eclipse occurs when the Moon moves directly between the Sun and Earth and throws a shadow on Earth.
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Jupiter’s gravity may have been too great for a planet to form in the asteroid belt.
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A comet develops a coma because of heat from the Sun.
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A comet develops a tail because of the solar wind.
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The Sun produces energy by fusing hydrogen atoms into helium atoms in its core.
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A galaxy that has a shape similar to a football is a elliptical galaxy.
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A black hole is a region so dense that nothing, including light, can escape its gravity field.
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Plates slide past one another at transform boundaries.

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The boundary between two plates moving together is called convergent boundaries.
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Active volcanoes are most likely to form at convergent oceanic continental boundaries.
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Mountain ranges are formed when two continental plates collide.
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Molten rock beneath Earth’s surface is called magma.
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Thinner, easy flowing lavas are rich in iron and magnesium.
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Sticky, thicker lavas are rich in silica.
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A composite volcano sometimes erupts violently, is steep sided, and is composed of alternating layers of lava and tephra.
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A shield volcano erupts with thin basaltic lava.
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The Sun’s rays strike Earth at their northernmost and southernmost positions during winter and summer solstices.
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The yearly orbit of Earth around the Sun is called its revolution.
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The presence of Maria on the moon indicates that the moon contains lava beneath its surface.
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Summer occurs on the hemisphere of Earth that is tilted toward the Sun.
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Most of the frozen ice in a comet’s nucleus vaporizes after the comet’s many trips around the
Sun.
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In 1543, Copernicus published his views of Earth and other planets revolving around the Sun.
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Scientists hypothesize that the Sun formed from a cloud of gas and dust.
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The structure of a comet is considered to be like a large, dirty snowball or a mass of frozen ice
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 and rock.
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The Sun was formed when energy caused by nuclear fusion in the center of the clouds of gas and dust radiated into space.
Water is found as a solid, liquid, and gas on Earth.
Planets formed from gas, ice, and dust left over from the formation of the Sun at the center of the cloud.
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The coolest stars in the sky are red in color.
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A sequence of star colors from hottest to coolest is blue, yellow, orange, red.
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Constellations are patterns of stars in the sky.
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As Earth travels in its orbit different constellations are visible at different times of the year.
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A measure of the amount of light received on earth is a star’s apparent magnitude.
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Parallax is the apparent shift in the position of an object when viewed from two locations.