• A subduction zone forms where two oceanic plates collide.
  • Strike slip faults are caused by shear forces.
  • Tsunamis are caused by earthquake motion on the ocean floor.
  • At a transform plate boundary plates grind past each other.
  • At a divergent plate boundary plates move apart.
  • The layer on which the tectonic plate moves is the asthenosphere.
  • Smaller pieces of rock from old, broke-up comets become meteoroids.
  • Small pieces of rock that enter Earth’s atmosphere at speeds of 15 to 70 km/s and burn up are called meteors.
  • Meteoroids are pieces of rock that strike the surface of a moon or planet.
  • The positions of the constellations appear to change throughout the year because earth revolves around the Sun.
  • About 90 percent of the stars in space are main sequence stars.
  • The hottest stars in space are blue in color.
  • A star begins as a nebula a large cloud of gas and dust.
  • Our sun is considered average because its temperature and absolute magnitude place it in the main sequence range of the H-R diagram.
  • Two stars orbit each other in a binary star system.
  • The spiral shape of the Milky Way Galaxy cannot be seen from Earth because we are located within one of its spiral arms.
  • The Big Bang Theory states that between 15 and 20 billion years ago, the universe began expanding out of an enormous explosion.
  • The crust and upper mantle make up Earth’s lithosphere.
  • Plates of the lithosphere float on the asthenosphere.
  • Plates move apart at divergent boundaries.
  • The modified Mercalli scale measures the intensity of an earthquake.
  • The Richter scale is based on measurements of the amplitude of a seismic wave.
  • When a volcano erupts, the molten material that flows onto Earth’s surface is called lava.
  • The phase of the Moon that immediately precedes the New Moon is the waning crescent.
  • Dark- colored, relatively flat region of the Moon’s surface that were formed when interior lava filled large basins are called maria.
  • A solar eclipse occurs when the Moon moves directly between the Sun and Earth and throws a shadow on Earth.
  • Jupiter’s gravity may have been too great for a planet to form in the asteroid belt.
  • A comet develops a coma because of heat from the Sun.
  • A comet develops a tail because of the solar wind.
  • The Sun produces energy by fusing hydrogen atoms into helium atoms in its core.
  • A galaxy that has a shape similar to a football is aelliptical galaxy.
  • A black hole is a region so dense that nothing, including light, can escape its gravity field.
  • Plates slide past one another at transform boundaries.
  • The boundary between two plates moving together is called convergent boundaries.
  • Active volcanoes are most likely to form at convergent oceanic continental boundaries.
  • Mountain ranges are formed when two continental plates collide.
  • Molten rock beneath Earth’s surface is called magma.
  • Thinner, easy flowing lavas are rich in iron and magnesium.
  • Sticky, thicker lavas are rich in silica.
  • A composite volcano sometimes erupts violently, is steep sided, and is composed of alternating layers of lava and tephra.
  • A shield volcano erupts with thin basaltic lava.
  • The Sun’s rays strike Earth at their northernmost and southernmost positions during winter and summer solstices.
  • The yearly orbit of Earth around the Sun is called its revolution.
  • The presence of Maria on the moon indicates that the moon contains lava beneath its surface.
  • Summer occurs on the hemisphere of Earth that is tilted toward the Sun.
  • Most of the frozen ice in a comet’s nucleus vaporizes after the comet’s many trips around the Sun.
  • In 1543, Copernicus published his views of Earth and other planets revolving around the Sun.
  • Scientists hypothesize that the Sun formed from a cloud of gas and dust.
  • The structure of a comet is considered to be like a large, dirty snowball or a mass of frozen ice and rock.
  • 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.
  • The coolest stars in the sky are red in color.
  • A sequence of star colors from hottest to coolest is blue, yellow, orange, red.
  • Constellations are patterns of stars in the sky.
  • As Earth travels in its orbit different constellations are visible at different times of the year.
  • A measure of the amount of light received on earth is a star’s apparent magnitude.
  • Parallax is the apparent shift in the position of an object when viewed from two locations.