Chapter 17 Earth in Space Vocabulary
the Sun and all the bodies that orbit it Solar system the Sun and all the bodies that orbit it
one full orbit of an object around another object revolution one full orbit of an object around another object
an imaginary center line around which the earth rotates axis an imaginary center line around which the earth rotates
one whole spin of an object on its axis rotation one whole spin of an object on its axis
a spacecraft that gathers data without a crew space probe a spacecraft that gathers data without a crew
a frozen mass of ice and dust orbiting the Sun comet a frozen mass of ice and dust orbiting the Sun
asteroid a rocky mass up to several hundred kilometers wide that revolves around the Sun
an object in orbit around another object satellite an object in orbit around another object
Moon phase An indication of the fraction of the Moon that is illuminated as seen from Earth