UNIT 4: EARTH AND SPACE

rotation

the spinning of an object on its OWN axis

revolution

the movement of one object around another

astronomical unit

the average distance between Earth and the Sun—> 1 AU = 150 million kilometers away

comet

a small, icy object that orbits the sun and has a long "tail" of gas

light-year

the distance light travels in one year which is 9.4607 × 10^12 km (nearly 6 trillion miles)

asteroid

a small object in space that range from a grain of sand to bigger, mostly originate in the asteroid belt of mars and jupiter

constellation

a group of stars that seems to form a distinctive pattern

celestial objects

any object that exists in space

retrograde motion

the movement of an object in the sky, usually a planet, from east to west, rather than in its normal motion from west to east

orbital radius

the avg distance between the sun and an object that is orbiting the sun

meteors

a meteroid that hits earths atmosphere and burns up

meteorites

a meteroid that is large enough to pass through earths atmosphere and reach the ground without being totally burned up

nebula

a vast cloud of gas and dust which may be the birthplace of stars and planets

apparent magnitude

measures how bright an object appears from Earth