Perigee		The portion of Saturn's rings on either side of the planet.
Airburst		A circulation cell which forms at the mid-latitudes of a rotating planet to balance the transport by the Hadley and polar cells.
Apollo Asteroids		Tidal forces cause orbits to go to a state of lowest energy while conserving angular momentum.
Aeronomy		The study of the upper atmosphere of the Earth or another planet.
Ionosphere		Caused when the Earth passes through the dust of a comet's tail.
Thermosphere		The closest planet to the Sun.
Asteroid Belt		The region between the orbits of Mars and Jupiter in which most asteroids are found.
Mercury		What a meteorite is called as it is falling through the sky.
Horse Latitudes		The periapsis of an elliptical orbit around the Earth.
Meteor		A protoplanetary disk.
Tides		A weakly ionized region of the Earth's atmosphere which conducts electricity
Black Drop Effect		A class of asteroids with Earth-crossing orbits.
Meteor Shower		One of the four cells created by convection currents on a rotating planet.
Ferrel Cell		A law giving the approximate distances of the planets from the Sun
Amor Asteroid		The latitudes where the Hadley and Ferrel cells meet.
Proplyd		The appearance of a dark band connecting Venus and the Sun during the beginning and end of transits.
Bode's Law		The region of the Earth's atmosphere from roughly 80-500 km altitude. It includes the ionosphere.
Hadley Cell		The explosion of an asteroidal meteorite which has entered the Earth's atmosphere before it reaches the ground.
Ansae		A liquid-giant planet whose atmosphere is composed of hydrogen and helium, with methane, ammonia, H2S, and water as condensable aerosols.
Jupiter		A class of asteroids with Mars-crossing orbits.