galileanmoons		Theory suggesting that the Moon was captured by Earth's gravitational pull and brought closer.
greatdarkspot		Bowl-shaped depression.
regolith		Type of greenhouse effect where a planet's atmosphere increases its ability to retain heat.
crater		Long-lived storm system in Neptune's atmosphere.
runaway		Theory suggesting that the Moon formed from an impact of a Mars sized object.
seasonal		Surface dust.
synchronousorbit		Eastward and westward atmospheric flow; symmetrical about the equator.
shepherdsatellites		Gravitational pull of a moon that helps keep the planet's ring(s) in shape.
tidallocking		Theory suggesting that the Moon formed from the Earth.
capture		Long-lived hole in clouds that permits astronomers to see into Jupiter's lower atmosphere.
zonalflow		Forces that cause a satellite to rotate at the same rate it revolves around its parent planet.
coorbitalsatellites		Thin, flat rings surrounding gaseous planets.
impact		The four large moons of Jupiter.
daughterfission		Occurs when a planet's or moon's orbit is equal to its average orbital period.
retrogrademotion		Regions on Mercury that are relatively smooth.
greatredspot		Martian polar ice cap that grows and shrinks.
residual		Long-lived storm system in Jupiter's atmosphere.
maria		An apparent backward loop traced by a planet.
highlands		Rotating storm system near the Great Red Spot.
intercraterplains		When rotation rates are unequal at the equator and the poles of a gaseous planet.
whiteovals		Dark, smooth, basaltic features on the lunar surface.
brownovals		Regions on the lunar surface that are elevated above maria.
planetaryringsystem		Moons that share the same orbit.
differentialrotation		Martian polar ice cap that remains permanently frozen.
sistercoformation		Theory suggesting the Moon formed as a separate oject close to Earth.