Contact Bob | About this Site | Site Map
Bob the Alien's Tour of the Solar System
The Sun Mercury Venus Earth The Moon Mars Jupiter Saturn Uranus Neptune Pluto and Dwarf Planets Comets


Space A to Z

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - XYZ

Word Meaning
Earth The third planet from the Sun and the fifth largest planet in the Solar System. The only planet in the Solar System where large quantities of water exist, and the only planet in the Universe on which life is known to exist. Earth has one natural satellite (the Moon).
EDT Eastern Daylight Time. The time used during Spring and Summer on the East Coast in the United States , the west coast in South America, the Bahamas and some Caribbean islands. The time is four hours behind GMT (Greenwich Mean Time) or UTC (Universal Time Coordinate). As Eastern Daylight Time is used in Florida, it is sometimes used when describing the times of space launches from Kennedy Space Center in Florida.
EST Eastern Standard Time. The time used during Autumn/Fall and Winter on the East Coast of North America, the west coast in South America, the Bahamas and some Caribbean islands. The time is five hours behind GMT (Greenwich Mean Time) and UTC (Universal Time Coordinate). As Florida falls under Eastern Standard Time, many launches from Kennedy Space Center are referred to under the EST time.
Elara
Element Chemical material in its simplest form, such as hydrogen, helium, oxygen, carbon, etc. An element can be a solid, a liquid or a gas. Matter is made up of many elements. There are 105 elements in total. The Solar System was formed out of a cloud of matter. The elements in this matter combined with other elements as they formed the Sun and planets. For example, when carbon combined with oxygen, it formed carbon dioxide.
Elliptical/Ellipse An elongated circle. Most of the planets in the Solar System don't orbit in perfect circles; instead their orbits are elliptical, meaning that they may be oval shaped and sometimes the Sun isn't exactly central. Venus has the most circular orbit, whereas dwarf planets like Pluto and Eris are the most eliptical.
Enceladus moon of saturn
Enceladus
Epimetheus moon of saturn
Erinome moon of jupiter
Escape Velocity The minimum velocity (or speed) that an object needs to be travelling at to escape the gravitational pull of a much larger object. For example, for a rocket to leave the orbit of Earth, it needs to reach a certain velocity or else it will fall back to Earth. On planets and moons with a smaller pull of gravity (the Moon, Mars), the velocity needed to leave that object would be much less.
ESA European Space Agency. A group of fifteen European (believe it or not!) countries which design, develop and launch satellites and probes into space. ESA's most notable missions are Mars Express and Venus Express. The ESA works with other space agencies around the world, like NASA and the Russian Space Agency, and has Canada as a cooperating state. The nations which make up the ESA are Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
Erriapus moon of saturn
Event Horizon The boundary of a black whole. The pull of gravity beyond this point is so great that for any matter to escape it, it must be travelling faster than the speed of light.
Euanthe moon of jupiter
Eukelade moon of jupiter
Europa moon of jupiter
Eurydome moon of jupiter
Exoplanet/Extrasolar Planet A planet which orbits another star in the Universe. By June 2007, there were 242 planets known to orbit other stars. Most exoplanets are detected by the effect they have on their host stars and haven't actually been imaged. Most known exoplanets are more like Jupiter than Earth (since a planet like Earth won't have a very visible effect on its host star so isn't known about). Although few Earth-like planets are known to exist, it is certain that several of them do exist which greatly increases the chances of life existing or being able to exist elsewhere in the Universe.
Extra Terrestrial Literally means "not of" or "beyond the Earth". Refers to anything that doesn't belong to planet Earth. An Extra Terrestrial would be a being from another planet, or an alien.

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - XYZ