Dwarf Planet—Objects orbiting the Sun that are big and heavy
enough to resemble a planet,but not quite big enough to have
their own clear orbit around thesun. Example: Pluto
Galaxy—A grouping of billions of stars held together by
gravity.Overall shapes of galaxies include spiral, elliptical, and
irregular.
Gas Planet—Planets made of mostly gas and lacking a clearly
defined surface. The gas planetsare sometimes called the Jovian,
or giant, planets. Thegas planets in our solar system include
Jupiter,Saturn, Neptune, and Uranus.
Inner Planet—The first four planets orbiting the Sun before the
asteroid belt. The inner planetsinclude Mercury, Venus, Earth,
and Mars.
Moon—A natural satellite orbiting a planet.
Orbit—The path followed by planets and other space objects
as they revolve around objects that havea larger gravity, like
the Sun.
Outer Planet—Any of the planets that orbit the Sun outside
the asteroid belt. Outer planetsinclude Jupiter, Saturn, Uranus,
Neptune, and Pluto (dwarfplanet).
Rocky Planet—Any of the planets that has a solid surface.
Rocky planets are also calledterrestrial planets. The rocky
planets include Mercury,Venus, Earth, and Mars.
Star—Giant burning balls of hydrogen and helium gas that give
offboth light and heat. Red and orange stars are cooler than
hotter white or blue colored (coloured)stars. The Sun, although
large to everyone on Earth, is consideredto be an average star
in size (about 1,392,000km or 864,000 miles across). Many dwarf
stars are smaller than the Sun. Larger stars can be100, 300, and
even 1,000 times larger than theSun. Polaris (the North Star) is
about 46 times bigger thanthe Sun. Sirius (the brightest star in
the northern hemisphere) is actuallytwo stars (Sirius A and B)