• The inner planets are: Mercury, Venus, Earth, and Mars. They are relatively small, composed mostly of rock, and have few or no moons.
• The outer planets include: Jupiter, Saturn, Uranus, and Neptune. They are mostly huge, mostly gaseous, ringed, and have many moons (plus Pluto, which is a dwarf planet that has one large moon and two small moons).

• Asteroids (also called minor planets) are rocky or metallic objects, most of which orbit the Sun in the asteroid belt between Mars and Jupiter.
• Comets are small, icy bodies that orbit the sun. They have very long tails.
• Meteoroids are small bodies that travel through space. They are stony and/or metallic and are smaller than asteroids. Most are very tiny.

From the Earth, our Milky Way Galaxy is visible as a milky band that stretches across the night sky. It is easier to see when you are far from bright city lights.

To reach the center of the Milky Way Galaxy starting from the Earth, aim toward the constellation Sagittarius. If you were in a spacecraft, during the trip you would pass the stars in Sagittarius one by one (and many other stars!).