The Sun - a ball of hydrogen and helium. The source of energy and magic. It is 1,391,980km large. The temperature is 10,000 F. It is also called Sol.

The planets are divided by inner and outer planets. The inner planets are Mercury, Venus, Earth, and Mars. All of these have rocky surfaces.

Mercury - Has no moons. It has a thin atmosphere made mostly of oxygen, sodium, and helium. Its atmosphere has 200 trillion times less pressure than Earth.

Venus - Has no moons. It has a thick sulphuric acid cloud layer. The surface cannot be seen through the clouds. The atmosphere is 92 times more pressure than Earth.

Earth - Has one moon (Luna or Selena).

Mars - Looks red because of iron oxide. The atmosphere is 100 times less pressure than Earth's. It has two moons, Phobos and Deimos.

Then there is the Asteroid Belt that seperates the inner planets from the outer planets. The outer planets are Jupiter, Saturn, Uranus, and Neptune. They are made of gas and have no surface. All have rings, but only Saturn's are bright enough to see through a small telescope.

Jupiter - Has ammonia crystal clouds. The Great Red Spot is the largest of the vortexes. It has 79 known moons. The largest are Io, Europa, Ganymede, and Callisto.

Saturn - Has rings made of frozen water. They are only 20m thick. Galileo called the rings "ears". It has 82 known moons.

Urnaus and Neptune - Can't be seen with the naked eye. Uranus has 27 moons, Neptune has 14. 

Ptolomy believed the planets moved in circles around the Earth. Aristarchus believed in a heliocentric model. Copernicus wrote about this idea 18 centuries later. Galileo later confirmed this model. Kepler then expanded on Galileo's model.

Kepler's first law is that planets revolve around the sun in an ellipse, and that the sun isn't right in the middle.

The second law is that there is an imaginary line between the sun and a planet that show equal time and equal area. A planet will speed up as it approaches the sun.

The third law says if you divide the square of time for a planet to revolve around the sun by the cube of the average distance, you will always get the same answer.

Orbit - The path of a planet around the sun, or moon around a planet.

Aphelion - The farthest distance between planet and sun.

Perihelion - The nearest distance between planet and sun.

Apogee - The farthest distance between moon and Earth.

Perigee - The nearest distance between moon and Earth.

Length of Orbit - The perihelion and aphelion added together.

Eccentricity - The amount by which the sun is off center.