To learn about the Solar System, it helps to understand coordinates that can be used to describe it.
You may have seen coordinates on an x-y graph – x goes horizontally and y goes vertically. The graph at the right is a very simple graph of x and y.
But to make a graph of the Solar System, we need to use a different type of coordinates. We are looking from Earth, and Earth is a sphere. So we must use coordinates that can work on the surface of a sphere. The coordinates for the sky are based on coordinates for the Earth.
Click Next to learn about how Earth coordinates work.