Interactive Orrery

An Orrery is a moving, mechanical model of the Solar System. It shows how all of the planets orbit around the Sun.

A illustration of the planets orbiting the Sun. Each planet has a clock face on it.

Coordinate Systems

We use coordinate systems to identify the position of a point on a surface. When we talk about coordinates, we usually think of geographical coordinates on the surface of the Earth. However, we can use similar systems to locate objects in the night sky. We call these celestial coordinates. When we think about the night sky in this way, we imagine it as a spherical surface around the Earth.