Astronomical Unit (AU)7.6 - Be able to use the astronomical unit (1 AU = 1.5 × 108 km)...
The Earth rotates around the Sun in an elliptical orbit. This means it orbits in a slight oval shape.
At some point in the year it is nearer the Sun, At another point it is further away. See the Aphelion & Perihelion page for more information. We therefore make an average.
The mean average distance from Earth to the Sun is 149,600,000 km.
This is called 1 Astronomical Unit, or AU. This figure is a standard number in astronomy. Many distances to planets and stars are calculated using this number.
It is normally rounded to 150,000,000 km.
- What is the AU?
- How many km is the AU?
- Why is this number important to astronomers?