## A Conversation for Astronomical Units

### Technicality.

shagbark Started conversation Feb 19, 2009

since Our orbit is an ellipse not a circle, somebody came up with a formal definition to keep the AU at a more fixed number

Their definition is:

The radius of an unperturbed circular orbit of a massless body that would revolve about the Sun in one year.

### Technicality.

Gnomon - time to move on Posted Feb 25, 2010

In other words, the radius that the Earth's orbit would have if it were circular.

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