Is the earth in a non-inertial reference frame?

[deadscientist]

So I would agree that it has a uniform tangential velocity but would the centripetal acceleration of the Earth put it in a non inertial frame.

 

[A.T.]

The rest frame of the Earth is noninertial due to rotaion around its own axis. As for the centripetal accelleration due to suns gravity, it depends which theory of gravity you use:

In Newtons model gravity is a real force that causes proper acceleration, which makes orbiting bodies noninertial (even nonrotationg ones).

In general relativity free falling objects are inertial, but inertial frames exist only locally, at the center of the planet. The surface is very noninertial.