Hi - I've just started having lectures on special relativity at uni. We were talking about inertial reference frames and how these can be characterised by the facts that: 1) They move relative to one another with constant velocity, and 2) Newton's laws operate in inertial reference frames. Now, we pressume that Newton's laws are true on earth. However, this is not travelling at a constant velocity, since there is a centripetal acceleration towards the sun. So how can we still class the earth as an inertial reference frame? Thanks in adnvance.