Is "rotate" in "Earth rotates around the sun" the correct word?
Earth rotates around the sun.
Is rotate an acceptable word in that context or should I use words such as orbit or revolve instead?
I disagree with the choice of the word "rotate," which is most properly used to describe angular motion around the Earth's own axis. "Orbit" is more proper, because it denotes angular motion of the line joining the axes of the Earth and the Sun around the axis of the Sun.
The Earth rotates around its poles and orbits around the Sun.
Here is a Google Ngram chart comparing the frequency of occurrence in the Google Books database of "rotates around the sun" (blue line) versus "revolves around the sun" (red line) versus "orbits the sun" (green line) for the years 1868–2008:
And here is the Ngram chart for "rotation around the sun" (blue line) versus "revolution around the sun" (red line) versus "orbit around the sun" (green line) for the same time period:
From these charts, it appears that the "rotates around the sun"/"rotation around the sun" pair is much less common in published writing than either "revolves around the sun"/"revolution around the sun" or "orbits the sun"/"orbit around the sun." Taking into account this strong preference in written usage, I can't think of any reason to prefer the "rotates"/"rotation" wording when describing a planet that is proceeding on its elliptical circuit around a star.
The distinction between rotate and revolve is taught to all students. I would mark the misuse in people older than 6th graders (see the link for 6th grade education std. below). For what ever reason, this has been a sort of litmus test in the scientific community for a long time, and it may as well be public knowledge.
See objective 2a in the link below.
Objective 2 Demonstrate how the relative positions of Earth, the moon, and the sun create the appearance of the moon’s phases.
a. Identify the difference between the motion of an object rotating on its axis and an object revolving in orbit.
http://www.uen.org/core/core.do?courseNum=3060