# What is the difference between “rotation around / along” an axis?

Is there any difference between the expressions:

1. rotate the vector around an axis
2. rotate the vector along an axis ?

Hint: The context is a sphere with vectors located on it, each originating in the the centre of the sphere.

Thanks.

• In general, non-technical, colloquial parlance, I would use them interchangeably. If there is a technical difference in mathematics (or whatever field rotating spheres and vectors belong to), then I at least am not aware of it, and I would wager that most people aren't, either. – Janus Bahs Jacquet Aug 11 '16 at 8:32
• I suspect that mathematicians would say that something translates along a line but rotates about an axis. Rotating around an axis sounds like an orbit - like the moon around the Earth, except that an axis refers to a line, not a point. – Lawrence Aug 11 '16 at 8:54
• I'm flagging this for closure as it's not about standard English usage, it's a technical question on the appropriate term to use in this specific scenario within the field of mathematics, physics or graphics. If some research by the OP (eg technical dictionaries or Wikipedia) fails to reveal the answer, it could be posted on the appropriate SE site – Chappo Aug 11 '16 at 10:04
• @JanusBahsJacquet Yes, that was my thought too. I did not mention it in my question but in fact in the material I had read the two usages appeared together in one sentence. There was a rotation around an axis, followed by a rotation along another axis. And since per definition the origin of a vector could not be changed, there should be only one way to rotate a vector around/along/about an axis. In that particular context at least. – QuantMechanist Aug 12 '16 at 3:49
• Rotate along an axis is just wrong. Rotate about an axis is the usual way to say it. And something revolves around something else. This is hardly specialized usage, I cited a 6th grade science course objective in a different question about revolve/rotate. Google the pair "rotate around/about an axis" and look at the quality of returns. Which bunch do you want to belong to? The guy asking "does the flat earth rotate around an axis or not" was my favorite. – Phil Sweet Aug 12 '16 at 5:25