# How long is a 'sun year'?

I know that a 'sun day' is the time that a sun spot takes to orbit one time across the suns surface (25-30 days dependent on location I think) and what is actually defined as a 'sun year' is how long it takes for our solar system to orbit the galaxy.

But I would like to know how long it takes for the centre of the sun to return to its starting point, hence the caption marks marks around 'sun year'

Am I correct to think that the sun translates a very little bit because of the planets rotating around it?
Is it even measurable?

edit: by sun year i mean my definition of sun year, not the standart definition

• Wait, you have two questions here. One about the time for the sun to orbit the center of the galaxy (is that not googleable?). Second about the effect of planets, right? Commented Oct 11, 2015 at 14:01
• no, i know that it takes ~ 250 mil. years for the sun to orbit around the galaxy, i only want to know how long it takes for the center of mass of the sun at a given time to move and return back to that spot relative to that spot. Commented Oct 11, 2015 at 14:06
• Then I do not get at all what you are asking. You already answered your question "How long is a sun year?" with this comment? Commented Oct 11, 2015 at 14:15
• @Bernhard if you ignore the rotation around the galaxy, and only focus on the solar system, how long does it take for the tiny translations of the sun caused by planets to revert the sun to its original position. (for instance, we measure the exact location of the com of the sun at a given point in time, and wait for the com of the sun to return back there, ignoring translation around the galaxy) Commented Oct 11, 2015 at 14:27
• The problem with this question is that it assumes there's a way to measure an absolute position. We can't measure the "exact location" of a "spot relative to that [same] spot." We can only measure relative locations, and taking any reasonable reference point (I.e. one of the Sun's own planets) gives us an answer of "one [reference planet] year." Commented Oct 11, 2015 at 14:39