[Physics] 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

Best Answer

The Sun will never return to the 'same spot' (e.g. relative to the Solar System centre of mass) because the orbital periods of Solar System bodies are not all rational multiples of each other. By far the largest influence on the Sun's position is caused by Jupiter (can check this by computing the force exerted by each planet). So to a decent approximation, the period of the Sun's year as you've defined it is 1 jovian year.

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