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This might be a weird question, but I'll ask it anyway.

If one year on earth is the time it takes for the earth to orbit around the sun, then (if it were possible for humans to survive on the sun), how long would be a year on the sun?

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closed as unclear what you're asking by called2voyage Jul 3 '14 at 20:05

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question.If this question can be reworded to fit the rules in the help center, please edit the question.

It's not exactly clear what you're looking for (the whole "what if humans could live on the sun" part makes this seem like speculation about human standards instead of an astronomical question), but perhaps you're looking for this: Galactic year - Wikipedia? – called2voyage Jun 17 '14 at 19:35
up vote 9 down vote accepted

There are (at least) two possible answers.

  1. The concept of a "year" has no meaning for the Sun. For Earth, a year is the time it takes to complete one orbit around the Sun. Since the Sun doesn't orbit around the Sun, it doesn't have a year.

  2. But the Sun does orbit around the core of the Milky Way Galaxy. One orbit takes from 225 million to 250 million years. (Current estimates are uncertain, and the chaotic nature of star motions is likely to cause it to vary a bit.) This is called a "galactic year" or "cosmic year". Reference:

(I suppose there could be a third answer. If humans were able to put a colony on the surface of the Sun, using some advanced technology that obviously doesn't exist yet, it's likely they'd still use an Earth-based calendar to measure time.)

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I hope you mean if a sun was 'rotating around' another sun, how long it would take to complete a revolution.

There is this thought process. Since they both have equal mass, they would definitely rotate around their center of mass. So now, many factors come into the picture.

  • Distance: How far they are from each other.
  • Mass: Mass of sun, i.e. their individual masses (same in this case of course)

Using the mass and distance we can make some basic calculations using $F = G*\frac{M^2}{d^2}$, where $M$ is the mass of sun and $d$ is the distance of separation between the two 'suns'. Keeping in mind of the fact they must obviously be rotating about their center of mass which is half-way in this case, we can use $a = \frac{v^2}{r}$ accordingly and get to the solution you are seeking.

So, depending on the above factors (there may be few more), we may find the linear or angular velocity with which they are rotating around their center of mass, and accordingly we can calculate the period of rotation.

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