Sunspot moved from where it was 3 days ago

Because we couldn’t see the sunspot that was so prominent a few days ago, we decided to take our telescope out to get a closer look. The sunspot we saw three days ago was much closer to the center of the sun’s disk than the one we saw today, leading us to hypothesize that a new sunspot has appeared, nine days ahead of the US eclipse on August 21, and the one we saw a few days ago has disappeared.


The sun on a windy day, noting a sunspot, noon MDT today, 6" Newtonian reflector, f/9.2

But that would be a hasty and ill-advised hypothesis. The sun rotates, so it’s possible—even likely, in fact—that the sunspot we are looking at today is the very same sunspot we saw a few days ago much closer to the center of the sun’s disk. We have this from CalTech:

Yes, the Sun does spin, or rotate. Because it is a gas, it does not rotate like a solid. The Sun actually spins faster at its equator than at its poles. The Sun rotates once every 24 days at its equator, but only once every 35 near its poles. We know this by watching the motion of sunspots and other solar features move across the Sun. The giant gas planets, Jupiter, Saturn, Uranus, and Neptune, also spin faster at their equators than at their poles.

As a result of the sun’s rotation, we don’t really know if this is a new sunspot or just the old one in a new place. After all, we didn’t follow it every step of the way.

(The 3:00 position of the old one compared to the 11:00 position of the one today is insignificant, since we can’t really confirm what angle the camera was pointing without a better frame of reference, which we don’t have.)

About the Author

Paul Katula
Paul Katula is the executive editor of the Voxitatis Research Foundation, which publishes this blog. For more information, see the About page.

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