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**Joshua Flynn**

...When does the next solar rotation (of 28 days) start?

Or, alternately, when was the last start?

**Rager** lop guest User ID: 28486 04-29-2011 12:49 PM

well, at the equator of the sun the rotations are every 24 days, dont know if that is what you are looking for.

**Teal Dear** lop guest User ID: 23013 04-29-2011 12:50 PM

Hmm... it's kind on an ill-formed rotation. The equator and poles turn at different rates, and the points on the surface are in pretty quick flux with each other. Picking a constant "point" on the surface hasn't really been done because the features move.

**Joshua Flynn**

R.A.T.W. Wrote:

well, at the equator of the sun the rotations are every 24 days, dont know if that is what you are looking for.

It is. Sorry, I got confused by this:

"but instead often uses the definition of a Carrington rotation: a synodic rotation period of 27.2753 days"
http://en.wikipedia.org/wiki/Solar_rotation

**Joshua Flynn**

Teal Dear Wrote:

Hmm... it's kind on an ill-formed rotation. The equator and poles turn at different rates, and the points on the surface are in pretty quick flux with each other. Picking a constant "point" on the surface hasn't really been done because the features move.

That would complicate things. But if there's no specific start point (similar to a full moon for example), then I'll just work with the rotational days.

**Joshua Flynn**

So no start date/end date of the rotational sequence then?

**OTOC**

Joshua Flynn Wrote:

So no start date/end date of the rotational sequence then?

Yes there are many.

Any moment can be the start of a new one.

Features on the sun are not common (Stable) though so what are they meant to do? Especially back when we could only see about half of the sun.

**Teal Dear** lop guest User ID: 23013 04-29-2011 01:45 PM

Joshua Flynn Wrote:

Teal Dear Wrote:
Hmm... it's kind on an ill-formed rotation. The equator and poles turn at different rates, and the points on the surface are in pretty quick flux with each other. Picking a constant "point" on the surface hasn't really been done because the features move.

That would complicate things. But if there's no specific start point (similar to a full moon for example), then I'll just work with the rotational days.

Right: there's no common meridien, but people have been tracking how fast sunspots move since .... ? (It was in Pisa, so I want to say Galileo...) Since Italy was a major scientific power? Sorry, Italy. Baby, don't look that way. You know I love you.

If you work with rotational days, make the parameter a variable. You'll want to check 24d up to 28d and find a "best fit"... Because the difference in rotation rates builds charges, it drives solar weather, so the "key component" might be some kind of beat period between polar minimum and equatorial maximum...

Yeah, I didn't know I knew all this either... It's been since 1997...

**Joshua Flynn**

Teal Dear Wrote:

Right: there's no common meridien, but people have been tracking how fast sunspots move since .... ? (It was in Pisa, so I want to say Galileo...) Since Italy was a major scientific power? Sorry, Italy. Baby, don't look that way. You know I love you.

If you work with rotational days, make the parameter a variable. You'll want to check 24d up to 28d and find a "best fit"... Because the difference in rotation rates builds charges, it drives solar weather, so the "key component" might be some kind of beat period between polar minimum and equatorial maximum...

Yeah, I didn't know I knew all this either... It's been since 1997...

It's already a variable, but I'll implement a custom variable-variable. The only problem with this is the tweaking could easily become confirmation bias for any ideas I might establish.

The Janitor. Wrote:

Features on the sun are not common (Stable) though so what are they meant to do? Especially back when we could only see about half of the sun.

Use the STEREO satellites, implement some software image tracking of all the sun's features (both satellites), track for a day (storing speed continually), using the different features, eliminate independent feature movement, work out common feature movement, work out speed of common feature movement. Done. Rotation of the sun figured.

**aVian**

R.A.T.W. Wrote:

well, at the equator of the sun the rotations are every 24 days, dont know if that is what you are looking for.

no matter where you are on the sun, its the same time as at the equator, its however a shorter distance, but no less time. chuckle

**Teal Dear** lop guest User ID: 23013 04-29-2011 02:17 PM

Joshua Flynn Wrote:

Teal Dear Wrote:
Because the difference in rotation rates builds charges, it drives solar weather, so the "key component" might be some kind of beat period between polar minimum and equatorial maximum...

It's already a variable, but I'll implement a custom variable-variable. The only problem with this is the tweaking could easily become confirmation bias for any ideas I might establish.

That's okay -- your first round is just a hypothesis. You'll need NEW data for confirmation. It's OK to make bad predictions. Consider the diff. between a hypothetical polar rotatation (24d) and a hypothetical equatorial rotation (28d). The initial conditions shift from each other 2.143deg/d and will be 180deg from each other in about 84d. I'd expect changes in solar weather to follow THAT pattern because that's when the differential would be maximum. So, at first, you're just looking for the pattern... any confirmation bias is just an indicator of a pattern to explain.

Of course, they let me brute force most problems for about a quarter here before they want results.