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Where do solar spot names come from?

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AR stands for "Active Region", with which a Sunspot usually is.  Sunspots are cooler than the rest of the sun and it is that coolness that makes them a darker colour.

I believe the number is just a numbering system, with the 1st one being spotted and confirmed being AR0001, and so on.

Just dug this of the web, helps explain the system a little better....

"There is no naming or numbering system for sunspots. There is a system for numbering active regions, however. An active region can contain one or more spots. The National Oceanic and Atmospheric Administration (NOAA) numbers active regions consecutively as they are observed on the Sun. According to David Speich at NOAA, an active region must be observed by two observatories before it is given a number (a region may be numbered before its presence is confirmed by another observatory if a flare is observed to occur in it, however). The present numbering system started on January 5, 1972, and has been consecutive since then. An example of an active region "name" is "AR5128" (AR for Active Region) or "NOAA Region 5128". Since we only see active regions when they are on the side of the Sun facing the Earth, and the Sun rotates approximately once every 27 days (the equator rotates faster than the poles), the same active region may be seen more than once (if it lasts long enough). In this case the region will be given a new number. Hence, a long-lived active region may get several numbers.

On June 14, 2002, active region number 10000 was reached. For practical, computational reasons, active region numbers continue to have only four digits. Therefore, the sequence of numbers is 9998, 9999, 0000, 0001, and so on. Active region number 10030, for example, is AR0030. This region will often simply be referred to as region number 30, with 10030 implied. "

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And I guess that active region number 10030, AR0030, is not confused with the original number 30 in 1972, because so much time has passed and a sun spot loses its relevance very quickly after it disappeared.

I see there are websites that show the current sunspots, like http://www.solarham.net/.

Edited by Linda

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I guess so yes.

Like the article explains, if there is persistent AR then it can have a number of AR references.

But I guess the NOAA have a very extensive catalogue detailing all AR regions with numbers far bigger than the AR 9999 limit.

I like using this website for all things sun / atmosphere ......



Edited by Daz Type-R

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Each rotation of the sun also has a unique number. The current rotation is 2176.

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