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Hinode (Sunrise), a project to study the Sun, is exploring
the magnetic fields of the Sun, and is improving our understanding of the mechanisms that power the solar atmosphere and drive solar eruptions.
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The Sunspot Cycle (Cycle 24) is Beginning Slowly. Is it Minimum Yet?
A new cycle region has appeared and was numbered on
25 February, AR 11012. This is the second region to appear in February.
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The image above shows the variation of sunspot number over time for solar cycles 11 (which began around 1867) and cycle 23, which began around 1996.
The background image is from Hinode's X-ray Telescope (XRT). Sunspot cycle 23, peaked in 2001 and produced some of the largest flares on record (the "record" approximately equates to the space age, when we began observing X rays from the Sun). The graphs show the sunspot number versus time. The two cycles have similar shape and size and a long decrease to minimum, but cycle 12 started much more quickly than our new cycle, cycle 24.
Cycle 23 is not really that unusual, although it now has ten months with fewer than five sunspots. Since 1875, two cycles had fewer than five sunspots for 10 and 12 nmonths, one cycle had seven months and another had eight. So, for these 13 minima of the sunspot cycle (since 1875), if you define long minima as cycles with fewer than five sunspots/month, the minima of seven of them (53%, including cycle 23) persisted for six months up to one year.
For more information about the the solar cycle and to see the latest predictions, see David Hathaway's Solar Cycle Prediction page.
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| Active Region Number |
Cycle Number |
Location |
Date Numbered |
| 11013 |
23 (new cycle) |
N26E12 |
25 Feb 2009 |
| 11012 |
23 (old cycle) |
S06E53 |
12 Feb 2009 |
| 11011 |
23 (old cycle) |
S12W34 |
20 Jan 2009 |
| 11010 |
24 (new cycle) |
N18E33 |
10 Jan 2009 |
| 11009 |
24 (new cycle) |
S26W73 |
11 Dec 2008 |
| 11008 |
24 (new cycle) |
N33W09 |
11 Nov 2008 |
| 11007 |
24 (new cycle) |
N35E02 |
31 Oct 2008 |
| 11006 |
24 (new cycle) |
S27W63 |
17 Oct 2008 |
| 11005 |
24 (new cycle) |
N26E42 |
12 Oct 2008 |
| 11004 |
23 (old cycle) |
S08W17 |
11 Oct 2008 |
| 11003 |
23 (old cycle) |
S23E28 |
5 Oct 2008 |
| 11002 |
24 (new cycle) |
N25W27 |
23 Sep 2008 |
| 11001 |
23 (old cycle) |
N06E14 |
12 Sep 2008 |
| 11000 |
23 (old cycle) |
S13E24 |
19 Jul 2008 |
| 10999 |
23 (old cycle) |
S02E60 |
17 Jun 2008 |
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Data for the above table were obtained from the Solar Region Summary reports, provided by the Space Weather Prediction Center of the National Oceanic and Atmospheric Association (NOAA). As of December 8, no active regions have appeared since AR 11008. For an idea of how regions evolve, the region that became AR 11003 was first seen by SOHO/MDI on October 2. NOAA assigned a number to the region on October 5, when it was located at South 23, East (of the central Meridian) 28. On October 6, the region had decayed significantly, but the remnants could still be observed in H-alpha plage without spots.
Regarding the magnetic configuration of sunspots: Active regions in the northern hemisphere of the Sun that appear with negative polarity leading (toward the west), are a part of the new sunspot cycle of the Sun, cycle 24. (Click Sunspot Cycle for more information.)
New cycle spots in the southern hemisphere will appear with positive polarity on the western (right) side of the sunspot. On May 5, AR 10993, new cycle sunspots made an appearance in the southern hemisphere, where positive polarity leads. Compare AR10999 with the southern hemisphere new cycle spot of 6 May, 2008.
Regarding quiet-sun conditions: Since June 15, X-ray flux has been less than or equal to ~3 x 10-8 Watts/m2, with the exception of a B1.3 on February 10. Also, X-ray output increased with several B-class flares from November 2 through November 7. There were also several small flares from November 11 - November 13. The November dates correspond to the appearance of AR 11007 and AR 11008. Several B-class flares have accompanied AR 11009 on December 11. (See also GOES X rays on Solar Monitor).
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Click HERE for an animated gif movie showing ten days of solar (in)activity. Before September 22, the last numbered active region appeared on July 21 (AR 11000). Between June 11 - July 21, 2008, there were only two numbered active regions (AR 10999 on 06/27 and AR 10998 on 06/11). See the Solar Monitor or NOAA's Solar Region Summary Reports for more information.
Click HERE for an animated gif movie compiled from X-ray images spanning the period June 24 to July 8, 2008. The loops close to the equator on June 24-26 (to the right of the central meridian) are from old-cycle spots, NOAA active region 10999 (AR 10999). The Sun produced one B-class flare in the time period May 17 - July 11 (as seen by GOES ). For an explanation of flare classes, go to Space Weather's Classification of X-ray Solar Flares.
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