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NOAA 1654 show-off


Active region NOAA 1654 appeared on 8 January at the northeast solar limb and quickly became the dominant sunspot group on the visible solar surface. On 11 January, its sunspot area equaled about 7 times the area of the Earth, and by 13 January its length was almost 19 Earth diameters. The leading spot was complex and changed its shape impressively, as can be seen in this movie covering the period from 10 January (noon) till 12 January (noon).

Sunspots galore


The SIDC sunspot bulletin for December 2012 reported a monthly provisional international sunspot number of only 40.8. That is the lowest since February 2012 (32.9). Solar flare activity was in proportion, with no medium flares (M-class) and several days with not even small flares (C-class).

A Christmas flare


July 2012 was one of the most active months so far this solar cycle, producing numerous medium and strong solar flares. Unfortunately, since then, solar flare activity has not been particularly exciting. In December, things went from bad to worse, with only a few dozen small ("C") flares and no medium ("M") flares at all. The previous month with no M-flares was December 2010. Also, the last M-flare dates back to 28 November 2012 (M2 in NOAA 1620), and the last extreme flare (X-class) occurred on 23 October 2012 (X1 in NOAA 1598). It seems ages ago!

The fairest of them all... (2012)


With 2012 nearing its end, it may be a good time to have a quick review of some of the more spectacular events that the Sun produced this year. Though Solar Cycle 24 (SC24) certainly has been weak so far, solar activity was quite interesting at times with the Sun producing some truly amazing events.

A sunspot square transits the solar disk


Sunspot groups come in a variety of shapes, and it is well known that such regions occasionally team up to form an eye-catching configuration. This was the case late November and the beginning of December, when NOAA 1623 and 1625 formed a nice square of sunspots.

Where's the coronal hole?


Coronal holes are regions in the hot solar atmosphere ("corona") where the plasma density of that temperature is very low compared to its surroundings, and thus they look like dark shapes in the corona. They are also known to be the source of the high-speed solar wind, and as such can create geomagnetic disturbances when aimed at the Earth. As the larger coronal holes may hold their shape through several solar rotations, they are interesting for long term space weather predictions.

Our dynamic Sun


Last week had a couple of days with increased solar activity. For the period of 20 to 23 November, 4 movies in as many different wavelengths were created showing some impressive dynamics in the Sun's atmosphere. Imagery for these clips was taken from the GONG/H-alpha Networkand from SDO/AIA and HMI.

The Sun has a split personality


Has SC24-maximum passed?


Once again, last week's activity was not particularly exciting: Just a few small single sunspots, that was it! Also, the SIDC announced that the provisional sunspot number for October was 53.3. That is the lowest since February this year. What a difference with the sunspot activity one year ago: Several groups dotted the solar surface during that November month, and also the biggest sunspot group so far this solar cycle (NOAA 1339) made its appearance. Obviously, one wonders if SC24-maximum has already passed.

15 X-flares for SC24


On October 23, active region NOAA1598 produced the 15th X-class flare of the current solar cycle (SC). The X1.8 was of short duration, lasting only 8 minutes. It did not produce an energetic particle event (proton event), and there was no obvious indication of an ejected plasma cloud.

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