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Submitted on 2013-07-11
The plasmasphere is a region of "cold" (low-energetic) particles that extends from about 1600 km to over 30000 km above Earth's surface. It is an extension of the ionosphere, and overlaps the inner Van Allen radiation belt and a good part of the outer one. The difference between the plasmasphere and the Van Allen belts is that the latter contain "hot" (high-energetic) particles that behave according to a whole different set of rules.
Submitted on 2013-07-04
Last week, the remainder of a large sunspot complex rounded the west limb. For more than 2 weeks, it had dominated the outlook of the Sun. Initially consisting of 6 groups, only the two largest groups survived the transit over the solar disk. The graph underneath shows the daily sunspot number from 9 till 30 June as determined from SDO/HMI continuum images (1024x1024).
Submitted on 2013-06-25
During the early hours of 21 June, the relatively simple sunspot group NOAA 1777 unleashed a medium class solar flare. The M2.9 flare peaked at 03:14UT, and lasted for 73 minutes. Its x-ray signature clearly dominated the x-ray solar activity for that day.
Submitted on 2013-06-19
While last week was quite a bummer with respect to sunspot activity, the chromosphere offered a much more appealing view. Indeed, during a few days, various filaments of medium length were visible all over the solar surface, with one even attaining 400.000 km. These filaments can be seen in the Kanzelhöhe image underneath, taken on 12 June.
Submitted on 2013-05-29
A very impressive solar eruption took place on 22 May. Source region was the -at that time- not very impressive sunspot group NOAA 1745, near the northwest limb. The SDO-pictures underneath show the region at 15:00UT in white light and in EUV. From this relatively tiny sunspot, one would not expect so much ongoing flare activity.
Submitted on 2013-05-21
Early last week, the Sun produced 4 X-class solar flares in rapid succession. They all originated from NOAA 1748, a magnetically complex region located near the east solar limb. In summary, there was an X1.7 flare on 13 May peaking at 02:17UT, an X2.8 the same day at 16:05UT, an X3.2 early on 14 May at 01:11UT, and the final X1.2 on 15 May at 01:48UT. The SDO images underneath show for each flare the outlook of the region 1.5 hours before the maximum, the maximum itself, and 1.5 hours after the x-ray peak (resp. left, middle and right frame).
Submitted on 2013-05-17
This news item was written by Frederic Clette, WDC - Sunspot Index.
Many solar cycle predictions are based on mathematical or physical models. Current models are only able to produce a smooth global envelope to describe the variation of solar activity during one 11-year cycle, as illustrated in figure below. So, we are used to consider a solar cycle as a rather smooth bell-shaped curve with some asymmetry. This is definitely affecting the current interpretations of the rise of cycle 24.
Submitted on 2013-05-16
Solar observers were enchanted by a beautiful prominence appearance last week. The picture underneath was taken through a small 4cm H-alpha telescope on 9 May at 8:24UT, just hours before the prominence spectacularly erupted (movie).
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