news
Submitted on 2015-07-08On 1 July 2015, the revised sunspot number (SN) was introduced by the World Data Center SILSO (see this press item). This "Version 2.0" obviously affects the maximum and minimum values of each solar cycle (SC), as well as some of the related timings, i.e. the time it takes for solar activity to rise from minimum to maximum (Trise), and back to the next minimum (Tfall).
Submitted on 2015-06-24Proton events have already been discussed in earlier news items, such as on 23 January 2014 and on 16 August 2012. It concerns solar eruptions associated with a strong increase in the flux of particles with energies of 10 MeV or more (Note 1). Once this proton flux exceeds the pre-established threshold of 10 pfu (Note 2), it is considered a proton event, if not it is labeled a proton flux enhancement.
Submitted on 2015-06-09
| A very nice filament eruption occurred near the north-western solar limb during the morning hours of 3 June 2015. It concerned the long filament already mentioned in the previous news item of 27 May 2015, when it was still in the north-eastern quadrant. |
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Submitted on 2015-05-27Last week, the sunspot activity was again all but exciting. Only a few, very small, and mostly inactive sunspot groups were visible in white light. In H-alpha, which is a filter showing the "cold" inner atmosphere of the Sun, the Sun's outlook was dominated by some long filaments. These are local belts of plasma squeezed together by opposite polarity magnetic fields (see last week's newsletter). Moving up to the hot outer solar atmosphere, the extreme ultraviolet (EUV) imagery from SDO showed darkish patches.
Submitted on 2015-05-20Some very nice prominence and filament eruptions were observed over the last week. In this MOVIE, four major events are shown in the combined filters of SDO's AIA 304 ("cool"; about 80.000 degrees; red) and AIA 193 ("hot"; about 1.3 million degrees; green). Prominences and filaments usually lay dormant until the surrounding magnetic fields become unstable and eject the material into space.
Submitted on 2015-05-06The STEREO spacecraft are still in safe mode as they go through their superior conjunction, passing behind the Sun as seen from Earth. This means that for an extended period of time, we cannot receive any imagery from the far-side of the Sun due to radio interference from the Sun. See the STEREO-website for up-to-date information.
Submitted on 2015-04-30
Squeezed between magnetic fields of opposite polarity, a really big blob of plasma (charged particles) rounded the Sun's northeast limb. The prominence offered impressive sights in H-alpha filters, which are suited to observe the inner, "cold" (10.000 degrees) atmosphere of the Sun.
Submitted on 2015-04-15
At the end of a rather dull week, a cluster of sunspots appeared from behind the northeast limb. The active region was numbered NOAA 2321, had a sunspot area of about 4 times the surface area of the Earth, and produced an M1 flare on 12 April.
Submitted on 2015-04-09
In absence of any large or complex sunspot group, this week's main event was another spectacular filament eruption. This eruption took place late on 4 April and was associated with a long duration C3.8 double ribbon flare that started at 22:16UT, peaked at 00:07UT, and ended at 01:45UT. "Double ribbon" here means that there are two bright ribbons parallel and along the location of the ejected filament.
Submitted on 2015-04-02
Around noon on 27 March, a giant wall of solar plasma (charged particles) propelled itself into space. A movie of this event can be seen here.
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