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31 January 12 - Flare Forecast Evaluation - On a daily basis, NOAA/SWPC and SIDC predict the likelihood on solar flares. A crude evaluation of the confidence one can have in these predictions, is to bin the probabilities in "< 50%" and "> 50%" and compare them with the actual (non)-occurence of these flares for that particular day (0 or 1). Based on NOAA's RSGA and SIDC's Daily Bulletins, a comparison was made for 2011. The results for M-flare prediction are shown underneath.

As can be noted, SIDC performs a few % better than NOAA (87% vs. 83%; green columns), but it must be taken into account that SIDC makes its prediction at noon, and NOAA 12 hours earlier. A fair comparison would thus require for SIDC to regroup the flare occurence from noon till noon of the next day. Both organizations have the same error rate (about 8-9%; red column), error meaning here not having predicted days with at least 1 M-flare. Note these M-flares include filament eruptions like on 7 June 11, or beyond/near the limb events like on 28 January. Nonetheless, SIDC really seems to be better when it comes to avoiding false calls (no eruption when one is predicted; orange column): When SIDC has a > 50% probability on M-flares, they are correct in almost two thirds of the cases. For NOAA, this is only fifty-fifty.

Obviously, the study can also be performed for C-flares, but NOAA has no probabilities for this class and thus no reliable comparison is possible. It's interesting to note that neither NOAA nor SIDC had a day with > 50% probability on X-class flares, meaning all of the 8 X-flares in 2011 were missed. If one assumes this is a difficulty in estimating the strength of the potential flare, and thus allowing that a > 50% probability on M-flares includes also the X-class, then SIDC outperforms NOAA 7 to 5.

28 January 12 - Yesterday, NOAA 1402 sent us a departing shot (movie from galaxy387 and Solarwatcher) while rounding the western solar limb: An X1,7-flare peaking at 18:37UT. That NOAA 1402 produced another flare was not such a surprise: the group seemed to be decaying, and the restructuring magnetic fields then sometimes produce flares. What was not anticipated (NOAA, SIDC), was that this flare made it all the way into the highest X-ray class. Except for the x-ray radiation and the proton event (about 800 pfu (S2) at the moment), Earth will not be influenced by this event. Indeed, the spectacular CME seems to be directed completely away from us. The STEREO-satellites now have the best view on the further evolution of this "bad boy".

23 January 12 - Early this morning, NOAA 1402 produced an M8,7-flare. The eruption occured in the same area (i.e. along the same inversion line; see before and during the flare) as the M3-flare from 19 January (GONG H-alpha).
The flare has sent a complex, fast-moving CME (STEREO Behind) towards the Earth that could produce a geomagnetic disturbance on 24 January.
There is also a strong proton-event (S3-radiation storm; see NOAA-scales for risk) in progress. Its level is actually topping 3000 pfu, which makes it the strongest event so far in SC24 and the strongest since May 2005 (see NOAA/SWPC list). The protons are visible in SOHO's LASCO-images (also at Spaceweather).

The website of the SIDC has a great overview of the recent events on the Sun and near Earth, as well as a nice SDO-movie. Some great YouTube movies also by Solarham.com, VIDEOVAX, this one, and another Solarham.com containing a GOES-15's SXI-clip. The latest SXI-images show the development of a new cusp, and the latest GONG-movies show there's still some filamentary structure present...

20 January 12 - A beautiful long-duration M3-flare erupted yesterday along the magnetic inversion line near region 1402. An inversion line separates regions of opposite magnetic polarity and was in this case clearly defined by a fine, right-angled filament "left" from the main spot (see GONG H-alpha images underneath, taken at resp. 11:00UT, 15:15UT and 19:00UT).
As the filament was ejected, hot regions came into existence in the area where magnetic field lines reconnected (visible at the top of the coronal loops in these YouTube-movies AIA171 and AIA304) and on the solar surface where some material rained down (GONG-images underneath). This gave a complex evolution of the hot parts of this flare, at times making it look like a candle flame (upper right image; SDO at 16:00UT).
This shape makes one think of cusps (image lower right; Yohkoh-image from 07 June 2000). UPDATE: Initially I thought this was not a cusp, because today's structure seemed to be built up of several fine coronal loops, whereas a cusp is really a solid shape filled with plasma from the eruption (more on cusps at Yohkoh's "Science nuggets" via "Hot Topics"/LMSAL). However, the x-ray-images (just like Yohkoh's, not EUV like SDO's) of GOES-15's SXI show much better the cusp-like features of this post flare structure. See for example this SXI-image made 20 January at 23:56UT.
Also impressive are the highly helical dynamics of the ejected filament material, as can be seen in this multicolor movie made by SDO (Solarsoft). Initial analysis (SIDC, NOAA) indicates Earth may be hit by the CME late on 21 January. The flare also enhanced proton levels, but the treshold has not been reached. (updated at 21 January at 13:00UT).
The southern part of the region's filament was not ejected. Moreover, the rest of the filament seems to be reshaping itself (see latest GONG-images). Hence, more energetic flares may be produced in the coming days and these may again be Earth directed as NOAA 1402 transits the central solar meridian.

UPDATE: I added another movie on YouTube, this time combining SDO-images in the wavelengths of 4500Å (photosphere; 6000K), 171Å (upper transition region; 650000K) and 335Å (lower corona; 2,5 million K). This clip shows well the position of the eruption and the post coronal loops relative to NOAA 1402's main spot. Note how one end of these loops seems to be anchored above the region's main (big) spot. The movie is best viewed in half-screen or at the website of Helioviewer (link in description box).

04 January 12 - I've uploaded 2 more movies on YouTube:

• The sunspotgroups of 2011 (uploaded 04 January 2012)
• NOAA 1380 or 1387? (uploaded 28 December 2011)

Additional details are in the movie's description box.

25 December 11 - There has been quite some solar activity over the last 48 hours, in particular some really great prominence and filament eruptions. Based on images from the SDO-satellite and the GONG H-alpha Network, I've created 2 YouTube-movies showing the events in the red 304A and in H-alpha. Comments were added to the videos. The H-alpha movie does not cover the third event (24 December prominence eruption at the NW-solar edge) due to a rare gap in the H-alpha series, but its evolution was nicely captured by Guido Gubbels from the Belgian Solar Section. Update: Beautiful movie of the same event by Rogerio Marcon.

03 December 11 - The provisional SIDC SSN for November is 96,7. This continues the positive trend in solar activity that started this summer. As can be seen from an earlier statistical prediction, these values are within line for a moderate maximum SSN of 83. Because this maximum is expected to be still a few months out (second half of 2012 at the earliest), it is expected the maximum will rather be in the upper half of the uncertainty band (so between 83 and 101). This is also in line with earlier predictions by the NASA/NOAA WG (90 +/- 20). Certainly no Dalton-minimum is in the offing.

Graph underneath also shows the increase in medium (M) and strong (X) solar flares. So far, there have been 126 M- and 8 X-flares for SC24, with the majority produced over the last few months. The table shows the most flare-prone sunspot groups, ranked according to the total fluence (power of the flares). For a predicted SC24-maximum of 83, over 700 M-flares and about 100 X-flares can be expected. There have also been 8 small proton flares so far. The last one was produced on 26 November and had a geometry very similar to another (non-proton) event on 30 November. See the GONG-website for H-alpha movies of these events (resp. Udaipur, Big Bear).

The increased solar activity also brought us the first 2 supergroups of SC24 (see my 2004-research for more info on big, super and giant sunspot groups). Some characteristics and images of these groups and the 3 big groups can be found in table underneath. No giant groups so far, but even for this moderate cycle a few can be expected.

More on sunspot generation, sunspot activity prediction, and the current state-of-affairs in SC24 can be found in the presentation I gave last week om MIRA Public Observatory. Please allow some time for upload, as the presentation is about 30MB, and the accompanying zip-file with all the movies is 533MB. Thanks to Philippe Mollet for hosting these files on his website.

15 October 11 - Applying the McIntosh-classification on sunspotgroups - There were quite a few sunspotgroups visible today. Using the McIntosh-classification, one might get an idea of the flare-production in the next 24 or 48 hours. Experienced organizations like NOAA or STAR provide on a daily basis the classification of the visible sunspotgroups, thus giving an idea to the solar and spaceweather community on the imminent solar activity for that day. However, for many years now, NOAA is known to make blatant errors in their classification. STAR provided a welcome check on the NOAA reports, until they started using the very big SDO-images (4096 and 2048). Not only the classifications are indicating too much activity, groups which are too small (actually pores) are also counted into the sunspotnumber.

As an example, NOAA and STAR-classifications (both made about 8 hours before my own) were put together unto one map with my visual observations (Celestron 8", 68x, Thousand Oaks ObF, blue OcF). The map used is the 512 SDO-image just a few minutes before my own observation, and represents very well what I saw with reasonable seeing (see image with the classifications above). 3 small groups that were only seen by STAR (2 near NOAA 1319 and one near NOAA 1309) were not indicated on the map, to avoid overflow.

As one can see, major differences exist in NOAA 1312, 1313, 1316 and 1319.

• For NOAA 1312, one could be forgiven to classify this group as Hsx, because the North-South-diameter is barely 2,5° (see Solar Monitor). STAR's Dko is flat wrong, faulty influenced by the moving magnetic fields which seem to suggest bipolarity in the main spot. I want to emphasize that McIntosh-classifications are done solely on visual observations, without the support of e.g. magnetograms.
• For NOAA 1313, it is beyond me how NOAA sees a penumbral spot near the main spot (required to have a D-type spot). I doubted to make this a Hrx, but the penumbra around the umbra was quite well visible (better than in this SDO-image).
• For NOAA 1316, I would recommend both NOAA and STAR to reread Patrick McIntosh's article on the sunspot classification. In this case we have 2 distinct portions, and thus an open sunspotgroup. The trailing spot is the biggest one, but smaller than the one in NOAA 1312 (hence "s" and not "h"). It is slightly asymmetrical, but not enough to classify this as an "a" (or "k") spot.
• Finally, NOAA 1319 simply does not contain a single spot with a mature penumbra. Mature spots can be found in the principal spots of NOAA 1316 or 1317. Aside the visual observation, it should be noted that there is some mixed magnetic polarity in the middle portion, however right now it still concerns small spots. Thus, flares are expected to be in the C-class only.

Because of this overestimation of the sunspot-classification, this also gives a wrong idea of the possible solar flare acivity. Table underneath gives for today and for NOAA, STAR and myself the number of groups, the sunspotnumber (SSN), the Classification Value (Malde) and the expected number of M- and X-flares according to Kildahl (Bornmann and Shaw). So, I predict for today just a few C-flares from the main regions, with only a remote chance on an M-flare. NOAA expects for today 1 M-flare (with a remote chance on zero or two M-flares), and STAR expects between 1 and 3 M-flares.

01 October 11 - Between 08:00 and 10:00UT this morning, some interesting solar activity could be observed in Ha. The first hour, a few prominence eruptions and surges took place at the northwestern limb near NOAA 1301. This sunspotgroup was either spotless (bright faculae field) or located behind the limb, and the activity did not leave much of an X-ray signature. Meanwhile, some restructuring was taking place in the northern filament portion of NOAA 1302. This resulted at around 09:00UT in a dark filament eruption and surge, followed by a C2,7-flare (maximum at 09:10UT). The expulsed material could be seen flying over the sun's limb starting around 09:25UT, with the brightest parts remaining visible in Ha until 09:46UT at an est. 140000 km above the solar limb. This CME came after some material ejected by another surge in NOAA 1301 at 09:20UT. They could be distinguished from each other by the slightly different ejection angle, and NOAA 1302's was a little wider. Meanwhile, an eruption was already taking place in the northern part of NOAA 1305, peaking at 09:39UT (C5.9). It was followed by an M1,2-eruption (1B) in the southern part of this sunspot region peaking at 11:59UT. The maximum brightness in H-alpha was reached well in advance of this maximum X-ray brightness (11 minutes). In the movie from the GONG Ha-Network, a Moreton wave can be seen heading southward. It seems the wave originated during the transition from the northern to the southern flare-phase.

The image underneath shows the solar surface and surroundings at 09:29UT as could be observed in 30.4 nm (SDO) and in Ha (GONG/El Teide). It shows the

The X-ray-evolution of these events can be seen in the GOES15-X-ray-image underneath. As could be expected, NOAA considered the three eruptions as 1 event, which probably is OK for the two eruptions in NOAA 1305, but certainly not for the preceding event in NOAA 1302.

245 September 11 - In view of this month's flurry of high-energetic solar flares, table underneath summarizes the Top-10 11 12 13 of the most powerful flares during Solar Cycle 24 so far. The flares are ranked according to their peak X-ray strength. The list was compiled from SIDC-reports, the daily SWPC-summaries and NOAA's "The Weekly". Please consult these documents for further information on the parameters used. Images and movies can be found on Spaceweather.com, GONG H-alpha Network, SDO and SOHO.

NOAA 1302 is visible with the naked eye and the biggest sunspotgroup of SC24 so far. With its mixed magnetic polarities in the middle portion, it continues to be a potential source of high-energetic flares. As NOAA 1302 rotates further on to the solar disk, its eruptions may become more geo-effective.

23 September 11 - Some results of research in the domains of solar physics and geomagnetism: Ultrafast substorms explained, The secret lives of solar flares (also at Sky&Telescope), New method detects sunspotgroups before they are visible (also at PhysOrg_com), Wave power can drive sun's intense heat.

10 September 11 - The Solar Cycle 24 Tracking Page and the page with the most energetic flares since 1976 have been updated.

08 September 11 - From 19 to 23 September 2011, a very important meeting on the calibration of the sunspotnumber will take place at Sunspot, New Mexico, USA. Today's heavyweights in the observation and determining of the sunspotnumber will discuss a variety of topics in order to get numbers that are truly and reliably comparable on the timescale of several hundreds of years. The issue was summarized very well by Leif Svalgaard in his 06 July talk in Melbourne, Australia. Aside Leif, the workshop will also be attended by Ken Schatten, Frederic Clette, Peter Foukal, Thomas Friedli, David Hathaway and Bill Livingston, amongst prominent others. The program can be found here. A follow-up workshop is planned in Europe next year. Needless to say a lot of work is going to be involved in this, but the potential outcome might have far-reaching consequences in all areas related to the observing of sunspots and the determining of the sunspotnumber. To be continued!...

07 September 11 - Yesterday morning at 01:50UT, NOAA 1283 produced a high-energetic M5,3-flare (H-alpha class 1B). At 22:20UT, it produced an even more powerful X2,1-flare (2B). Both flares resulted in a proton enhancement, but the event treshold was not reached. NOAA 1283 is not a big group, but it does have opposite magnetic polarity spots close to each other. At this moment, this configuration is still there, but the spots are more separated from each other. Major flares remain possible. SIDC reported each flare was associated with a halo CME. However, since they are both directed north of the ecliptic plane, only a glancing blow is expected and not before midday of 09 September. Movies of the events can be found at Solarsoft and GONG H-alpha Network (Mauna Loa "Mh"; see image underneath).

05 September 11 - The Spotless Days Page was updated. There have been 817 spotless days so far, with 14 August 2011 the most recent one (preliminary SIDC-report for August). This is not an unusual occurence at this stage of a moderate to low-amplitude solar cycle.

Lately, there has been some interesting activity from NOAA 1280 at the northwestern solar limb. The region developed quickly since saturday (SDO, Solar Monitor), and a Mount Wilson drawing (03 Sep 11) showed opposite magnetic polarity spots in close proximity of each other (mind foreshortening effect!). Several M-flares were the result as the group started its backside transit. Fortunately, we have STEREO to follow its activity. A case of "What goes around, comes around..."?

Courtesy of the SDO(NASA) and the HMI Consortium, and the Kanzelhöhe Solar Observatory (CESAR).
Delicate coronal loops can be seen hovering over the flaring region in AIA171 (left) and H-alpha (right) at 07:08UT.

19 August 11 - Stereo-A tracks December 2008 Coronal Mass Ejection from Sun all the way to the Earth - Some very nice movies on how a CME evolves on its way from the Sun to the Earth are provided by Stereo-A. This satellite was about 45° ahead of the Earth and thus had a really good view of the Sun-Earth line at that time. An explaining clip by GSFC can be found underneath and more movies describe the details of the entire happening (WUWT, Science-at-Nasa, Universe Today). Though it is certainly not the first time the Stereo-satellites tracked CME's from the Sun to the Earth (see Stereo panorama, CME has croissant shape and RAS), it's the new image processing technique that provides unprecedented views of the evolving CME on its route to Earth.

Courtesy of NASA/GSFC

09 August 11 - X6,9-flare in NOAA 1263 - Earlier this morning, the strongest solar flare so far in SC24 took place in NOAA 1263. The explosion occured at 08:05UT near the "middle" portion of this complex group, where negative magnetic polarity from a new region met the positive polarity of the trailing spots of the original NOAA 1263. This location caught the immediate attention already 2 days ago, when the two fluxes bumped into each other. Initially, black polarity was to the north of the trailing spot, and did not give rise to much flare activity as the spots remained a bit separated from each other. Yesterday, black polarity also engulfed the southern portion of the trailing spot, producing an M3,5-flare (with proton-enhancement) at 18:10UT yesterday evening and a M2,5-flare at 03:54UT earlier this morning. Both events occured on the southside of the "middle" spot and got H-alpha class 1B. The X6,9-flare covered the entire area (H-alpha class "3B" from my own observations; 2B according to NOAA), so both north and south of the trailing spot (see images underneath from SDO (visual and magnetograms) and the GONG H-alpha Network). The event is also a proton-flare and still in progress. The most recent SDO-movies show the opposite polarity spots are still very close to each other. Further energetic events remain possible.

Courtesy of the SDO(NASA) and the HMI Consortium, and the NSO/GONG H-alpha Network Monitor

07 August 11 - There exists a real possibility on a major eruption in NOAA 1263 as the leading portion (negative "black" magnetic polarity) of a newly developing region is bumping into the trailing portion (positive "white" polarity) of the original NOAA 1263. If the spots come within less than 2,5° of each other (and are strong enough), an M- or even low X-flare could be produced in the next 24 hours. There is no reason to classify these regions (NOAA 1263 and the "new" region) separately, as they are within less than 10 degrees in longitude of each other. It's good to know though what's going on, so that the possibility on a major eruption can well be estimated. Movies at Spaceweather.com and SDO (magnetogram).

06 August 11 - Update on geomagnetic storm - The geomagnetic storm seems to be gradually subsiding. Maximum Kp of 8 was reached yesterday during the 18:00-21:00UT interval. Per subsequent 3-hour-interval, Kp then went down by 1 point. The latest geophysical alert message from NOAA/SWPC states the storm reached G3-levels (NOAA-scales). According to Spaceweather.com, aurorae were seen in Europe as far south as England, nothern Germany, Poland and the Netherlands, and for the United States Colorado and Nebraska. NOAA's latest Report of Solar-Geophysical Activity merits close reading (my comments are highlighted):

The last similar geomagnetic storms date already back from 05 April 2010 (Combination of NOAA 1059 and coronal hole; Kp "only" 7) and then already from 14-15 December 2006 (NOAA 0930; Kp-index of 8 for 9 hours!). A Kp-index of 9 dates already back from 11 September 2005 (NOAA 0808). With its geomagnetic latitude of 45°, this is in principle the Kp-value needed for aurorae being visible from Belgium.

05 August 11 - Major geomagnetic storm in progress - The second CME passed ACE at around 17:00UT this afternoon, and started to influence the geomagnetic environment shortly before 18:00UT. Solar wind speed jumped from 400 to 600 km/s. Similar to the first CME (which arrived yesterday evening around 22:00UT), this is a considerable slow-down compared to its solar lift-off speed of over 1100 km/s. However, this time the impact is much more pronounced as Bz (the vertical component of the interplanetary magnetic field) turned strongly southward. With currently sustained levels of -20 nT, this is indeed twice yesterday's value. The Kp-index for the period 18:00-21:00UT was 8, which corresponds to a severe storm (G2 or possibly G3: see geomagnetic NOAA-scale for effects). Auroral activity, as measured by POES, continues to increase as Bz has remained strongly negative over the last two hours. Over the last hour (21:00-22:00UT), the auroral activity level jumped from 6 to 10. Weather permitting and if Bz remains southwardly oriented, aurorae could be visible down to northern England. Spaceweather.com also reports that the CME has pushed the magnetopause close to geosynchronous orbits, thus exposing satellites at these heights directly to the solar wind.

Earth's space environment can be monitored on ACE and at SWPC.

As modellers from the GSFC Space Weather Lab have been calculating, it is very likely this CME is the combination of the CME's from 03 and 04 August. Solar wind data will provide the answer in the next couple of hours.

04 August 11 - In view of the ongoing solar activity, table underneath summarizes for each of the 3 big groups per day their McIntosh-classification, the number of C- and M-flares and the strength of the strongest flare produced (See this presentation for the different types of solar flares). The McIntosh-classification was determined using HMI-Intensitygrams (1024-resolution) taken by SDO, usually at around 05:50UT that day. The flare-data are from NOAA/SWPC's "Event reports". Today's flare numbers are still preliminary.

As the SIDC pointed out in their latest Presto Alert, the energy of the NOAA 1261 eruptions seems to be increasing. This is not only visible in the flare strength (M1, M6 and M9 on resp. 2, 3 and 4 August), but also in the speed of the CME's (resp. about 800, 1100 and 1200 km/s) and the increase in proton level (after 2 proton "enhancements", the M9-flare produced a proton event, probably also because the region is now more westward). In view of today's simplified structure of the group, even more energetic events are not expected.

The CME's are expected to reach Earth late 04 or early 05 August. In view of the speed differences, it is not unlikely that the CME of the latest M9-flare will catch up with the CME's of the earlier two CME's before they reach Earth, which might lead to a complex and -pending the north-south magnetic orientation of the CME- severe geomagnetic disturbance. Because in each of the three flares, north (white; "coming out") was on top of south (black; "going in") polarity spots, it is not unlikely that this orientation is also embedded in the CME's, thus favoring a north-south ("negative") orientation, hence severe geomagnetic disturbances. Earth's space environment can be monitored on ACE and at SWPC.

Finally, as the three regions approach the western solar limb, and if they continue to show flaring activity, it is very well possible to get some really spectacular prominence eruptions in the next few days.

01 August 11 - With the preliminary SIDC-sunspotnumbers and the improved Bendel-Staps SSN25-formula, one can calculate a new value for the SC24-amplitude. The preliminary smoothed sunspotnumber (SSN) for January 2011 being 30,27, a SC24-maximum of 83 +/- 18 is predicted. This is slightly up from an earlier prediction (78 +/- 20) based on the rate of increase 19-20 months after solar cycle minimum (see Headline of 05 March 11).

Figure underneath shows the monthly sunspotnumbers (SIDC) and the predicted values based on R_max = 83, and an uncertainty of 18. The curves were calculated using Hathaway's method. The obtained values again seem to exclude Dalton-like or average amplitudes. Rather, they seem to hint to a maximum similar to those in the late 19th - early 20th century (SC12, 13). The maximum is expected in May 2013, with an uncertainty of 10 months.

A word of caution: This is a statistical approach, meaning that uncertainties both in amplitude and in timing can deviate significantly from the predicted values, even at this stage of the cycle!

The next key-moment in this statistical follow-up of the evolution of SC24 will be when the smoothed SSN reaches 50. According to the Waldmeier laws, this happens about 23 months (+/- 8 months) before the SC reaches its maximum. In view of the monthly sunspotnumbers we had lately, this could be happening right now... More early next year, when the smoothed numbers will come in.

01 August 11 - Triumvirate of major sunspotgroups rules the (northern) solar surface, as can be seen in the images underneath. The visual image and magnetogram were taken by SDO at 06:40UT this morning, the H-alpha image is from the Learmonth Observatory, Australia taken only 20 minutes later. Most flaring activity comes from NOAA 1261 (middle). That's certainly not the biggest group, but over the last few days, it has developed some magnetic intermixing with opposite magnetic polarity spots close to each other. This is not the case for big group 1263 (opposite fields with almost no such closely spaced spots) and quiet NOAA 1260 (right), which is just an open group without any magnetic intermixing at all. This difference can also be seen in H-alpha: NOAA 1261 is a lot brighter than NOAA 1263, whereas NOAA 1260 is not bright at all. Based on these observations, small M-flares from NOAA 1261 remain possible. NOAA 1263 has an outside chance in producing an M-flare, and NOAA 1260 has the potential for C-flares only. Using eclipse glasses, both NOAA 1261 and 1263 were naked eye objects this morning.

27 July 11 - At last... some solar activity! Around 16:00UT this evening, NOAA 1260 has produced an M1-flare. Though consisting of only small spots, it has some magnetic polarity mixing which may herald further flare activity. NOAA 1261, despite being larger, has no such mixing and is -at this moment- very quiet. Live evolution of the flare activity can be followed at GONG (H-alpha), SWPC (X-ray) and SDO (visible and other wavelengths).

16 June 11 - Significant findings in solar research - Over the last couple of weeks, some interesting scientific results in the domain of solar research have been announced. An overview.

• Heliosphere
• 09 Jun 11 - Voyager spacecraft detect magnetic foam zone at the edge of our solar system (Science at Nasa, PhysOrg.com)
• 15 Jun 11 - Voyager 1 is nearing the heliopause (PhysOrg.com, Universe Today)
• Solar activity heading for hibernation?
• 14 Jun 11 - Sun's fading spots signal big drop in solar activity (Livingston, Penn, Svalgard) (Poster, Abstract, WUWT)
• 14 Jun 11 - Missing Jetstream indicating a delayed or missing solar cycle 25 (Hill, Howe, Komm, et al.) (Abstract, WUWT)
• 14 Jun 11 - "Crawl to the Poles" of coronal emission features indicates delayed SC24-maximum (Altrock) (2010-Paper, Universe Today)
• New insights on how solar minimums might affect Earth (PhysOrg.com, discussion at WUWT)
• Solar corona and flares
  • 15 Jun 11 - SDO detects superfast solar waves (PhysOrg.com)
  • 15 Jun 11 - Solar magnetic ropes cause giant solar eruptions (SDO, PhysOrg.com, discussion at WUWT)
  • 14 Jun 11 - STEREO sees complete far side of the Sun (PhysOrg.com)
  • 07 Jun 11 - Surfing waves responsible for coronal heating? (SDO, Nasa's GSFC)

07 June 11 - At around 6 o'clock this morning, magnetic fields in NOAA 1226 became unstable and resulted in a medium M2,5-flare accompanied bij a spectacular CME and a still ongoing protonstorm. As usual, the event was captured in its entirety by SDO (See Spaceweather and SolarSoft for some stunning movies). Certainly watch the "difference-movies" showing how the CME is actually perforating the magnetic bubble around the blast side! It is clear, also from SOHO's Lasco-movies, that (the central) part of the CME is ejected. However, another part of the CME is falling back over an unusually wide area along the magnetic field lines to the solar surface as in a round fountain (dark material in the AIA-movies), and in some places causes a modest brightening (see Science-at-Nasa for more peculiarities on plasma rain).

The Sun Today made some very useful commentaries to what there actually can be seen (see movie underneath).

The spectacular event was also observed by Proba2 (SWAP) in EUV, and also by the GONG-network that caught the entire event... in H-alpha. In particular today's Udaipur-H-alpha movie is really fascinating! Also Cesar had a good look on the flare.

The SIDC's assessment indicates a CME-speed of 1000 km/s, and expects -in view of the large spatial extent- a geomagnetic disturbance on June, 9th. The severity of the impact will depend on the north-south-orientation of the arriving particle cloud.

Finally, it is to be noted that today's blast originated in the same area as the June, 1st C4-flare. That event was also accompanied by a CME that -together with a similar event in NOAA 1227 on June, 2nd- caused geomagnetic disturbances on 04-05 June with aurorae visible in Canada and northern US.

UPDATE - Some magnificent movies of this event were uploaded at NASA's Multimedia Videogallery (movies from 01 and 11 July 11).

Courtesy of The Sun Today

02 June 11 - The filament complex currently showing in the northern hemisphere looks a lot like the one late july 2010 that caused an impressive "global" eruption on the sun. It's actually not too far from the same location too (only about 40-60° more to the east). Interesting to see what's going to happen this time.

Meanwhile, the filament in between NOAA 1227 and 1226 that disappeared after today's spectacular eruption (C3-flare with H-alpha class 2N!), is starting to reestablish itself. Magnetograms show NOAA 1227 is not a bipolar group, but 2 separate groups. Of course, visual observations prevail! NOAA 1226 is currently a loose pile of sunspots. At the moment, it seems to have gained some more sunspots and area coverage. Also curious here to see how that one is going to evolve: 1 complex group or 2 separate groups (or maybe both...)?

29 April 11 - In view of the sudden increase in sunspotnumber as observed during the month of March 2011, I added an article to the Solar Cycle Page entitled "Extreme changes and quiet spells in monthly sunspotnumbers". As can already be seen in the graph underneath, the March-increase was important, but -for the same sunspotnumber- more important increases have been seen in the past.

21 March 11 - There's currently a proton enhancement ongoing, without any noticeable flare of filament eruption preceding it. It also got nothing to do with the impressive prominence that was visible at the southwestern solar limb last saturday. From today's SIDC-bulletin:

The proton flux measured by GOES13 increased this morning. The storm threshold is not reached. We don't expect the threshold to be passed. A back sided plasma cloud came into view of STEREO B COR2 at 02:54UT, March 21, 2011. This CME is probably associated with the increased proton levels. The Earth is magnetically connected with the source site behind the Sun. The Parker spiral has bended magnetic field lines that guide the electrically charged protons. The Earth is near such field lines along which these protons travel. This is a rare event.

UPDATE: A long duration C-flare took place on March 21. The source region is located in the west: Cat 35/AR 1176. A CME was ejected. The CME is not earth directed. We expect more flaring activity from this group. This event probably pushed the >=10 MeV proton flux to a higher level, the curve passed slightly and for only a short time the storm threshold. The flux level is at the moment still elevated.

The Stereo A-movie (04:00UT) seems to show coronal loops forming above NOAA-region 1169, which was also at the origin of a mild proton enhanced event last week, followed by the flare/CME as can be seen in the Stereo B-movie. Really amazing how a region at the sun's backside can still significantly affect earth's spaceweather. For the Stereo B-event to have any influence on the proton flux, it would require a very special Parker spiral shape though.

Meanwhile, old active regions 1164 (N) and 1165 (S) are about to cross the eastern limb for a "rerun". GOES- and SDO-imagery seem to indicate that these regions are still bright and active, showing large coronal loops. They merit close monitoring.

17 March 11 - Very nice movies of yesterday's long duration (5h32m!) C3-flare in NOAA1169, which produced an impressive CME and mild proton enhancement, can be found at Spaceweather, Solarsoft, SolarCycle24.com (1, 2), NSO, or you can create your own movies at SDO (time frame suggestion from yesterday noon till today noon) or at SOHO's Movie Theater. A slight coronal disturbance, probably due to magnetic restructuring above NOAA1169, can be seen just before the flare and beautiful coronal loops set in.

10 March 11 - The sun strikes again! - Only a few weeks after having unleashed the first X-class flare of SC24, the Sun produced an impulsive (short-lived) X1,5-flare on 09 March peaking at 23:23UT. Originating in complex region NOAA 1166, movies of the event clearly show the eruption was preceded by a disappearing filament near region 1169. This disappearance was probably the consequence of the C9,4-flare about an hour earlier in the trailing part of NOAA 1166.

Cut-outs underneath (running difference from AIA304Å movie) show the action in and around NOAA1166 and 1169. The first and second image show the plasma moving back in a very fine tube (indicated by parallel arrow) towards NOAA 1166. The crashing into the trailing part of NOAA 1166 may have caused additional magnetic instability and subsequent eruption in the middle portion of the group. The 3rd image show the beginning of the disappearing filament near NOAA 1169, while the 4th image adds the flare in region 1166. The last image shows the remainder of the erupted filament drifting by north-east of the fading blast site. Spaceweather.com has stated that the SOHO's C2-images show no signs of a bright CME (my emphasis).

Screen-shots from the SDO/AIA 304Å-movie (running difference) of the event in and around NOAA regions 1166 and 1169.
Courtesy of SDO (NASA) and the AIA consortium

To really appreciate the complexity of the events, one has to take into account the must-see H-alpha movies made by Thomas Ashcraft.

• T. Ashcraft - 21:46-22:17UT - C9,4-flare (so even before the disappearing filament in NOAA 1169!)
• T. Ashcraft - 22:19-22:53UT - Subsequent H-alpha activity in NOAA 1166, with impressive surge/CME east of NOAA 1166.
• SDO/AIA304Å - 20:00-23:00UT - SDO-movie of the foregoing events. Spaceweather.com incorrectly attributes the CME/surge to the X1,5-flare, but when one uses the SDO movie-tool to recreate the AIA304Å-sequence, the CME corresponds to the 22:44UT-image, well before the onset of the X1,5-flare!
• SDO/AIA304Å - 22:45-23:49UT - Running difference of the SDO/AIA304Å-movie with disappearing filament and X1,5-flare as described before. I would not exclude the possibility that the disappearing filament has nothing to do with NOAA 1169, but is actually the remainder of the CME/surge from the C9,4-flare!
• T. Ashcraft - 23:05-23:26UT - X1,5-flare itself ("2B" in H-alpha flare classification).

One can also consult the H-alpha movies made at NSO or BBSO. The combination of these truly impressive movies and animations do justice to the complexity of this remarkable chain of events.

07 March 11 - UPDATE: Eruption of NOAA 1164's canopy - Around 20:00UT this evening, the arches hovering over NOAA 1164 have become instable and erupted. This resulted in a M3,7-flare (20:12UT) as can be seen in this SDO/AIA304Å-movie, showing plasma raining down on the much denser inner solar atmosphere. See the LMSAL Solarsoft website for movies of the entire event. The stunning images underneath are screenshots from these movies (notice 3 different events, to show today's changes in the canopy), and the overall solar image comes from the SDO-website (AIA304Å, 19:59UT). This event is entirely different from today's M2-CME-event in NOAA 1166.

Update: A proton event is still in progress. The CME had the impressive speed of 2200 km/s (Spaceweather.com, NRL). As predicted by SIDC, the cloud hit STEREO-A in the late evening of March 9th, and delivered a few hours later what -at first sight- seems to be a glancing blow to Earth. The ongoing magnetic storm can be monitored via ACE-instruments and via the SWPC-site.

Screen-shots of three different eruptive events over NOAA 1164, showing today's evolution of the canopy from a pretty solid "ceiling" via a more ragged and bulged structure to an unstable and erupting prominence.
Courtesy of SDO (NASA) and the AIA consortium

Cut-out of SDO/AIA 304Å-image (19:59UT), showing the towering eruptive prominence above NOAA 1164. Estimated height at the time is over 400.000 km, that is 10 times earth's circumference.
Courtesy of SDO (NASA) and the AIA consortium

07 March 11 - Solar flares hidden in the X-ray background - During this morning's observation session (09:15 - 10:55UT) with a modest PST, no less than 6 flares were observed in H-alpha. However, comparing with today's SWPC event listing, only 2 events seemed to have occured during that timeframe. What's going on?

Picture underneath shows the X-ray evolution as measured by GOES-15. The M1,8-flare at 09:20UT and C4,9-flare at 10:21 can clearly be distinguished. SWPC correctly attributed these flares to NOAA 1164. In my opinion, Solarsoft mistakingly attributed the M1,8-flare to NOAA 1165, hence the corresponding movies show the wrong region. The observed eruptions are indicated on the Kanzelhöhe cut-out in yellow and green, and were labeled resp. 1 and 4.

The events 3 and 6 (blue numbering) occured in NOAA 1165, at the same location as the M1,5-flare earlier that morning (see complete Kanzelhöhe image taken during the flare). Events 2 and 5 are indicated by resp. pink and red and were located north of the filament. These 4 events either had the bad luck to occur in the descending phase of a much more powerful flare (event 2: slight "shoulder" in X-ray flux), or too short lived (events 5 and 6; see SWPC's User Guide page 5), or both (event 3).

An overview of the observed eruptions (timings are those of maximum brightness):

• 09:23UT - M1,8 - 1F - NOAA 1164 - 2 patches in middle portion of group. Fastly fading.
• 09:38UT - **** - SF - NOAA 1164 - Point at northern end of filament.
• 09:45UT - **** - 1F - NOAA 1165 - 2 relatively bright pathes.
• 10:18UT - C4,9 - SF - NOAA 1164 - Point and stripe at NE-side of NOAA 1664. Point evolved into stripe parallel to first one.
• 10:39UT - **** - SF - NOAA 1164 - Dot slightly to the north of the 09:38UT flare.
• 10:46UT - **** - SF - NOAA 1165 - 2 dots in same area as the 09:45UT flare, but smaller.

Finally, there are a couple of very nice movies of today's M1,2-flare in NOAA 1164 at LMSAL's Solarsoft. AIA171 and especially AIA304 show some great dynamics in the canopy overarching the sunspot region. More energetic flares in the regions 1164, 1165 and 1166 can be expected.

05 March 11 - With the preliminary SIDC-sunspotnumbers and the improved Bendel-Staps v20-formula, one can calculate a value for the SC24-amplitude. The rise of the smoothed sunspotnumber between July and August 2010 being 1,07, a SC24-maximum of 78 +/- 20 is predicted. The R25-formula can not yet be used (early August this year), but current estimates result in a maximum in the low 70's, with a slightly smaller uncertainty.

Figure underneath shows the monthly sunspotnumbers (SIDC) and the predicted values based on R_max=75, and an uncertainty of 20. The curves were calculated using Hathaway's method, time-adjusted to better fit the Waldmeier law (page 2), and finally Meeus smoothed. The obtained values seem to exclude Dalton-like or average amplitudes. Rather, they seem to hint to a maximum similar to those in the late 19th - early 20th century. The maximum is expected in August 2014, with an uncertainty of 16 months.

A word of caution: This is a statistical approach, meaning that uncertainties both in amplitude and in timing can deviate significantly from the predicted values, even at this stage of the cycle!

02 March 11 - There was an interesting teleconference today on the most recent solar cycle minimum and the missing sunspots. Supporting material is at NASA's Sunearth website, a more general article is at NASA's Science News. Nandy et al. have developed a model, building on 4 other models (see slide cut-out underneath), that can recreate the past solar cycle minimum which was unusually deep and long. They found that the poleward meridional circulation was fast in the first half of SC23, and slow in the second half. The fast movement causes a weak polar field and prevents magnetic field strengthening in the solar interior, whereas the subsequent slow movement delays the onset of the new cycle (and thus a lot of spotless days). Thus, by studying the internal motion of the meridional circulation, one could predict deep and long minima, and thus the related terrestrial spaceweather impacts. Particulary impressive was that their model showed very well the detail observed in the evolution in the surface magnetic field during the solar cycle (see bottom right of slide cut-out). Only the graininess of the local sunspot magnetic fields is missing.

In the Q&A session afterwards, a journalist asked if their observations are not contradictory to the work of other solar scientists. Nandy responded that their work is supported by observational evidence such as Howe and Hill (2009). Differences with work by other researchers such as Hathaway (2010) may be explained by the fact that the new model also takes into account the movement of magnetic field elements due to magnetic scattering, not only the meridional circulation. They showed, in my opinion, a healthy scientific spirit by not claiming that theirs was the overall truth, but by looking forward to further discussions with fellow scientists to refine the models.

There was no mentioning of the Livingston-Penn effect or Schatten's percolation theory (Hinode movie), and no prediction was made for the maximum of ongoing SC24. Also no reason/cause was given for the variability of the meridional circulation. Discussion is ongoing on the WUWT-site (here and here). David Hathaway also responded directly tot the author's article at the Nature website. Clearly, the last word on the missing sunspots hasn't been said yet!

24 February 11 - Peaking at 0735 UT this morning, a region still behind the NE solar limb produced a M3,5 flare. There's a nice SDO/AIA picture of the subsequent CME at Spaceweather, but also a truly impressive movie made by the Proba2-satellite. Notice the magnetic restructuring in the coronal loops after the flare and CME took place. The CME is directed away from Earth and should have no impact. Of course, the active region merits full attention once it gets around the limb.

Update: More great (and detailed) movies of this event are at Spaceweather, YouTube, and LMSAL's Solarsoft. This are all movies made by SDO's instruments. In particular the running difference movies are quite stunning (like this AIA 211 movie). The event was also SOHO's Pick of the Week. The M3,5-flare really seems to be caused by relatively tiny region NOAA 1163.

The CME from last week's X2-flare did not produce a big geomagnetic storm, because its strong magnetic field was oriented north (positive, opposite to earth's magnetic field). It did cause a moderate Forbush-decrease though, as can be seen in this picture made by the Oulu neutron monitor.

15 February 11 - First X-class flare of SC24 - At 01:56UT this morning, NOAA 1158 produced the first X-class flare of the ongoing solar cycle. According to the SIDC, this X2,2-flare was accompanied by a CME (movie at Spaceweather) which is expected to reach Earth by 17 Feb 11. There is also a mild proton enhancement ongoing, but it does not seem to reach the event treshold. SDO-movies of the event are at LMSAL's Solarsoft. There is also a very impressive movie of an EUVI-wave expanding from the blast site (see screenshot underneath). NOAA 1158 may further produce high energetic flares.

Table underneath shows the 10 longest periods (since 1976) without an X-flare. With today's X2,2-flare, a new record was set. Indeed, there were 1524 days since the previous flare on 14 Dec 06, making it almost a half year longer than the previous record period. The current solar cycle transit also holds the records for longest period without C- or M-class flare (see table). The last more powerful flare than today's dates back from 13 Dec 06, also produced by NOAA 0930 (X3,4).

Update (22 April 11) - Rotating sunspots spin up a super solar flare.

Screenshot from the SDO 304Å-movie only 3 minutes prior to maximum showing the parallel ribbon flare along the magnetic inversion line
Courtesy of SDO (NASA) and the AIA consortium

Screenshot from the SDO EUVI-wave difference movie
Movies courtesy Nariaki Nitta, Lockheed-Martin

14 February 11 - NOAA 1158 is displaying some very nice activity. The mixed polarity resulted in a M6,6 flare yesterday and a M2,2 just minutes ago. There are some great SDO-movies at LMSAL's Solarsoft page. Notice how the flare follows the magnetic inversion line. SIDC forecasts geomagnetic influence from the M6,6 flare's CME for 16 Feb 10.

So far, SC24 has produced only 4 High Energetic Flares (M5 or higher), the highest a M8,3-flare produced by NOAA 1046 on 12 Feb 10. With its current magnetic complexity and McIntosh-classification (Eac), there's a 14% chance on additional M-flares and (only) 2% chance on X-flares (if it doesn't become bigger or even more complex of course...).

Courtesy of SDO (NASA) and the AIA consortium

02 February 11 - Over the last couple of weeks, I've been working to update the general solar cycle page. Amongst other, it features:

• An overview of the main characteristics of each solar cycle
• Top 50 of the biggest sunspotgroups since 1874
• Top 50 of flare producing sunspotgroups (since 1976)
• Yearly synoptic maps for SC23 and SC24

I also added a few words on the Gnevyshev-Ohl rule, which was apparently broken by SC23. The last time this happened was during the Dalton minimum about 200 years ago.

13 January 11 - Today, the VRT reported on the flooding that is taking place over various areas in the world (Philippines, Brazil, Sri Lanka, Australia, and the heavy December snowfall in USA and Europe). Amazingly, they did not blame this on CO2 or global warming, but on a natural phenomenon called... La Niña. The movies are very instructive. Just a reminder: El Niño en La Niña exist already for hundreds of years and longer, so well before IPCC summoned CO2 to explain 20th century global warming. Personally, I'm very pleased with our national broadcast corporation starting to differentiate between the causes that affect (extreme) weather. Underneath the most recent Jason-image of the Pacific-region showing the still obvious La Niña.

10 January 11 - New insights into sun's photosphere reported - BBSO's 1,6 m solar telescope reveals "... that the Sun can generate magnetic fields not only as previously known in the convective zone but also on the near-surface layer". "We believe small-scale turbulent flows of less than 500 km to be the catalyst," said NJIT Research Professor Valentyna Abramenko at BBSO.

10 January 11 - Can most of the rise in the satellite-era surface temperatures be explained without anthropogenic greenhouse gases? - Interesting study by Bob Tisdale on the WUWT-website indicates that natural variables could be responsible for approximately 85% of the rise in global surface temperature since 1982. This basic evaluation indicates the secondary effects of ENSO require further research. See also my own rudimentary research on this matter at Reconstructing the Climate Change (February 2007).

07 January 11 - Plasma jets are prime suspect in solar mystery - New high-resolution images made by SDO and Hinode point to type II spicules as the most likely source of the hot solar corona. These 100 km/s rising jets deposit hot plasma into the corona before rapidly disappearing. The biggest challenge now is to understand what drives and heats the material in these spicules. So, the mystery is not solved yet, but the solar detectives gained one important clue! The lead author of the Science paper is the Belgian Dr. Bart De Pontieu at the Lockheed Martin Solar and Astrophysics Laboratory. Quick-time movies are available at Science/AAAS, containing additional information.

Screen shot from the S8-movie at Science/AAAS

19 December 10 - Another one for VRT's blunder book. Today's political program "The Seventh Day" took 2010 in review. At one point, a clip was being shown with the worst catastophes the world had experienced this year (based on AP's article?). It boiled down to only 4 (!): Floods in Pakistan, floods in Europe (and Belgium), the Haïti earthquake and the oil disaster in the Gulf of Mexico. Not such a bad choice, but they were intermixed with UN secretary-general Ban Ki-moon's speech at the Cancun climate conference. This implies that climate change causes earthquakes and blows up oil platforms. Yikes!... It also shows there were very little catastrophes in 2010: Otherwise they would surely have been shown in the clip.

In the discussion afterwards, that bald guy (no idea who that is) adds the forest fires as a 2010 catastrophe and starts explaining how this creates a positive feedback (CO2 causes drought => drought causes forest fires => forest fires creates more CO2). He should better have read NOAA's analysis on this. Oneliners such as "you do not negotiate with nature" were properly abused to suit his own benefit. Actually, in those 7:37 he uttered more rubbish than I care to comment about. It all boils down to CO2 as being the main climate change driver, and that it is a settled fact.

I, and many, many others do not agree with these two statements. Watts up with that or CO2-Science are just a few of excellent websites to find out how things really work. Watching the nonsense of today's discussion, it's really no wonder people's support for man-caused global warming is declining!

14 December 10 - 4 years without an X-flare! Today it is exactly 4 years since the Sun unleashed its last X-flare. Indeed, it was on 14 December 2006 that NOAA 0930 produced the last of its series of 4 powerful X-flares. The period of 1461 days beats the previous record of 1344 days that occured during the descending phase of SC22 (1992-1996). This table provides a comparison with other periods. Graph underneath depicts months with powerful flare activity.

13 December 10 - No more solar wind for Voyager I spacecraft. But it is still not in interstellar space... yet!

02 December 10 - SOHO celebrates 15 years. Congratulations to the entire team that made (and still is making) this the greatest and most successful solar mission ever! SDO and others can stand on the shoulders of a true giant!

12 November 10 - Sun's magnetic building blocks revealed by Sunrise (Physorg). Some impressive movies of the Sunrise-launch and ending can be found at their website. Sunrise is a 1m-telescope with a 0,05" (100 km) resolution in visual, UV and magnetic at a working (balloon) altitude of 36 km taking high-cadence pictures for a couple of days uninterruptedly (8-14 June 2009).

06 November 10 - NOAA 1112 is back as region 1121 and has produced already a few M-flares (e.g. M5,4 at 15:36UT; Solarsoft's SDO-movies). The region is not impressive from the sunspot point of view (in fact, the smallness of the sunspots is quite misleading), but the magnetograms clearly show intermixing in the trailing part of the region. Looking closely at the magnetogram, it almost looks as if the trailing part of one region is interacting with the preceding part of another region. Again, these reflections can only be based on the magnetograms, as neither in visual nor in the other wavelengths, there are indications for this. As long as this mixed polarity area exists, further M-flaring can be expected.

Courtesy of SDO (NASA) and the AIA consortium, SOHO/MDI and Catania

16 October 10 - This animation shows NOAA 1112 and surroundings (southern solar hemisphere) in visual (SDO/HMI Intensity), H-alpha (Kanzelhöhe) and 193Å (SDO/AIA 193). The bright areas in H-alpha and 193Å correspond to NOAA 1112 sunspot region, while the filament is situated more southerly. Such long filaments may become unstable and result in a CME. Stunningly detailed movies of this area can be found at LMSAL/Solarsoft. The sunspot regions NOAA 1113 and 1115 are well visible in visual and H-alpha, but not in 193Å. Notice also the different outlook between the coronal hole and the filaments, and some of the H-alpha prominences are visible in 193Å. The images were made on 15 October between 12:15 and 12:45UT.

Update 17 October 10 - The mixed magnetic polarities in the small sunspots of NOAA 1112 have resulted in an impulsive M2,9 flare yesterday peaking at 19:12UT. The filament just south of this region was unaffected by this explosion, and seems to have grown in length.

26 September 10 - Sunspotgroup or pore? - During the last 72 hours, some activity is going in a region about 15° west of NOAA 1109. There has been some discussion on whether or not this has to be classified as a sunspot group.

Certainly yesterday, it concerned only pores, as underneath cut-out of the highest-resolution intensity-image by SDO (08:11UT) clearly shows. Some observers didn't even see the pores with appreciable telescopes.

The difference between a pore and a spot has been explained in slides 32-34 in this SIDC-presentation.

The area does merit interest, because both on September, 24th as on today's SDO-images, a small speck can be seen. However, the big observatoria did not report a sunspot on the 24th, and it is unlikely that they will today, unless some new additional magnetic flux boosts those pores to real spots. The 06:00UT SDO-image shows again only a pore in this area. For the latest developments and images, see the SDO website.

Courtesy of SDO (NASA) and the HMI consortium

19 September 10 - NOAA 1106 and the McIntosh-classification - Recently, solar observers have had a hard time in classifying NOAA 1106: Does this region concern 1 or 2 sunspot groups? If one considers this as 1 sunspotgroup, a very unusual sunspot classification emerges: Fsi (or Fso). Many observers choose the latter (and right) classification, because there were some very small sunspots between the two main spots that seems to be linking them, but it still remains a weird view. So, how unusual is this type of classification (Fso, Fsi, Fao, Fai)?

From my earlier study on the McIntosh-classification (The Big CV-project), an F-group on its own is already something quite rare: Of the 36530 McIntosh-classifications made between 1944 and 2009, only 737 (2%) were considered an F-group. Most of these were complex ("c") or had a big main spot ("h" or "k"). In total, only 84 classifications (0,2%!) were considered to be of the Fso-Fsi-Fao-Fai-type. Rare indeed! Underneath a few SOHO-images of SC23-groups with this type of classification (Fso, Fsi, Fao, Fai). Note that in both case, magnetic observations confirmed this was one sunspotgroup.

15 September 10 - Livingston-Penn and the possibility of a new Little Ice Age - I was interviewed today by our national broadcast radio on the Livingston-Penn effect, and the possibility of a New Maunder-minimum and Little Ice Age. I avoided sensationalism, and used a lot of "if"'s. The audio is still available at the Radio-1 website (in Dutch).

17 August 10 - Why rare events are a certainty - This post by Roger Pielke Jr. makes some relevant reflections in view of all the extreme weather that is experienced by Russia (notice the cold patches...), China and Pakistan/India (monsoon has perfectly natural causes like El Niño or PDO), Central Europe (some very thoughtful comments by President Havel on the Czech floodings in 1997 and 2002), and South-America (it's winter there!...). These are extensively covered by -at least- the Belgian media, probably because of the lack on hurricanes (globally) so far...

Weather is not climate!

16 August 10 - Synoptic maps are updated - The page with synoptic maps (yearly) and contourmaps (over SC) has been updated.

Synoptic maps give an idea on how the activity is spread over the solar surface. This can be done by dividing the solar surface in areas of 10° longitude by 10° latitude. Then, over the course of a year, the total number of groups that appeared in each of these sectors is determined. As from 1996 onwards, they provide a yearly overview of the activity-spread concerning the number of groups, the activity areas (according to Waldmeier-classification), the sunspotarea, the number of M- and X-flares, and the flare-fluence.

14 August 10 - First proton event of SC24 - Earlier today, NOAA 1093 released a modest C4-flare (Max at 10:05UT) which was accompanied by a CME and a proton event. This proton event is small, but it is the first of the new solar cycle (see NOAA/SWPC list).

The flare took place alongside the filament which can be seen on today's (07:03UT) Kanzelhöhe H-alpha image (at left). This filament stretches itself between NOAA 1093 and the quickly developing NOAA 1099. SDO's AIA304 image of 09:45UT (at right) shows the CME already departing (lower righthand corner; not the prominence at right!). SIDC (RWC Belgium) expects a small geomagnetic effect around 17 August. More SDO-movies of this event can be found at LMSAL's Solarsoft.

The proton event is still ongoing. Peak proton flux (+/- 12 pfu) seems to have been reached about 3,5 hours after the flare reached its maximum X-ray brightness (see diagrams; proton flux at right). This is consistent with a not very energetic event.

02 August 10 - NOAA 1092 and disappearing filaments - Yesterday morning, the northern part of a filament twin erupted. The spectacular and complex event was recorded by SDO and Stereo. Stunning movies can be found at the websites of Spaceweather and LMSAL's Solarsoft (SDO, Stereo). Based on SOHO EIT 304-images and a Holloman report (SWPC), the southern part disappeared between 16:55 and 21:00UT. No movies are available (yet) of this event.

Some sites (Spaceweather, IPS) state a coincident C3-flare in NOAA 1092 was at the origin of the filament eruption, while others (SIDC, SWPC) merely noted the coincidence. From the SDO movies, in particular the AIA 304, it does seem that the filament is already erupting at around 07:15UT, more than 30' before the onset of the C3-flare (simply use the pause and play buttons). A shock wave does seem to ripple through the solar atmosphere after the C3-flare, but it arrives at the (northern) filament site well after the eruption's onset.

Interestingly enough, the C3-flare was preceded by a small B3-flare with maximum at around 06:55UT. It is unclear whether this flare originated in NOAA 1092, and if it was the cause of the filament eruption.

Due to the complexity and timing of the various filament eruptions and flaring events, the SIDC expects geomagnetic disturbances possible between late 02 Aug and 04 Aug. (Source: SIDC)

Meanwhile, NOAA 1092 is now a naked eye object, but it needs well trained eyes to see the barely visible speck. Also, in contrast to some classifications (SWPC, STAR), this really seems to be a "h" type group rather than a "k" type (according to the McIntosh-classification). The small irregularities in the umbra and penumbra of the main spot do not justify it to be classified as an asymmetric spot.

First analysis of this global solar event at Science at Nasa and additional movie at Universe Today (15 December 2010).

12 June 10 - Active region NOAA 1081 - Earlier today, from a loose heap of small sunspots a.k.a. NOAA 1081 originated quite unexpectedly an M2-flare (00:57UT) and a C6,1-flare (09:17UT). Impressive movies of these events can be found at the SDO-website and especially at LMSAL's Solarsoft (M2, C6). According to the NOAA/SWPC, the M2-flare caused some proton-enhancement without reaching the treshold-level. The C6-flare was followed some 10 minutes later by an impressive mass ejection. Picture underneath is a screenshot from SDO's AIA 304 movie.

05 May 10 - Proba-2 data now in near realtime online! - As announced by the SIDC yesterday, PROBA-2 data and images are now online. These images are indeed near realtime, but unfortunately, they are in fits-format. No problem though: the images can be viewed and toyed around with by simply downloading and installing SAOImageDS9, available for almost every operating system.

The results are quite impressive, as demonstrated by the image underneath, showing today's C8,8-flare in NOAA1069 at its maximum at 11:52UT. This region, at its high latitude of 42° has grown considerably over the last 24 hours and still has a mixed polarity. Hardly an hour ago, it not-surprizingly produced an M1,2-flare. And it seems more can be expected...

Update: Based on the Proba2-images, I've added a small movie of today's M1-flare. Images span from 17:07UT till 17:37UT, in lapses of about 2 to 5 minutes. Graininess and "moving around" of the image is courtesy of my clumsy moviemaking. Nonetheless, it can be seen that the magnetic field (arch) over NOAA1069 disappears during the flare (images 6 and 7), then gradually restructures and re-establishes itself in the course of about 15 minutes. The flare starts at 17:13UT (3rd image), reaches maximum at 17:19UT (5th image), and ends at 17:22UT (6th image).

05 May 10 - New solar astronomy magazine online - The first issue of Solar Observer is now online. It's a magazine that wants to cover all areas of solar astronomy, and for this huge scope it can count on contributions of both amateur and professional solar astronomers. It therefore targets a broad range of readers, from the very beginner to the advanced astronomer. If this level of science (no maths!) and number of articles can be maintained, it may quickly become the Sky & Telescope of solar astronomy magazines! Congrats to the editorial board!

04 May 10 - 5 sunspotgroups today... - ...but they are all very small. According to one of today's SOHO-images, Sunspotnumber could be as high as 59 (5 groups, 9 spots). It remains to be seen if all these groups will be counted as sunspotgroups, due to the smallness of some. The final ISN for this day will probably be significantly lower (est. 25-40). A better index is the Classification Value (Malde, 1981), based on the McIntosh-Classification. With a value of 9 (2 Axx, 2 Bxo and 1 Bxi), this gives a much better idea of the true solar activity (= low!!).

The still to be numbered region on the high northern latitude is at an estimated +41°. This is the highest latitude for a SC24-region so far. It also produced a C3-flare this evening. Latitude nor flare-production are unusual for such a region. At the moment, it is the most prominent region on the solar surface, developping quickly and having some mixed polarity. Only NOAA1067 is also well visible, the other groups are fading or have faded away.

23 Apr 10 - SDO's first light images and movies - Truly impressive clips at SDO's website, with explanations at the renewed Science-at-Nasa-website, and discussions at WUWT.

13 Apr 10 - Prominence-whopper! - A large prominence erupted earlier today into a spectacular CME. Movies can be made at the SOHO Movie Theatre (simply click C2 or C3 and fill in today's date, i.e. 2010-04-13) or seen at Spaceweather.

Based on early H-alpha observations by André Gabriel, a renowned Belgian solar observer, and combining with C2- and C3-images from SOHO's coronographs (LASCO), the evolution in (radial) speed of the CME could be calculated. As can be seen, the speed of the CME is accelerating from about 20 km/s until it reaches a final speed of about 400-500 km/s, close to the solar wind speed. There's probably a spread of 50-100 km/s on the last couple of data points (2 of C2 and all of C3), due to resp. CME features becoming less bright and much smaller resolution in the C3-images. The data-points were based on a bright whisplike feature on the top of the inner CME-structure (notice the faint outlines of the outer CME in the above image). At around 08:45UT, the height of the CME in H-alpha was about 300000 km above the solar surface, but around 15:00UT, its distance had already increased to over 7 million km!

12 Apr 10 - On solar flares... - Some interesting articles on solar flares appeared recently on the PhysOrg.com-website:

• Magnetic ropes tie down solar eruptions
• Errors in hypothesis linking solar flares to global temperatures (discussion at WUWT)

05 Apr 10 - Predicting SC24-maximum from early SC24-sunspotnumbers - Article

14 Mar 10 - Solar Conveyor Belt - From Science at Nasa: Solar "Current of Fire" speeds up. The article also confirms 2006-reports of a very slow moving bottom of the conveyor belt (See Hathaway (2006)). Compare to:

• Rachel Howe and Frank Hill (2009): Mystery of the missing sunspots, solved? (concerns jetstream)
• Mausumi Dikpati (2006): Scientists Issue Unprecedented Forecast of Next Sunspot Cycle
• Kenneth Schatten (2007): Percolation and the solar dynamo (concerns an alternative view on sunspot formation + Hinode-movie)
• Livingston and Penn (2008): Are sunspots disappearing? (article)
• Rachel Howe (2009): Solar Interior Rotation and its Variation (Chapter 10: Tachocline variations)
• Howe, Christensen-Dalsgaard, Hill et al. (2000): The pulse of the solar dynamo (variations at the tachocline, which since then, seem to have disappeared).

Further comments and discussions at Anthony Watts' blog.

09 Feb 10 - Disappearing filament - To the east of the active region NOAA 1045, part of a filament disappeared between 07 and 08 February. As can be seen in Kanzelhöhe's H-alpha images underneath, the filament snaked itself between regions of opposite magnetic polarity, but the southern part had disappeared by 08 February. It is interesting to note that this region is still visible in the SOHO's EIT and GOES14 SXI images as a dark river meandering between the regions of opposite polarity. Moreover, a spectacular loop developed itself above the northern part as can be seen in the EIT and SXI images. No conclusive material yet on the timing of the disapperance and whether the filament dissolved or erupted. (Full image)

07 Feb 10 - Fire in the hall!! NOAA 1045 has produced 3 M-flares overnight, one of which was a high-energetic M6. It was the first high-energetic flare (M5 or higher) since June 2007 (NOAA0960). More medium flares can be expected as long as there exists a mixed polarity in the sunspot group (see magnetogram underneath). The group seems to have grown into a McIntosh-class Eac. The chance on an X-class flare seems to be very small though (2%). Movies of the flares can be found at Solarsoft.

29 Jan 10 - First results of the PROBA-2 satellite. All data will be freely available tot the public at their Science Center, which also hosts a very nice Outreach-site (Suntrek).

Meanwhile, the Solar Dynamics Observatory is getting ready for its "no-earlier-than-09-February" launch. See Universe Today for a movie of its mission.

25 Jan 10 - Interesting presentations on "Aspects and consequences of an unusually deep and long solar minimum" during the AGU Fall meeting (Dec 2009). (Source: Bad Astronomy and Universe Today Forum)

20 Jan 10 - I've "rewired" the entire website. That way, I hope it's easier to use. More to come.

19 Jan 10 - M2,3-flare in old region NOAA 1039 - It was the first M-flare since 25 March 2008, that's 665 days ago - an absolute record since measurements began in 1976 (see Archives). Movies at Solarsoft. The S25E88-position seems somewhat off the mark, as the region still has to round the solar limb.

Update: NOAA 1040 produced in a very short timeframe 6 M-flares (source: SEC), after which it remained quiet.

15 Jan 10 - Giant ribbon at the edge of the solar system