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PostPosted: Tue Sep 09, 2014 6:05 pm 
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The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 379b 2014 July 20

Here is the latest round-up of news from the Society for Popular Astronomy. The SPA is Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/

SPA SOLAR SECTION REPORT FOR MAY 2014

By Geoff Elston, SPA Solar Section Director

The most unusual news item that caught my eye recently was that new research had suggested that rates of lightning here on Earth might be associated with space weather (the general term used to describe the Sun’s influence on the Solar System, and in particular the Earth). The research indicates that the amount of lightning we get might be modulated by the solar wind as it interacts with the Earth’s magnetic field. No one knows for certain if this association is real (and this latest research contradicts some earlier studies), nor how lightning and space weather could be physically connected. Further research is needed to prove the case either way.

Rotation Nos. 2149 – 2150

The Mean Daily Frequency stayed level at 5.76 in May with a very slight dip in the Relative Sunspot Number to 76.34. Sunspot activity remains at a high level. In the current Sunspot Cycle only October 2011, November 2011 and January 2014 were higher (6.03, 6.75 and 5.97).

WHITE LIGHT ACTIVITY

May saw a lot of sunspot activity up until the last week of the month. We have not seen any sunspots big enough to be seen with the protected unaided eye but there have been plenty of sunspots to see (and image) on most days and a couple of surprises along the way. Two groups: AR2047, and preceding it: AR2051, were nearing the W limb by the 3rd. AR2051 had appeared and developed rapidly within the previous two days (it was not visible on the 1st). Both showed extensive structure and because of the rapid development, AR2051 it was thought could produce some powerful flares. At the CM was AR2049, comprising 3 main spots, and the leader having an oval shape. AR2050 (north of AR2049) and AR2052 (moving away from the E limb) completed the picture. By the 5th AR2051 was nearing the W limb and just as it was about to pass over the limb, it unleashed an M-class flare and a Coronal Mass Ejection (CME) on the 6th. The centre of the solar disk was by then briefly quiet with mostly small spots. Our attention was swiftly drawn towards the E limb with the arrival of AR2055 and AR2056 both showing bright faculae around them. AR2056 released an M-class flare (but no CME) on the 8th. Both AR2057 and AR2059 developed rapidly as they were following very closely behind AR2056. These together with AR2058, slightly further to the south east, were making the whole SE region look highly very active with sunspots. As all this activity moved closer to the CM the interplanetary field became unsettled and there were some minor aurorae at high latitudes. It looks as if AR2058 produced a filamentary eruption and two CMEs on the 11th.

All observers reported a sustained period of sunspot activity with increased numbers of sunspot groups and individual sunspot counts as we past through the middle of the month. More sunspot activity appeared over the E limb in the form of AR2060 and AR2061 following behind AR2058. They all showed mostly small spots and numerous pores. The sudden “overnight” appearance and rapid development of AR2063 on the 14th also added to the mix. By the 17th things were becoming quieter. Both AR2056 and AR2060 were still capable of producing flares because of their complex magnetic fields but they did not do so. As we went into the last week of May the Sun became much quieter than it had been earlier. Near the W limb were AR2061 and AR2066 mostly small spots with bright faculae all around them and stretched along the disk were AR2072, AR2071 and AR2073 all comprising of small spots. I received many really great images via email some of which are shown here. Thanks to everyone for taking the time and effort to produce and send these images to me.

MDF: 5.76 R: 76.34

H-ALPHA ACTIVITY

The high level of sunspot activity also led to a high level of plage and filament activity in Hydrogen-alpha. Plages were observed around nearly all of the sunspots visible throughout the month. Two dark filaments were noticed near to AR2049 and AR2050 on the 2nd. Numerous prominences were seen on 6th along the NE, E and SW limbs. AR2055 and AR2057, both near the NE limb, showed extensive plage and filament activity on the 7th as well as a number of detached prominences at the NE limb. By the 10th much of the plage and filament activity was clustered around the NE limb region associated with sunspots AR2055 to AR2059 grouped on that part of the solar disk at that time. Over the following two days a number of plages were observed on the NE quadrant connected with the sunspots there and two broad convoluted filaments were seen on the SE of the disk. On the 13th and 14th plage and filament activity was seen right across the solar disk while prominences were largely confined to the E and SE limbs. There was again lots of plage and filament activity on the 16th, particularly a dark elaborate filament just north of AR2063, but not many prominences. The filament persisted over the next couple of days becoming darker and broader by the 18th. On the same day a cluster of dusky filaments was seen near the W limb together with some prominences slight farther south along the limb. By the 19th we were seeing mostly small sunspots and in H-alpha we too were seeing a number of plages and filaments across the disk. The 21st saw many filaments particularly a long intricate filament to the south of AR2069. There were some complex prominences on the NE and W limbs with some detached from the solar limb. As we reached the last day of May many were delighted to see a fine and extensive display of tree-like prominences along much of the SE limb and Ian Lee captured these in his drawing of the 31st.

MDF (P): 8.02

My thanks to Alan Heath who has just sent to me a copy of his latest research on the appearance of unaided eye sunspots and the solar cycle. Alan successfully published an earlier paper on this subject in the June 1994 issue of the Journal of the British Astronomical Association. By using his own observations, made from 1959 and now updated to the present day, his research suggests that the appearance of unaided eye sunspots on the Sun reaches a peak after sunspot maximum has taken place. Separate research suggests that they occur before and after solar maximum. Alan is cautious and adds that his research is based on just his observations. I wonder if this is something we should consider doing within the Solar Section? It would be a long-term programme but might reveal similar evidence to support Alan’s research.

Bulletin compiled by Clive Down

(c) 2014 the Society for Popular Astronomy

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