Popular Astronomy

Share to Facebook Share to Twitter Stumble It More...

Solar Highlights for January 15

Solar Rotation Nos: 2158 to 2159

Low Sun and poor weather have taxed our section members this month meaning that there were some days when we were unable to observe.

The current Sunspot Cycle continues to produce surprises as it shows not much evidence of slowing down. The sunspot graph for the SPA Solar Section shows the level of sunspot activity to be continuing at much the same level as before. Instead of a rapid rise to sunspot maximum and then a gradual decline thereafter we seem to have a lower but longer sustained period of sunspot activity.

Thank you to Alan Heath for his "Longitude of Solar Active Regions 2014" report.

Here are the highlights for January 2015.

We saw a very active Sun as the New Year began.

Active Region (AR) 2253 was between the Eastern (E) limb and the Central Meridian (CM) and had been developing rapidly. It also had an unstable magnetic structure meaning it was very likely to produce solar flares. Visible to the protected naked eye on the 3rd and the 4th it was wider than the planet Jupiter. It crossed over the CM on the 5th still without any flare activity but it was still bigger than the other sunspots visible at that time: AR22548 and 2256 nearing the W limb; AR2251 and 2252 now west of the CM and AR2255 which was at that time between the E limb and the CM.

There was a geomagnetic storm on the 7th visible from the higher latitudes of the Earth but this was not due to AR2253 but the result of a sudden and short change in the interplanetary magnetic field allowing energetic solar particles into the Earth’s magnetic field where they produced aurora.

AR2253 decayed away as it neared the W limb around the 9th and 10th but by then AR2257, which had appeared suddenly on the solar disk by the 7th, and had grown rapidly as it heading westwards. AR2261 had also come over the E limb around the 8th and looked to be developing as it drew ever closer to the CM. AR2257 eventually produced a M-class flare in the early hours of the 13th (0424UT) that created a brief radio blackout over the daylight side of the World (the Indian Ocean and Australia mainly).

By mid-month, only AR2261 was visible at the CM as AR2257 and the nearby sunspots were by then close to the W limb. The Sun then became quiet. On the 20th AR2266, a grouping of 7 sunspots (with 2 main spots), was just over the CM but apart from that there was not much else to see.

It was not until the 22nd that we began to see something coming over the E limb. This turned out to be AR2268 a pair of fairly substantial sunspots and this developed over the next few days. There was a sudden upturn in sunspots on the 27th alongside AR2268. As we came to the end of January AR2268, 2271, 2275 and recent arrival AR2277, just over the E limb, all posed a possible solar flare threat.     

Well done to Alan Heath who observed on 25 days. Brian Gordon-States managed 24 days and Jonathan Shanklin on 22 days.

SPA Sunspot Mean Daily Frequency (MDF) for January: 4.96 
SPA Relative Sunspot Number for January: 74.79


There were some fine prominences on the E limb on the 2nd including a long hedgerow type.

A high tree-like prominence was imaged on the W limb by Richard Bailey on the 11th.

A hedgerow with a high jet-like prominence was imaged on the W limb on the 30th at 1250UT by Julia Wilkinson and drawn by Ian Lee. In addition, a low hedgerow prominence was visible on the E limb. The tallest part of the W limb prominence was still visible on the 31st (but the lower sections had by then gone over the W limb) while the low prominence on the E limb had become easier to see due to the Sun’s rotation bringing more into view. 

There were a number of bright plages seen throughout the month mostly associated with the sunspots. AR2266 particularly showed numerous plages around it from the 19th to the 24th as it crossed the solar disk.

Several fine dark filaments were visible on the 8th, 14th, 20th, 22nd,and the 24th. Ian Lee drew my attention to a long broken filament on the disk nearing the W limb on the 20th where there were a number of complex prominences along the W limb.

No solar flares were reported.


Detailed count records of Active Regions and Relative Sunspot Numbers came from: Richard Bailey, Michael Fullerton, Brian Gordon-States, Alan Heath, Mick Jenkins, Ian Lee, Jonathan Shanklin and Julia Wilkinson.

Images and drawings were supplied by: Richard Bailey, Mark Beveridge, Carl Bowron, Mick Jenkins, Ian Lee, Cliff Meredith, Julia Wilkinson, Pete Williamson and Brian Woosnam.

Geoff Elston
SPA Solar Section Director

Added by: