Orwell Astronomical Society (Ipswich)

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24 April 1985: Start Of A Sunspot Cycle?

After a long period of solar inactivity - several months with few sunspots - I was surprised to see what proved to be a naked eye sunspot group on 24 April 1985. The seeing was not marvellous at 09:20 UT on that day but I made a drawing, an enlarged copy of which is shown below, by copying an image projected by my 5.5 cm refractor.

To check groups for naked eye visibility, I use over-exposed black and white film negatives. I keep a small selection of these to hand, of different densities, though usually one "standard" pair is suitable for a clear sky. The pair is held so that one looks at the sun through the two layers of film. NOTE: do not use this technique for observing the sun through a telescope - always use the projection method.

The group was still prominent on 30 April when near to disappearance round the solar limb. It was visible but much depleted on 17 May after a trip round the back of the sun. Meanwhile, on 13 May another large spot, also visible to the naked eye, was observed near the centre of the disk. These spots so close to the sun's equator indicate a new cycle has started or at least is not far off.


Roy Adams