Castle Point Astronomy Club
1969-2019 - 50th Anniversary Year
The Sun in Hydrogen alpha by Ron Mansfield
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The Sun in Hydrogen alpha by Ron Mansfield
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Taken at the 2010 Kelling Heath Autumn Equinox Star party. Afocal photograph using the Solarscope Solarview dedicated hydrogen alpha telescope owned by C.P.A.C.

This photograph demonstrates that it is possible to get interesting pictures using relatively unsophisticated techniques, even though the telescope itself cannot be considered unsophisticated. Essentially, it was a case of doing nothing more than holding a point and shoot digital camera up to the eyepiece and snapping the shot. The telescope has to be tuned to fractionally different wavelengths for features such as the prominences of which there are several examples in this image, or alternatively for signs of activity on the Solar disc, which can also been seen here. In order to get both areas of activity in the one image, two separate photographs were taken using slightly different tuner settings. The two images were then combined to create the single image seen above.

There aren't that many things in the realm of amateur astronomy that can be easily observed to undergo perceptible change over fairly short timescales. Prominences, filaments and sunspots are amongst the exceptions. They are all likely to exhibit noticeable change over a matter of a few hours or a few days.

Features such as prominences and filaments, and also of course the far more easily observed sunspots, are all intimately linked to the Sun's very dynamic and constantly evolving magnetic field. Basically, all three of these types of feature involve ionised gas becoming temporarily trapped by the local magnetic field. Not only does it give rise to interesting observable activity on the surface of the Sun, but the Solar magnetic field also has the potential to give rise to spectacular observable phenomena here on Earth in the form of the aurorae the Northern and Southern Lights.

The Sun's magnetic field is a complex and far from thoroughly understood beast that makes itself felt across the length and breadth of the Solar System. Its influence extends way beyond the Earth, to far out beyond all the planets. The constant stream of charged particles from the Sun, travelling at speeds as high as 900 kms/sec, carries the Sun's magnetic field out to a distance of perhaps 200 A.U.

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