Friday, 15 July 2011

More pretty stuff

Like a glowing flower in space, the Trifid nebula is suspended in the celestial firmament above the Lagoon nebula in the constellation of Sagittarius the archer. Visually, the colours cannot be seen, and in fact look oddly reversed from that on photographs. This is a wonderful photographic target, that rises high in the sky from mid to tropical latitudes, southwards. The combination of colours arises from general 'dust' that scatters the light, reflecting and enhancing the blue colour of hot stars that light it up, and hydrogen that fluoresces at red and blue wavelengths. Much of the hydrogen light is resonant fluoresent, i.e. glowing back at the extreme ultra-violet wavelengths of 121.6nm and beyond (compared with our visible range 430-630nm). However, this harsh, invisible-coloured light is only detectable above the atmosphere. In this light, our galactic neighbourhood would look vibrant. We just get to see the little red portion (656.3nm) on our photos and, visibly only the tiny fraction that is blue(486.1nm) is detectable to our eyes at night. The picture was taken on a Vixen 4" refractor (with some serious chromatic aberration that I've already reduced) and was just 1 5-minute exposure. Compressed quite badly, or as I would say, Jpegged to high heaven!

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