|
jgs001
|
 |
« on: October 14, 2008, 08:33:03 am » |
|
It was misty and cloudy last night, the moonkept poling her face out in some of the thin parts of the cloud, enough so that I could get this ...  |
John Canon 450d, EF-S 18-55 IS, 55-250 IS, Raynox DCR250 HQE5 + C80ED & Vista 80s. NexStar Skymax 102 SLT. *** My Astro Blog *** |
|
|
|
|
|
brianb
|
|
« Reply #1 on: October 14, 2008, 10:18:05 am » |
|
Nice image (but nasty cloud, and too bright moon)
BTW the bright aureole with a coloured edge is called a corona, not a halo - a halo would be 22 degrees from the Moon and have a dark space inside it. A halo is caused by refraction within ice crystals, a corona is caused by diffraction as the light is bent past very particles in the air - usually water droplets, but could be anything, even dark smoke, as the light doesn't actually go through them.
|
|
|
|
|
|
jgs001
|
|
« Reply #2 on: October 14, 2008, 10:50:39 am » |
|
Thanks Brian, and thanks for the correction and information. Is a Halo always at 22 degrees ?
|
John Canon 450d, EF-S 18-55 IS, 55-250 IS, Raynox DCR250 HQE5 + C80ED & Vista 80s. NexStar Skymax 102 SLT. *** My Astro Blog *** |
|
|
|
brianb
|
|
« Reply #3 on: October 14, 2008, 11:52:09 am » |
|
Is a Halo always at 22 degrees No, there is a (rare) 47 degree halo ... but the angles are fixed by the refractive index of the ice crystals, which varies with the wavelength of the light (the crystals are acting as tiny prisms) which is why the halo shows colours. The corona shows colours too because different wavelengths diffract differently. But the size of the corona depends on the size of the cloud particles, the smaller they are the bigger the corona. When there is a well-formed corona, it's because the particles are all a similar size. |
|
|
|
|
|
jgs001
|
|
« Reply #4 on: October 14, 2008, 12:00:14 pm » |
|
Thanks very much Brian
|
John Canon 450d, EF-S 18-55 IS, 55-250 IS, Raynox DCR250 HQE5 + C80ED & Vista 80s. NexStar Skymax 102 SLT. *** My Astro Blog *** |
|
|
|
brianb
|
|
« Reply #5 on: October 14, 2008, 12:23:52 pm » |
|
As it happens I shot the corona last night, too - something to do whilst waiting for the cloud to clear, managed only 3 VS obs last night. Here's my image - Canon 40D, 400mm, 1/15 sec f/5.6, ISO 100  |
|
|
|
|
|
jgs001
|
|
« Reply #6 on: October 14, 2008, 01:02:41 pm » |
|
Nice one Brian, I merged exposures to get any lunar detail, but you got some coming through there.
|
John Canon 450d, EF-S 18-55 IS, 55-250 IS, Raynox DCR250 HQE5 + C80ED & Vista 80s. NexStar Skymax 102 SLT. *** My Astro Blog *** |
|
|
Big Dipper
Events
Hero Member
Posts: 1247
Oxford, UK
|
 |
« Reply #7 on: October 14, 2008, 02:56:25 pm » |
|
We live & learn!
Nice, atmospheric shots gents. I'm not a big 'Moonlover' so don't expect to be out observing or imaging until next week now (skies permitting, of course).
|
Remember:- If all else fails, read the Instruction Manual! 
Andy
|
|
|
|
jgs001
|
|
« Reply #8 on: October 14, 2008, 03:18:51 pm » |
|
Cheers Andy. Well, you'd be in luck here, the forecast is rubbish till at least the weekend.
|
John Canon 450d, EF-S 18-55 IS, 55-250 IS, Raynox DCR250 HQE5 + C80ED & Vista 80s. NexStar Skymax 102 SLT. *** My Astro Blog *** |
|
|
martinastro
Martin Mc Kenna
Global Moderator
Hero Member
Posts: 5182
Maghera, N. Ireland
|
|
« Reply #9 on: October 14, 2008, 04:56:32 pm » |
|
John, Brian, those are very nice Corona images. Nice colours and good job getting the Maria on the Moon to!
|
|
|
|
|
brianb
|
|
« Reply #10 on: October 17, 2008, 12:38:17 am » |
|
A very different corona tonight - much larger and quite vividly coloured (implying small water drops, not surprising in this thin broken alto/stratocumulus)  Canon 40D, 100mm, 1 sec, f/5.6, ISO 400 |
|
|
|
|
|
jgs001
|
|
« Reply #11 on: October 17, 2008, 01:14:02 am » |
|
That's a cracker of an image Brian
|
John Canon 450d, EF-S 18-55 IS, 55-250 IS, Raynox DCR250 HQE5 + C80ED & Vista 80s. NexStar Skymax 102 SLT. *** My Astro Blog *** |
|
|
martinastro
Martin Mc Kenna
Global Moderator
Hero Member
Posts: 5182
Maghera, N. Ireland
|
|
« Reply #12 on: October 17, 2008, 02:52:41 pm » |
|
That is a cracker indeed. Great colours and cloud structure!. Nice one.  |
|
|
|
|
Roman White
|
|
« Reply #13 on: October 17, 2008, 08:20:13 pm » |
|
Brian, I agree with Martin and John (jgs001), it is really good captured (liked the broken clouds). Just to notice: maybe it would be better to move this topic into "Weather&Atmospherics" |
SkyWatcher 130/900mm EQ3, Bresser 76/700mm, 20x90 bino. and other, Olympus SP-550UZ Eclipse & comet chaser, occultation & meteor observer Poltava Astronomy Portal |
|
|
|
