As some of you might recall, I’ve been keeping a (admittedly probably unscientific) spreadsheet of clear skies vs cloudy ones (I’ve had friends and relatives keep a note of sky conditions when I have been away, such as at TSP). I’ve made a note of clear skies, partly cloudy ones, and totally cloudy ones. Clear and partly clear both mean observationally usable ones as, even when partly clear you can still do some observing, even if it’s with a pair of binoculars or half an hour with the scope.

According to my spreadsheet, 2010 had 111 totally clear nights, which is 30% of the total nights of the year. That’s nearly one third which, considering a lot of people think the UK has a largely unfavourable climate is better than you’d think, and that’s despite the horrible harsh and cloudy winter we’ve just had.
Clear and partly clear, added together, comes to 169 nights or 46%. That’s getting on for HALF of the nights here in this part of England being usable for astronomy during 2010. Quite a surprise. Unfortunately, as ever, there’s a caveat – the clearest time is May, June and July when all-night astronomical twilight keeps deep sky observing to a minimum. However, I will make a resolution to use those nights to observe and sketch the brighter DSOs, such as the Messier and brighter NGC nebulae and clusters, rather than just waste them. Maybe I will observe the planets, if any are around, as well. It will be a nice throw back to the time, 19 years ago, when I first got into observing and observed all through the summer twilight – my observing notes throughout the 1990s and early 2000s go right through June and July, no complaints about the twilit nights there!

So far in 2011, 24% of nights have been clear and 29% have been clear or partly clear, mostly during March. I will admit to not taking full advantage of them, mostly because they have coincided with the Moon’s gibbous and full phases.

Looking at all the clear skies we’ve had – and I hope 2011 and beyond follow suit – I am going to make more of an effort to make use of them. It’s not always possible to use every clear night, of course, as life tends to get in the way, as does tiredness and – let’s be honest – laziness, but using half or more would be great.

Yep, Britain has got a reputation for being fairly useless astronomy-wise but – and it does depend on where you live, as we have a varied climate for such a small archipelago – it’s not quite as bad as some people think. Most people work the usual 9am-5pm Monday to Friday routine and, as such, can only observe at weekends and on vacations, so they tend only to look at the sky then. That tends to give the impression that it’s semi-permanently cloudy, as they are only looking through a small window of time so, statistically it’s bound to give a skewed impression.
I am lucky though, in that I live in one of the clearest areas of Britain. The Isle of Wight, just off the south coast, has got one of the highest sunshine totals of anywhere in the country and this also means more clear nights. No, the UK isn’t brilliant and we’d all like 300+ clear nights a year but you’d have to move to somewhere like Arizona for that – although I don’t deny that if the opportunity presented itself I’d be off like a shot!