We Are Astronomers: interesting fact

[Euan]

I went to see We Are Astronomers in the Planetarium at the Greenwich Observatory last week (which was really amazing and a must see). One thing that stuck in my head was a fact used in it, David Tennant says something like...

The weather in the UK makes it really difficult for Astronomers, the nights are only clear about one quarter of the time

Anyone dispute this? I find it more like 1/5 or 1/6 myself and I monitor the skies like a nutter

[Beulah]

I would agree - I have been out 95% of the clear nights I have been aware of (over a year for example), and only half of them had satisfactory seeing and transparency with only one still night where I was able to see the E and F stars in the Trapezium.

All in all, it did work out to be a quarter of the time, if you are talking completely cloudless nights. It is not clear on the time span that Mr Tennant was speaking of - I'm thinking annual?

[mdstuart]

Abd then there is the moon. When it is up ( about a 1/3 of the time) about 3/4 of the faint objects become invisible!

Mark

[tinvek]

i believe in the 90 / 10 rule

the skies are clear 90% of the nights i'm working and about 10% of the nights i'm not