"Shimmering" when viewing the Moon

[li'l john]

Hello everyone, I wonder if anyone can tell me what the shimmering effect is I saw on the edge of my view last night when watching the Moon. It looks a bit like evaporation off a hot road surface. Is it because of the quality of the supplies EP's with my scope or is it what people mean when they refer to "bad seeing".

Also I saw (with averted vision) a grey "mist" which turned out to be lots and lots of stars. I don't knoiw what I was looking at (this was my 2nd ever session) but it was about one "outstretched"hand west of Orion and 2 or 3 fingers higher, very high in the sky. Chesking the map in Sky at Night I think it may be Hyades. Unhappily there was quite a bit of patchy cloud and I couldn't recognise anything else nearby.

Many thanks.

[brianb]

what the shimmering effect is I saw on the edge of my view last night when watching the Moon. It looks a bit like evaporation off a hot road surface. Is it because of the quality of the supplies EP's with my scope or is it what people mean when they refer to "bad seeing".

Yes. Caused by turbulence in the atmosphere. Can also be caused by the scope not being properly cooled - "tube currents" caused by heat plumes off the parts that cool more slowly (shouldn't be much of an issue with a 70mm frac though).

Sometimes this happens a lot, sometimes the air is steadier. Basically if stars near the zenith are twinkling madly then you know the seeing is going to be ****.

[li'l john]

Thanks for that BrianB, my scope was out for a good hour before I noticed it so it seems a certainty that it was bad seeing. Once again you've taught me something, thanks very much. I love your rule of thumb!

[JamesM]

When you leave your refractor out to cool down, you might want to remove the diagonal/eyepiece and tilt the front of the scope down a little to help any thermals inside your scope to escape from this available opening. Might help bring your scope to equilibrium a little quicker.

James

[brantuk]

Hi John - from your description it could've been one of the several open clusters around aldeberan. More likely I would guess you happened upon the Pliedes - a very popular and most beautiful wide object (Messier 45). You should be able to see M45 and count around seven stars (I can only make out 6 myself lol). Sometimes it's called the "seven sisters".

Your "shimmering" is bound to have been the "seeing" messing about again lol