What can you see underneath the moon's glare (besides the obvious :D))

[pipnina]

I understand that light pollution ruins views of just about everything. But I also understand that the moon pollutes almost as much as some cities. This leads me to the question: What DSOs can I see when the moon is at full glare? If any!

So far, the only things I've seen through my scope are: Jupiter, venus, mars, Luna, M42 (only the brightest parts mind) and the pleiades (w/o nebulosity).

I have never seen M31 (as much as I'd have liked to) because it's in the thickest part of Plymouth's LP (although Cassiopeia is clearly and entirely visible- it's that little bit higher up)

Given this, do I stand any chance at all of finding any DSOs (besides those mentioned) tonight with the moon at its peak?

If I can't see anything, I'll just look at the moon and jupiter and wibbly wobbly venus again

        ~pipnina

[Qualia]

It's a good question.

Generally I don't observe DSOs when the Moon is too bright and I rarely observe the Moon itself when it's full. Again, with a bright Moon high in the sky, I find deep space viewing quite disappointing and even if I find someting I know I will have to return another darker night to sketch it. In short, planets, double stars and the Moon itself are my targets for moonlit nights.

Around 10-ish I think there's a GRS transit which will be fun

[ronin]

Would suggest a list of several double stars and locate and split them.

Not sure which coloured ones are around, Almaak in Andromeda may be, Albireo is below the horizon, Mizar/Alcor in the plough is easy, Schedar (Alpha Cass) is another that is visible, Beta and Delta Cepheus are another 2 with a colour difference.

[John]

You can make out some of the brighter deep sky objects when a bright moon is in the sky but they are a pale shadow of what they look like when it's not in sky so I feel it's best to concentrate on what can still be seen well under a moonlit sky, ie: double stars as ronin says, planets and the Moon itself.

[Gazabone]

Well, I've just come in from peering between the clouds and I could see M81 and M82 (82 was very faint indeed). I have certainly seen them a whole lot better. Yes, imho the full moon really screws up DSO observing but doesn't stop me trying, still quite good practice at finding my way around the night sky.

[YKSE]

It's certainly harder for hunting DSO under full Moon, but not impossible, I've been out these two nights and got some 10 more new NGC. Brighter Messiers are certainly doable in your 130mm scope, I saw M13, M92 easily in my 8x50mm finderscope.

[neural]

Don't forget planetary nebulae -- the ones with high surface brightness should be fine.

[acey]

If it's a full moon and a clear sky then the best thing is to take a walk in the country at a "dark site" without a torch (you won't need one). You'll see the entire landscape beautifully lit, strongly shadowed, looking a bit like a sunny day seen through dark glasses. The Milky Way will be invisible, and the Moon itself will be dazzling. The idea of aiming a telescope at DSOs will seem pointless.

At a light polluted site the Moon is just another streetlight, making it even harder to see anything. Wait until it's out of the way and see what you can manage then.

[Rusty-Gunn]

Related question... On April 8 at 4:08 Alaska time Saturn will be 2.2° south of the moon. Will the moon's brightness ruin my chance to view Saturn?

I figure I should be able to see Saturn before the moon moves "near" it, but I'd still like to know. I could wait for April 8 and learn myself, which makes my post pointless, doesn't it? Thanks.

[Joel Shepherd]

Given the likelihood of the clouds parting just as the moon is full, give or take a couple days, you've got to make the best of it. As a relative newbie, I've tried to make the best of it by setting my sights (so to speak) on locating some new targets that I can come back to when the moon is down and properly observe. I don't expect to see well, but if I can work out where M-something or NGC-whatever is lurking then I can save some time the next time there is a dark night because I already know where to look. Obviously, this strategy only works well for relatively bright targets ... then I'm a newbie in a relatively bright area so that's what I have to work with anyway.

-- Joel.

[YKSE]

Acey,

My only trip to my dark site in a full Moon night taught me that lesson, it was just as you described, only bright landscape around you. I didn't have SQM metre to measure it though.

In my light-polluted backyard, full Moon impact seems vary a bit, it is worst when the Moon goes very high, but this full Moon, when it's mostly blocked by my neighbor's house, I got 18.2 MPSAS in zenith, comparing to 18.8 for a half month ago.

Is it possible that full Moon brightens dark sites' open landscape sky more than a light-polluted city sky?

[acey]

Acey,

My only trip to my dark site in a full Moon night taught me that lesson, it was just as you described, only bright landscape around you. I didn't have SQM metre to measure it though.

In my light-polluted backyard, full Moon impact seems vary a bit, it is worst when the Moon goes very high, but this full Moon, when it's mostly blocked by my neighbor's house, I got 18.2 MPSAS in zenith, comparing to 18.8 for a half month ago.

Is it possible that full Moon brightens dark sites' open landscape sky more than a light-polluted city sky?

The Moon sheds the same amount of light regardless of whether there are lights on the ground. What changes is the eye's perception of its effect. A half Moon in daytime shines as brightly as one at night, but in daytime it constitutes a tiny addition to sunlight so is not noticeable - we don't see the Moon casting shadows. At a light polluted site the Moon likewise augments the ambient light, and the extra contribution it makes may be small in relative terms.

The amount of light we get from the Moon depends on its phase and its altitude in the sky. The full Moon is approximately ten times brighter than a half Moon. Lots of different figures are quoted, depends how you measure it, but it's ten to the nearest ten   It's because we're getting sunlight reflected directly at us, rather than at an angle, from the Moon's rough surface. If the Moon is high in the sky it lights up more sky - when it's low at a dark site you have the option of looking in the opposite direction, at the darkest part of sky, without seeing its dazzle in your eye. But when the Moon rises at a dark site it's like a car headlight suddenly shining on you, and a cue to pack up. Just before Moonset is a good time to arrive.

At a dark site its very obvious that the Moon lights up a large area of sky around it; at a light polluted one this is not apparent. The Moon will have an effect on a Sky Quality reading, but the difference between 18 and 19 is a difference between two degrees of not very good. The brightest DSOs should be weakly visible under either circumstance.

Point sources (double stars, open clusters) are a lot less hurt by Moonlight than extended ones (nebulae, galaxies). The effect is a slight loss of limiting magnitude and a greater loss of limiting surface brightness. Planets aren't hurt at all.

Moonlight in the sky is polarised (just like sunlight in daytime) so a theoretical possibility is to use a polarising filter, aiming at the part of sky that is most strongly polarised (ninety degrees from the Moon). I gave it a go once but wasn't particularly impressed with the results.

It is a well known fact that the clearest nights are moonlit ;-) Just one of those things.