Some questions on Lunar observation

[prasadka]

Hi

Had a very good night yesterday, observing the moon into the little hours. I noticed that, what you see over a period of time as craters, seems to develop into outwardly projected mountains visually, than remain seen as craters. What could be the reason for this?

Also,I wear glasses constantly, but tried an experiment last night removing the glasses- I could still see clearly, whereas I struggle to read from a distance without glasses on.. can someone tell me why?

Cheers,

Prasad

[GazOC]

Also,I wear glasses constantly, but tried an experiment last night removing the glasses- I could still see clearly, whereas I struggle to read from a distance without glasses on.. can someone tell me why?

Cheers,

Prasad

By focusing the telescope your're just letting the scope do the job of the glasses. I'm in the same boat, blind as a bat after 20 foot but I never wear my contact lenses to observe.

[Andrew*]

I rarely observe with my glasses. It's a bit annoying to put them on to look at the sky and lift them up to look in the eyepiece, but I find I can see much better without the glasses. Of course I have to focus it to suit my eyesight.

the crater/mountain thing is a common optical illusion. Looking at a picture of a cube, you could just as well be looking at the inside of a box:

HTH

Andrew

[prasadka]

Hi..

Thought as much, but did not realise that would be true for viewing the moon either. It probably was just my depth perception.

Thanks anyways..

Regards,

Prasad

[Talitha]

The illusion has also been reported by people viewing lunar images. From what I understand it has nothing to do with our eyesight or whether or not we wear glasses... no idea what causes it.

[lunator]

Prasad

The reason for the apparent change between craters and mountains is the brain perceives that the light is coming from one direction when the actual light source is from the opposite direction.

I was once looking at an image of a Martian crater and when I first looked at it appeared as a dome lit from the top right, but after a few moments it became a crater lit from the bottom left.

Cheers

Ian

[Azelfafage]

So far, circumstances have conspired to make me miss any chance of observing the moon with my new scope - I've completely missed the last lunation

Had to confine myself to DSO's (2 decent sessions so far) - so of course can't comment on the crater thingy but I'd like to add on the subject of eyesight, that without specs, my right eye seems better than my left when the scope is focused ("better" in the sense of star=point of light instead of small blob), and also sensitivity to faint objects (such as M82).

I'll be very interested to test my eyes on the lunar landscape when I (eventually) get the chance - I may find that it doesn't matter which eye is used

regards,

A

[proflight2000]

Seeing as my work has basically changed my eyesight from 20/20 vision to seeing nothing 4 inches in front of me, the telescope actually gives my eyes a break from them being iritated, the optician gave me odd looks when i mentioned it, but seeing as he was so close to my face i couldnt see him that well anyway.

[The Warthog]

For some reason the craters on the east side of Mare Crisium often appear as domes to me when the shadow of the terminator is just reaching them after the full moon. Same optical illusion, but this is the only place I can remember seeing it.