First decent look at moon - what is this?

[Astro78]

well WOW. What a difference a cooled collimated and quality high power lense does on the moon!

Impressive stuff.

There seems to be a strange line towards the top third (bottom in newt) of the moon. It's pretty distinctive slightly away from the darkened edge.

Can anyone else see this is? It looks so out of place, seems perfectly straight, and very thin and dark. .. quite sure it's not a hair as stays on the same position. Best seen around 150x

[Dennis]

Hmm, sounds like you may have been viewing “Rupes Recta”?

Cheers

Dennis

[ngcles]

Hi Trav,

It was almost certainly Rupes Recta in Mare Nubium as Denis has noted. It is otherwise known as the "straight wall" -- a very distinctive feature at 7-8 days into the lunation it was very distinct last night night.

It is a fault-line -- real length is a bit over 100km. In a couple of days time the shadow it casts will disappear as the Sun climbs higher and it will become much, much more difficult to see.

Good catch.

Doh!! I think I just made an admission that I look at the Moon -- that could potentially have me kicked out of the deep-sky observers guild whose members must swear a blood-curdling oath never to look at it.

Best,

Les D
Contributing Editor
AS&T

[Astro78]

Thanks Dennis and Les (hush hush). I'm sure that's it. Cool to know what it's called. Was now able to read a little about it.

To think it's only 2-3 km's wide and to see that from the backyard. Nice.