jaw7509@ritcv.UUCP (John White) (10/15/86)
<CHOMP>
I hate to taunt you all if this is not true, but I seem to
remember reading that at a certain time, on a certain day, once a year,
the top edge of a crater on the moon's dark side is visible. If this is
true and anyone knows about it, (i.e. what day and time), could they
please pass the info on to me. I've always wanted to see this event, but
forgot to save the story (if indeed I did read it).
Thanks in advance,
Whitey Johnson.paula@bcsaic.UUCP (paul allen) (10/18/86)
> I hate to taunt you all if this is not true, but I seem to >remember reading that at a certain time, on a certain day, once a year, >the top edge of a crater on the moon's dark side is visible. If this is >true and anyone knows about it, (i.e. what day and time), could they >please pass the info on to me. I've always wanted to see this event, but >forgot to save the story (if indeed I did read it). > > Thanks in advance, > Whitey Johnson. We can actually see somewhat more than 50% of the moon's surface from the Earth because the moon appears to wobble back and forth a little bit as it orbits around us. I don't think the period of the wobble is as long as a year, though. Why don't you take your telescope out in your backyard and watch the moon regularly for a few months? If you make sketches (or take pictures), I bet you'll be able to determine the period. Have fun! Paul Allen -- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Paul L. Allen Boeing Computer Services Artificial Intelligence Center ...!uw-beaver!ssc-vax!bcsaic!paula
demillo@uwmacc.UUCP (Rob DeMillo) (10/22/86)
In article <90@ritcv.UUCP> jaw7509@ritcv.UUCP (John White) writes: > > I hate to taunt you all if this is not true, but I seem to >remember reading that at a certain time, on a certain day, once a year, >the top edge of a crater on the moon's dark side is visible. If this is >true and anyone knows about it, (i.e. what day and time), could they >please pass the info on to me. I've always wanted to see this event, but >forgot to save the story (if indeed I did read it). > > Whitey Johnson. The lunar revolutions are not *exactly* resonant locked with the earth's. The result is that about an additional 5% of the moon (2.5% on the east limb, and 2.5% on the west limb) will periodically be shown throughout the year. Although this is not much, it does allow for certain craters and mountain ranges to "peep thru" to viewer's on the earth. Since the change is, of course, gradually taking place as the year passes, I doubt that this "mystery crater" *pops* into view on a given night/time. Although it is entirely possible that an *optimal* day/time was given... -- --- Rob DeMillo Madison Academic Computer Center usenet: {ihnp4,harvard,seismo,topaz,decvax}!uwvax!uwmacc!demillo ARPA: demillo@unix.macc.wisc.edu (now isn't that easier?) ---------------------------------------- "I am not so sure what you want me for! 'War Games' Either your machine is a - Crosby, Stills and Nash fool, or me..."
robertd@ncoast.UUCP (Robert DeMarco) (10/23/86)
Sorry, This is a test... Im having trouble getting this message upthier! :wq
dsmith@hplabsc.UUCP (David Smith) (10/24/86)
In article <394@uwmacc.UUCP>, demillo@uwmacc.UUCP (Rob DeMillo) writes: > In article <90@ritcv.UUCP> jaw7509@ritcv.UUCP (John White) writes: > > > >...remember reading that at a certain time, on a certain day, once a year, > >the top edge of a crater on the moon's dark side is visible. > > The lunar revolutions are not *exactly* resonant locked with the earth's. > The result is that about an additional 5% of the moon (2.5% on the east > limb, and 2.5% on the west limb) will periodically be shown throughout the > year. Although this is not much, it does allow for certain craters and > mountain ranges to "peep thru" to viewer's on the earth. > > Since the change is, of course, gradually taking place as the year passes, > I doubt that this "mystery crater" *pops* into view on a given night/time... Lunar libration has two causes that I am aware of: 1. Its elliptical orbit causes its angular velocity about Earth to vary over a monthly period, whereas its rotation around its own axis is uniform. This causes it to appear to wag from side to side, showing a little more on the east, then a little more on the west. 2. Its rotational axis is not normal to its geocentric orbit plane. Therefore, over a month's time, it will nod its poles alternately toward and away from Earth. At the time of the Apollo 11 flight, I got a poster of the moon from a bank. It showed the limits of earthbound observation, and stated that libration causes 59% of the lunar surface to be visible from Earth. So what are the yearly cycles that two posters have referred to? David Smith