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Old December 29th 20, 06:24 AM posted to alt.astronomy
Daniel65
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Posts: 75
Default Is the Moon Supposed to "Cartwheel"?

R Kym Horsell wrote on 29/12/20 07:15:
Justin Tyme wrote:
On 12/28/2020 12:19 AM, Daniel65 wrote:
Justin Tyme wrote on 28/12/2020 2:01 am:
By cartwheel, I mean appear to rotate clockwise or counterclockwise
throughout the course of the night? Or, is is supposed to appear
stationary from a fixed point on earth?

A fair question is "Why don't you go outside and look?" My answer is
that I have and while the first few times the moon seemed to stay in
place, the last few times I have looked it had, indeed, appeared to
have rotated 45 degrees or so clockwise over the course of several hours.

I would think that the Moon's Axis always points in the same Galactic
direction as the Earth's Axis. Sort of!! Give or take!!

So, at Moonrise, the Moon's Axis would, effectively, be lieing on the
Earth's Eastern Horizon with the Moon's North Pole pointing towards the
North.

At Moon noon, the Moon's Axis would be directly overhead, with the
Moon's North Pole pointing towards the North.

At Moonset, the Moon's Axis would, effectively, be lieing on the Earth's
Western Horizon with the Moon's North Pole pointing towards the North.


So, let's say I'm in the midwestern US. And at the beginning of the
night the "face" of the moon is in one place: pretty much upright, a
little left of center, "eyes" toward the top. At 3am it's like the moon
is a dial, the eyes are way on the right side as I view it.

I'm just trying to get a handle on this. In the past I have not been
very observant, but I always thought the "face" was in the same place.

...

The horizon is not "horizontal" and verticals from the horizon
are not "vertical". If you judge whether some planet or constellation
is "spinning" by comparing it with the horizon to the East...to the
North....to the West you are misled.

E.g. Orion rises in the east and seems to be laying on one side.


Correct.

During the night it travels to the north and seems to be more or less
upright.


Certainly the case for me, here in the Southern Hemisphere, but, as
Orion is an "Equatorial" Constellation, if Justin is in (high) Northern
Hemisphere, wouldn't Orion seem to be moving across the Southern part of
his sky??

When it sets in the west it seems to lay on the oppsites side.


Yeap!

Same Same for the Moon. The Half that you see above the Eastern Horizon
at "Moonrise" isn't the same half you see above the Western Horizon at
"Moonset".

(In the phases of the Moon, they refer to them as "First Quarter" and
"Last Quarter" don't they??

Yet the universe is not spinning 15 deg per hour.

Unfortunately this topic is a long-time favorite of concern trolls.
When I started reading USENET in the 80s it was a thing.
I'm sure some of the people that made it popular back then
have web pages or youtubes dedicated to them by now.

Can't say I've noticed Justin Tyme here previously (not that I've
particularly been looking), so I was just trying to treat him as a newby
astronomer!
--
Daniel