navigation on the moon

[CJ44]

What celestial objects would you use to navigate if you are on the moon?  I am assuming our pole star is not the moon's pole star.  how would the sun appear if you were on the moon?

[miguel87]

I think seeing as we are so close in space the night sky would be exactly the same.

I cant decide about the north star. Perhaps a star 23.5 degrees south of the north star, not sure in which direction tho?

Planet movements might be slightly different for mars and perhaps venus.

Just a guess?

Mike

Edited April 8, 2020 by miguel87

[John]

If you use the freeware planetarium software Stellarium you can see what the sky looks like from many locations other than the Earth.

This is a view from the Moons surface:

[Ruud]

Following John's expample.

The first screenshot is from the Moon's North pole, looking straight up, the second from its South pole. (Note that on the North pole, the cardinal directions are all South. Stellarium is perfect!)

[adyj1]

On 08/04/2020 at 21:58, CJ44 said:

What celestial objects would you use to navigate if you are on the moon?  I am assuming our pole star is not the moon's pole star.  how would the sun appear if you were on the moon?

The way I see it is that in its orbit the earth moves roughly 149 million km* in a six-month period and the location of the pole star doesn't change for us during that journey. The moon is never more than 0.4 million km* from us while we're doing that, and so I therefore assume the distances involved (Polaris is 3 million million million million million km* away) means the difference is imperceptible...

But that is based on schoolboy logic, which has let me down in the past... 😉

Ady

 

* yes, I did have to Google all the distances... 😁 

 

Edit: d'oh, it was never going to be this simple... 😔 - see below

Edited April 10, 2020 by adyj1
Correction

[JamesF]

2 hours ago, adyj1 said:

The way I see it is that in its orbit the earth moves roughly 149 million km* in a six-month period and the location of the pole star doesn't change for us during that journey. The moon is never more than 0.4 million km* from us while we're doing that, and so I therefore assume the distances involved (Polaris is 3 million million million million million km* away) means the difference is imperceptible...

I think that might be true if the Earth and the Moon shared parallel axes of rotation.

However, they don't.  The Moon's axis of rotation is far closer to perpendicular to the plane of the ecliptic than the Earth's.  I think therefore that the Moon's "pole star" should be about twenty degrees away from the Earth's (the Earth's obliquity being twenty-three point mumble degrees).

James

[symmetal]

12 minutes ago, JamesF said:

I think that might be true if the Earth and the Moon shared parallel axes of rotation.

However, they don't.  The Moon's axis of rotation is far closer to perpendicular to the plane of the ecliptic than the Earth's.  I think therefore that the Moon's "pole star" should be about twenty degrees away from the Earth's (the Earth's obliquity being twenty-three point mumble degrees).

James

mumble = 4 😁

Alan

[JamesF]

That picture actually explains it far better than I could have done

James

[Waddensky]

Yes, Polaris is not the pole star on the Moon but as far as the night sky goes, everything looks exactly the same as seen from Earth. The distances to the stars involved are just too large to make a difference on about 400.000 km (remember that Earth travels way larger distances around the Sun through the year). Even the planets are on the same location, maybe with some slight parallax on the nearest planets Mars and Venus but I doubt that it will be visible by the naked eye. The Sun looks the same as seen from here, but without daylight. A mag -26 disk in a pitch black night.

But! The most eye-catching, unsettling difference would be the appearance of the stars. No scintillation, no twinkles, no flickering, just steady, constant, lifeless points of light.

Stellarium is great to visualise this. Software like Celestia or Space Engine allows you to land on any planet (or any star) to observe the night sky from there. Really insightful!

[Paul M]

Imagine the glare with a "full Earth" hanging in the sky! No doubt beautiful but it'll mess up your night vision

Anyway, I see a market for suitably modified EQ mounts. Corrected for sidereal rate and selenographic Lat/Long and you're away!

[Marvin Jenkins]

Now we know why the astronauts that landed on the moon had gold coated vizors. Not far off a welders mask on earth I would imagine.

And to think I am not observing tonight due to the overwhelming full moon as it appears to me on Earth!!!

[johninderby]

1 hour ago, Paul M said:

Imagine the glare with a "full Earth" hanging in the sky! No doubt beautiful but it'll mess up your night vision

Anyway, I see a market for suitably modified EQ mounts. Corrected for sidereal rate and selenographic Lat/Long and you're away!

OK when will the first online remote telescope for hire on the moon be available. 😁😁😁

[adyj1]

4 hours ago, JamesF said:

I think that might be true if the Earth and the Moon shared parallel axes of rotation.

However, they don't.  The Moon's axis of rotation is far closer to perpendicular to the plane of the ecliptic than the Earth's.  I think therefore that the Moon's "pole star" should be about twenty degrees away from the Earth's (the Earth's obliquity being twenty-three point mumble degrees).

James

Aaaaah. I see. They don't spin on perpendicular axes. That's a shame 😉 

+1 new in today's Learning column. Thanks for the explanation.  (and the picture helped a lot :-D)

Ady

[Paul M]

1 hour ago, johninderby said:

OK when will the first online remote telescope for hire on the moon be available. 😁😁😁

I think if you want to pay his rates, Elon Musk could drop a solar powered remote controlled telescope on the Moon within 12 months of you paying your deposit!

Probably take longer to design and build the scope than anything else.

 

[johninderby]

59 minutes ago, Paul M said:

I think if you want to pay his rates, Elon Musk could drop a solar powered remote controlled telescope on the Moon within 12 months of you paying your deposit!

Probably take longer to design and build the scope than anything else.

 

And the service bill when a cable comes loose. 🙀🙀🙀🙀🙀