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Walking on the Moon

Moon orbital pattern


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My son asked me if the moon orbits with the rotation of the earth or opposit. I told him from my observations it seems to orbit with the rotation but i wasn't compleatly sure of my answer. So I've been watching theMoon tonight in relation to Venus and they seem to be separating ever so slightly, so i would assume whati told my son was Right. I would just like to make sure?. So if any of you know, Ild love to be 100 percent certain.

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52 minutes ago, michael.h.f.wilkinson said:

Yes, the moon does orbit in the same direction as earth's rotation. There are some retrograde moons in the solar system (Triton is the only big one, AFAIK), and these are probably the result of capture

When you say retrograde, do you mean that they rotate in the opposite direction to the planet. 

OR

Do you mean that they appear at times to be moving backwards as seen from our perspective?. My understanding of retrograde is that as seen from our perspective and position in relation to the object... We can be ahead of it, behind it if imagined to be on the same level plain. This means both Earth and the other object are playing a constant game of cat and mouse, and seems like other object is back tracking on itself. 

Probably made a dog's dinner of explaining retrograde. 

Edited by LukeSkywatcher
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1 minute ago, LukeSkywatcher said:

When you say retrograde, do you mean that they rotate in the opposite direction to the planet. 

OR

Do you mean that they appear at times to be moving backwards as seen from our perspective?. My understanding of retrograde is that as seen from our perspective and position in relation to the object... We can be ahead of it, behind it if imagined to be on the same level plain. This means both Earth and the other object are playing a constant game of cat and mouse, and seems like other object is back tracking on itself. 

Probably made a dog's dinner of explaining retrograde. 

Retrograde moons are those whose orbital motion is opposite to the rotation of the planet

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Got you. So retrograde means backwards or opposite direction. I knew that. I'd never considered it with regards to moons orbiting/rotating around planets...just for planets themselves. 

I've never looked up the actual meaning. Thanks for clarifying.

Edited by LukeSkywatcher
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3 hours ago, LukeSkywatcher said:

Venus and Uranus rotate clockwise. All the other planets rotate counter clockwise. 

Don't ask me why. 

Conservation of angular momentum. The solar system was made from a big cloud of rotating gas and dust,  so anything made from that cloud will retain the same momentum and rotation. 

Venus and Uranus where likely struck by a large planetesimal during the early days, and flipped over on their head and side respectively. 

Edited by rockystar
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19 hours ago, rockystar said:

Conservation of angular momentum. The solar system was made from a big cloud of rotating gas and dust,  so anything made from that cloud will retain the same momentum and rotation. 

Venus and Uranus where likely struck by a large planetesimal during the early days, and flipped over on their head and side respectively. 

I was thinking about collisions. Certainly with Uranus because it's on its side. 

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  • 1 month later...
On ‎28‎/‎05‎/‎2018 at 03:53, Knighty2112 said:

Here’s a graphic to make it clear. This is looking down on the orbit of the earth and moon from the northern plane of the solar system.

D1088C29-C63B-4099-A98C-D23CBFABA1C8.thumb.jpeg.56b482f184d2ddb67a2cec3054228f49.jpeg

If the Earth were stationary it would look like that, but since Earth is also in motion around the Sun, the Moon would actually appear to weave "in and out" , as in these pictures:

moon orbit.jpg

moon_s-shaped_orbit.gif

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  • 3 weeks later...
On 28/05/2018 at 09:50, LukeSkywatcher said:

Got you. So retrograde means backwards or opposite direction. I knew that. I'd never considered it with regards to moons orbiting/rotating around planets...just for planets themselves. 

I've never looked up the actual meaning. Thanks for clarifying.

For the philologically-minded, 'retrograde' is from the Latin 'retrogradus' - 'retro' meaning 'backwards' and 'gradus' meaning 'step'. It means 'going backwards'. There are many other retro- words (retrospective, retrogression, retroactive etc)

Conversely, 'prograde' (Latin - 'step forward') means 'going forward'. (Other pro- words include prognosis, prologue, pronoun etc)

I'll get back in me box now.

 

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