<p>This is a perspective effect.  We are on a revolving planet, so as the planet rotates, the moon will appear to move slightly with respect to the distant stars. You can see that if you place yourself on the North Pole, then the effect will vanish.</p>
<p>However there are a lot of actual, real oscillations in the Moon's movement. Just not as large on such a small timescale. These are mostly caused by non-uniform gravitational forces from the Sun and Earth (from Greg's comment)</p>

CC BY-SA 4.0
2024-04-08T20:07:24.170Z
2024-04-10T06:08:59.417Z
2024-04-10T06:08:59.417Z
James K
<p>While simulating today's eclipse, I see something I have never noticed or learnt:</p>
<p>Stellarium shows an oscillation of the Moon's trajectory around its orbit as seen from Earth.</p>
<p>Is it real or a Stellarium glitch (I doubt, knowing its quality/accuracy)?</p>
<p>If real, what is the mechanical cause?</p>
<p>Thank you.</p>
<p><a href="https://i.sstatic.net/7nRHw.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/7nRHw.png" alt="stellarium simulation" /></a></p>

CC BY-SA 4.0
2024-04-08T16:38:17.377Z
Can you give some details on how you created that plot?
James K
CC BY-SA 4.0
2024-04-08T19:30:54.053Z
I basically took Stellarium to today, and activated the Show Orbits and the Show Trails options.
Cingonius Varro
CC BY-SA 4.0
2024-04-08T19:39:14.330Z
It's probably a perspective effect, a result of being on a plant that's revolving   You are seeing lunar parallax
James K
CC BY-SA 4.0
2024-04-08T19:51:17.727Z
I actually just put myself on one pole and the effect vanishes so you are right. Thanks a lot.
Cingonius Varro
CC BY-SA 4.0
2024-04-08T20:07:19.277Z
I'll write it up as an answer then.
James K
CC BY-SA 4.0
2024-04-09T23:39:32.367Z
What you're seeing is exactly as James suggest.  However there are a lot of actual, real oscillations in the Moon's movement.  Just not as large on such a small timescale.  These are mostly caused by non-uniform gravitational forces from the Sun and Earth, and to a lesser extent, other planets.
Greg Miller
<the-moon><orbit><orbital-mechanics><celestial-mechanics><stellarium>
Is the Moon really oscillating around its orbit as seen from Earth?
Cingonius Varro
# Is the Moon really oscillating around its orbit as seen from Earth?

(Asked by: username_0 on 2024-04-08)

While simulating today's eclipse, I see something I have never noticed or learnt:

Stellarium shows an oscillation of the Moon's trajectory around its orbit as seen from Earth.

Is it real or a Stellarium glitch (I doubt, knowing its quality/accuracy)?

If real, what is the mechanical cause?

Thank you.

[![stellarium simulation](https://i.sstatic.net/7nRHw.png)](https://i.sstatic.net/7nRHw.png)

**Tags:** the-moon, orbit, orbital-mechanics, celestial-mechanics, stellarium
> **Comments:**
> **username_1**: Can you give some details on how you created that plot?  
> **username_0**: I basically took Stellarium to today, and activated the Show Orbits and the Show Trails options.  
> **username_1**: It's probably a perspective effect, a result of being on a plant that's revolving   You are seeing lunar parallax  
> **username_0**: I actually just put myself on one pole and the effect vanishes so you are right. Thanks a lot.  
> **username_1**: I'll write it up as an answer then.  
> **username_2**: What you're seeing is exactly as James suggest.  However there are a lot of actual, real oscillations in the Moon's movement.  Just not as large on such a small timescale.  These are mostly caused by non-uniform gravitational forces from the Sun and Earth, and to a lesser extent, other planets.  

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## 1 answers

### Answer by username_1 on 2024-04-08. Score: 5

This is a perspective effect. We are on a revolving planet, so as the planet rotates, the moon will appear to move slightly with respect to the distant stars. You can see that if you place yourself on the North Pole, then the effect will vanish.

However there are a lot of actual, real oscillations in the Moon's movement. Just not as large on such a small timescale. These are mostly caused by non-uniform gravitational forces from the Sun and Earth (from Greg's comment)


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