<p>So, I found a formula for finding the Nodal Precession rate of a satellite here
<a href="https://en.m.wikipedia.org/wiki/Nodal_precession" rel="nofollow noreferrer">https://en.m.wikipedia.org/wiki/Nodal_precession</a></p>
<p>But the thing is, when I pop in all the numbers in the formula on Desmos for Earth, I don't get 18.6 years per revolution of the nodes, which is what I know it is, I get one revolution every 81260 years. Which is definitely wrong. As I said, I know the value it should get is ~18.6 years per nodal revolution.</p>
<p>So, I largely came here to ask, is this formula even valid? Or am I just doing something wrong somewhere?</p>
<p>I copied the formula exactly, and put in all the right values for the Earth-Moon system. Which is why I am left confused and concerned that the formula is just wrong if it is off by that much. The only thing I assumed was that oblateness is defined by:</p>
<p>((a - b) ÷ a)</p>
<p>Is that perhaps what I did wrong?</p>
<p>I got that it precesses by -2.4521097228 * 10^-12 radians per second. Is the formula wrong, or am I just wrong?</p>
<p>Can you please check the veracity of this formula so I can determine with whom lies the mistake.</p>

CC BY-SA 4.0
2024-04-28T19:16:53.193Z
The formula seems to be for calculating nodal precession caused by the oblateness of earth (may be used for a low orbit artificial satellite etc). This precession will also be ‘around’ the earth’s equatorial plane. However, As the same Wikipedia article also states, “…precession of … the Moon is more complex”. There is also a hint in the fact that the 18.6 year period lunar nodal precession happens ‘around’ the ecliptic meaning it must be caused somehow by the sun’s gravity on the earth-moon system. You seemed to have proved that earth’s oblateness has negligible effect on moon’s precession.
anonymous
CC BY-SA 4.0
2024-04-28T19:22:16.563Z
For example I found some discussion [here](https://www.physicsforums.com/threads/what-is-the-cause-of-lunar-nodal-and-apsidal-precession.851208/) that seems to claim that a major component is due to “ the torque exerted on the Earth-Moon angular momentum by the sun” but I’m not completely sure if it’s correct/how to calculate it.
anonymous
<the-moon><precession>
How to find Nodal Precession of a moon
DanceroftheStars
# How to find Nodal Precession of a moon

(Asked by: username_0 on 2024-04-28)

So, I found a formula for finding the Nodal Precession rate of a satellite here
<https://en.m.wikipedia.org/wiki/Nodal_precession>

But the thing is, when I pop in all the numbers in the formula on Desmos for Earth, I don't get 18.6 years per revolution of the nodes, which is what I know it is, I get one revolution every 81260 years. Which is definitely wrong. As I said, I know the value it should get is ~18.6 years per nodal revolution.

So, I largely came here to ask, is this formula even valid? Or am I just doing something wrong somewhere?

I copied the formula exactly, and put in all the right values for the Earth-Moon system. Which is why I am left confused and concerned that the formula is just wrong if it is off by that much. The only thing I assumed was that oblateness is defined by:

((a - b) ÷ a)

Is that perhaps what I did wrong?

I got that it precesses by -2.4521097228 \* 10^-12 radians per second. Is the formula wrong, or am I just wrong?

Can you please check the veracity of this formula so I can determine with whom lies the mistake.

**Tags:** the-moon, precession

> **Comments:**
> **username_1**: The formula seems to be for calculating nodal precession caused by the oblateness of earth (may be used for a low orbit artificial satellite etc). This precession will also be ‘around’ the earth’s equatorial plane. However, As the same Wikipedia article also states, “…precession of … the Moon is more complex”. There is also a hint in the fact that the 18.6 year period lunar nodal precession happens ‘around’ the ecliptic meaning it must be caused somehow by the sun’s gravity on the earth-moon system. You seemed to have proved that earth’s oblateness has negligible effect on moon’s precession.  
> **username_1**: For example I found some discussion [here](https://www.physicsforums.com/threads/what-is-the-cause-of-lunar-nodal-and-apsidal-precession.851208/) that seems to claim that a major component is due to “ the torque exerted on the Earth-Moon angular momentum by the sun” but I’m not completely sure if it’s correct/how to calculate it.  

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## 0 answers

