<blockquote>
  <p>Has the effect of other planets on Earth's orbit been ever measured?</p>
</blockquote>

<p>and </p>

<blockquote>
  <p>...but I'm wondering if it's measurable...</p>
</blockquote>

<p>set up the question in an interesting way because it calls into question (intentionally or not) what kind of <em>measurement</em> would satisfy the question.</p>

<p>The motion of the Earth and other planets can be <em>numerically reproduced</em> with incredible accuracy, and this can only be done when taking into account a large number of planet-planet gravitational effects. Here's an example of a <a href="https://space.stackexchange.com/a/23409/12102">python script</a> doing an approximate calculation and being compared to data from the <a href="https://ssd.jpl.nasa.gov/horizons.cgi" rel="nofollow noreferrer">Horizons web interface</a> which uses data from the <a href="https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory_Development_Ephemeris" rel="nofollow noreferrer">JPL Development ephemerides</a> or DE's which can reproduce the motion of the inner planets to kilometers and outer planets to tens of kilometers.</p>

<p>After the Sun, Jupiter's effect is huge, but interaction between the inner planets is quite big as well, with Venus's and Earth's effects upon each other being quite important. Venus also has a big effect on Mercury as well.</p>

<p>In addition to affecting the inner planets directly, the massive outer planets Jupiter through Neptune move the Sun around by a million kilometers as well, and the inner planets will track the Sun's motion slow movements on the scale of decades or centuries.</p>

<p>But besides showing that simulations match measurements, I don't think there has been any way to perform an <em>actual measurement</em> of the effect of one Planet on another. So the answer to your question could be yes or no depending on how you would like to think of a measurement.</p>

CC BY-SA 4.0
2019-06-25T05:13:40.847Z
2019-06-25T05:26:00.390Z
2019-06-25T05:26:00.390Z
uhoh
<p>For decades, geologists have understood that climate changes are due in part to gradual shifts in the Earth’s orbit, which are caused primarily by Venus for its proximity and Jupiter for its mass, and repeat regularly every 405,000 years. In 2018 a team of geologists and Earth scientists unearthed the first evidence of these changes – sediments and rock core samples that provide a geological record of how and when these changes took place.</p>

<p><a href="https://www.pnas.org/content/115/24/6153" rel="noreferrer">https://www.pnas.org/content/115/24/6153</a>
"Empirical evidence for stability of the 405-kiloyear Jupiter–Venus eccentricity cycle over hundreds of millions of years"</p>

<p>So given the timescales involved, this is as close to measuring this effect as one could expect to get.</p>

CC BY-SA 4.0
2019-06-25T13:30:58.483Z
2019-06-25T13:30:58.483Z
TopCat
<p>Since other planets have their own gravitational pull, I'm wondering if their effect on Earth's orbit has ever been measured? I know that in comparison with the Sun's pull the effect might be rather small, but I'm wondering if it's measurable...</p>

CC BY-SA 4.0
2019-06-24T19:30:12.043Z
To predict accurately the positions of any of the planets, including Earth (something NASA has to do quite well, in order to get space probes there) you have to account for the perturbations caused by the gravity of the other planets.
antlersoft
CC BY-SA 4.0
2019-06-24T19:32:16.073Z
Sure! See, for example [The role of Jupiter in driving Earth's orbital evolution: an update](https://arxiv.org/abs/1511.06043). We can even measure / calculate the effects of the planets on the Sun's position relative to the centre of the mass of the solar system, see the diagram at the top of [this Wikipedia page](https://en.wikipedia.org/wiki/Heliocentric_orbit).
PM 2Ring
CC BY-SA 4.0
2019-06-25T23:24:33.753Z
@PM2Ring I think the most interesting aspect to this question is that it asks if the effect has been *measured*, which is very different from the comments and answers about the effect being *calculated*.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-06-25T23:39:06.437Z
@Chappo Fair point. But measurement and calculation are intertwined to a degree. You can't do pure calculations, since you need measurements of orbital parameters. And you can't do pure measurements because all your reference points are moving. :) The geological evidence of long-term cycles mentioned in TopCat's answer are in one sense measurements, but we need to do calculations to extract the orbital data from them. Etc.
PM 2Ring
CC BY-SA 4.0
2019-06-26T00:13:52.010Z
@PM2Ring Agreed - in fact measurement (observation) is of greatest value when compared to calculation (prediction). Re “reference points are moving”, can we use static celestial reference points, or are the planets’ effects on our orbital path too small?
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-06-26T00:33:43.273Z
@Chappo Yes, traditionally we use the "fixed stars", but they also have proper motion, which can complicate things if you want to measure long term cycles, especially if you use relatively close stars like Alpha Centauri or Sirius. It's not too bad if you use more distant stars, say a few thousand lightyears away, though. We can now use distant galaxies as reference points, but then you have to deal with the rotation of the galaxy, and its motion in the Local Group, as well as the expansion of space.
PM 2Ring
<orbit><planet>
Has the effect of other planets on Earth's orbit been ever measured?
ThePiachu
# Has the effect of other planets on Earth's orbit been ever measured?

(Asked by: username_0 on 2019-06-24)

Since other planets have their own gravitational pull, I'm wondering if their effect on Earth's orbit has ever been measured? I know that in comparison with the Sun's pull the effect might be rather small, but I'm wondering if it's measurable...

**Tags:** orbit, planet

> **Comments:**
> **username_1**: To predict accurately the positions of any of the planets, including Earth (something NASA has to do quite well, in order to get space probes there) you have to account for the perturbations caused by the gravity of the other planets.  
> **username_2**: Sure! See, for example [The role of Jupiter in driving Earth's orbital evolution: an update](https://arxiv.org/abs/1511.06043). We can even measure / calculate the effects of the planets on the Sun's position relative to the centre of the mass of the solar system, see the diagram at the top of [this Wikipedia page](https://en.wikipedia.org/wiki/Heliocentric_orbit).  
> **username_3**: @PM2Ring I think the most interesting aspect to this question is that it asks if the effect has been *measured*, which is very different from the comments and answers about the effect being *calculated*.  
> **username_2**: @Chappo Fair point. But measurement and calculation are intertwined to a degree. You can't do pure calculations, since you need measurements of orbital parameters. And you can't do pure measurements because all your reference points are moving. :) The geological evidence of long-term cycles mentioned in username_5's answer are in one sense measurements, but we need to do calculations to extract the orbital data from them. Etc.  
> **username_3**: @PM2Ring Agreed - in fact measurement (observation) is of greatest value when compared to calculation (prediction). Re “reference points are moving”, can we use static celestial reference points, or are the planets’ effects on our orbital path too small?  
> **username_2**: @Chappo Yes, traditionally we use the "fixed stars", but they also have proper motion, which can complicate things if you want to measure long term cycles, especially if you use relatively close stars like Alpha Centauri or Sirius. It's not too bad if you use more distant stars, say a few thousand lightyears away, though. We can now use distant galaxies as reference points, but then you have to deal with the rotation of the galaxy, and its motion in the Local Group, as well as the expansion of space.  

---

## 2 answers

### Answer by username_5 on 2019-06-25. Score: 7 | Accepted answer

For decades, geologists have understood that climate changes are due in part to gradual shifts in the Earth’s orbit, which are caused primarily by Venus for its proximity and Jupiter for its mass, and repeat regularly every 405,000 years. In 2018 a team of geologists and Earth scientists unearthed the first evidence of these changes – sediments and rock core samples that provide a geological record of how and when these changes took place.

<https://www.pnas.org/content/115/24/6153>
"Empirical evidence for stability of the 405-kiloyear Jupiter–Venus eccentricity cycle over hundreds of millions of years"

So given the timescales involved, this is as close to measuring this effect as one could expect to get.


---

### Answer by username_4 on 2019-06-25. Score: 3

> Has the effect of other planets on Earth's orbit been ever measured?

and

> ...but I'm wondering if it's measurable...

set up the question in an interesting way because it calls into question (intentionally or not) what kind of *measurement* would satisfy the question.

The motion of the Earth and other planets can be *numerically reproduced* with incredible accuracy, and this can only be done when taking into account a large number of planet-planet gravitational effects. Here's an example of a [python script](https://space.stackexchange.com/a/23409/12102) doing an approximate calculation and being compared to data from the [Horizons web interface](https://ssd.jpl.nasa.gov/horizons.cgi) which uses data from the [JPL Development ephemerides](https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory_Development_Ephemeris) or DE's which can reproduce the motion of the inner planets to kilometers and outer planets to tens of kilometers.

After the Sun, Jupiter's effect is huge, but interaction between the inner planets is quite big as well, with Venus's and Earth's effects upon each other being quite important. Venus also has a big effect on Mercury as well.

In addition to affecting the inner planets directly, the massive outer planets Jupiter through Neptune move the Sun around by a million kilometers as well, and the inner planets will track the Sun's motion slow movements on the scale of decades or centuries.

But besides showing that simulations match measurements, I don't think there has been any way to perform an *actual measurement* of the effect of one Planet on another. So the answer to your question could be yes or no depending on how you would like to think of a measurement.


---

