<p>My best guess: <strong>The late periapsis of 1P Halley in 1759</strong>.</p>

<p>In 1705, with the mathematical assistance of Issac Newton, Edmond Halley published <em>Synopsis of the Astronomy of Comets</em> which made the prediction that the comet observed in  1682 had previously been observed in 1531 and 1607 was the same object returning about every 76 years or so.  He included a rough estimation of the gravitational effects of Jupiter and Saturn, and predicted it would return in 1758.</p>

<p>From <a href="https://en.wikipedia.org/wiki/Halley%27s_Comet" rel="nofollow noreferrer">Wikipedia: Halley's Comet</a></p>

<blockquote>
  <p>Halley's prediction of the comet's return proved to be correct,
  although it was not seen until 25 December 1758, by Johann Georg
  Palitzsch, a German farmer and amateur astronomer. It did not pass
  through its perihelion until 13 March 1759, the attraction of Jupiter
  and Saturn having caused a retardation of 618 days. This effect was
  computed prior to its return (with a one-month error to 13 April) by a
  team of three French mathematicians, Alexis Clairaut, Joseph Lalande,
  and Nicole-Reine Lepaute. The confirmation of the comet's return was
  the first time anything other than planets had been shown to orbit the
  Sun. It was also one of the earliest successful tests of Newtonian
  physics, and a clear demonstration of its explanatory power.</p>
</blockquote>

<p>This predates the discovery of Uranus(1781) and Neptune (1846).</p>

CC BY-SA 4.0
2019-03-02T01:25:16.413Z
Wow, thanks. Now that's going to be an interesting work to somehow find and read. *This is great!*
uhoh
CC BY-SA 4.0
2019-03-02T03:22:12.143Z
+1. Great contribution notovny, and welcome to Astronomy.SE :-)
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-03-11T04:02:55.010Z
I've just asked [What calculation did Halley do to estimate the effects of Jupiter and Saturn on Halley's comet's return in 1785?](https://hsm.stackexchange.com/q/8369/3869)
uhoh
CC BY-SA 4.0
2019-08-26T14:36:13.887Z
I'm not sure why I haven't accepted until now, but *I'm accepting now!* Thanks!
uhoh
CC BY-SA 4.0
2019-03-02T01:21:09.920Z
2019-03-02T01:21:09.920Z
notovny
<p>Answers to the question <a href="https://astronomy.stackexchange.com/q/4834/7982">How did Kepler determine the orbital period of Mars?</a> describing careful observations centuries ago got me thinking.</p>

<p><strong>Question:</strong> What was the first analysis of observations that directly demonstrated that the movement of a planet <em>or asteroid</em> in its orbit was affected by gravitational attraction by another planet?</p>

<p>I don't mean inferences based on the spacing of orbits, I'm thinking of detailed positional measurements; something like <em>planet/asteroid A</em> was X kilometers or Y arcseconds away from it's predicted position and it couldn't be accounted for if not for the gravitational effects of <em>planet B</em>.</p>

<p>I am not sure if <a href="https://astronomy.stackexchange.com/q/29742/7982">First observation that the Sun and Jupiter (and friends) move around a common barycenter?</a> is a completely separate question, or if this confirmation happened all at once, but I've currently asked it separately.</p>

CC BY-SA 4.0
2019-02-25T04:26:43.397Z
To what I know I think there were two of these, but idk which came first:

1) Uranus was affected by something. Then two scientists in separate countries mathematically calculated its position.

2)The same astronomer that mathematically calculated Neptune **first** proposed another possible planet Vulcan, and mathematical calculated its orbit[inside Mercury's, affecting Mercury's orbit].
Max0815
CC BY-SA 4.0
2019-02-25T04:39:35.990Z
@Max0815 They should be correct. I'll edit: "directly demonstrated" → "directly and correctly demonstrated"
uhoh
CC BY-SA 4.0
2019-02-28T04:45:37.750Z
[We can determine the masses of planets if they have moons.](https://www.scientificamerican.com/article/how-do-scientists-measure/) For Mercury and Venus (pre space age) we had to deduce their masses from perturbations by other planets. I guess this would be among the earliest studies of this phenomenon. See:[Determination of planetary mass and radius.](https://hsm.stackexchange.com/questions/6020/determination-of-planetary-mass-and-radius/6026#6026), [Determination of Masses of Mercury and Venus from Observations of Five Minor Planets](http://adsabs.harvard.edu/full/1995AcA....45..665S).
Keith McClary
CC BY-SA 4.0
2019-02-28T04:55:50.063Z
@KeithMcClary Great! Then I think that citing the first mass deduction of Mercury and/or Venus (or even possibly of Earth) based on perturbations by other planets would be an excellent answer to my question!
uhoh
CC BY-SA 4.0
2019-02-28T05:16:40.813Z
@KeithMcClary oh, I see you've [mentioned it before](https://astronomy.stackexchange.com/a/29757/7982) and not reposted as a comment. Yes this will take some digging to figure out. Thanks for the comment!  *update:* It seems that since Jupiter is the solar system's gravitational bully, it's effect on the orbit of other planets would have been noticed very early. Also after thinking about your [linked article](http://adsabs.harvard.edu/full/1995AcA....45..665S) I've decided to include the effects of planets on asteroids as well.
uhoh
CC BY-SA 4.0
2019-02-28T05:28:02.420Z
It seems to be a complicated tale: https://www.google.ca/search?q=Leverrier+mass+venus , http://www.gsjournal.net/Science-Journal/search_results?cx=partner-pub-0300834755212870%3A51h16sucj21&cof=FORID%3A11&ie=ISO-8859-1&q=Leverrier+&sa=Search Someone on hsm.SE might know this.
Keith McClary
CC BY-SA 4.0
2019-02-28T05:31:42.023Z
@KeithMcClary yes, the more I think about it, the more I see what you mean. I'm now [thinking of moving it](https://hsm.stackexchange.com/questions/6020/determination-of-planetary-mass-and-radius/6026#comment15952_6026) there now.
uhoh
<gravity><solar-system><history>
First observation that the movement of a planet or asteroid in its orbit was affected by another planet?
uhoh
# First observation that the movement of a planet or asteroid in its orbit was affected by another planet?

(Asked by: username_0 on 2019-02-25)

Answers to the question [How did Kepler determine the orbital period of Mars?](https://astronomy.stackexchange.com/q/4834/7982) describing careful observations centuries ago got me thinking.

**Question:** What was the first analysis of observations that directly demonstrated that the movement of a planet *or asteroid* in its orbit was affected by gravitational attraction by another planet?

I don't mean inferences based on the spacing of orbits, I'm thinking of detailed positional measurements; something like *planet/asteroid A* was X kilometers or Y arcseconds away from it's predicted position and it couldn't be accounted for if not for the gravitational effects of *planet B*.

I am not sure if [First observation that the Sun and Jupiter (and friends) move around a common barycenter?](https://astronomy.stackexchange.com/q/29742/7982) is a completely separate question, or if this confirmation happened all at once, but I've currently asked it separately.

**Tags:** gravity, solar-system, history

> **Comments:**
> **username_1**: To what I know I think there were two of these, but idk which came first:  1) Uranus was affected by something. Then two scientists in separate countries mathematically calculated its position.  2)The same astronomer that mathematically calculated Neptune **first** proposed another possible planet Vulcan, and mathematical calculated its orbit[inside Mercury's, affecting Mercury's orbit].  
> **username_0**: @username_1 They should be correct. I'll edit: "directly demonstrated" → "directly and correctly demonstrated"  
> **username_2**: [We can determine the masses of planets if they have moons.](https://www.scientificamerican.com/article/how-do-scientists-measure/) For Mercury and Venus (pre space age) we had to deduce their masses from perturbations by other planets. I guess this would be among the earliest studies of this phenomenon. See:[Determination of planetary mass and radius.](https://hsm.stackexchange.com/questions/6020/determination-of-planetary-mass-and-radius/6026#6026), [Determination of Masses of Mercury and Venus from Observations of Five Minor Planets](http://adsabs.harvard.edu/full/1995AcA....45..665S).  
> **username_0**: @username_2 Great! Then I think that citing the first mass deduction of Mercury and/or Venus (or even possibly of Earth) based on perturbations by other planets would be an excellent answer to my question!  
> **username_0**: @username_2 oh, I see you've [mentioned it before](https://astronomy.stackexchange.com/a/29757/7982) and not reposted as a comment. Yes this will take some digging to figure out. Thanks for the comment!  *update:* It seems that since Jupiter is the solar system's gravitational bully, it's effect on the orbit of other planets would have been noticed very early. Also after thinking about your [linked article](http://adsabs.harvard.edu/full/1995AcA....45..665S) I've decided to include the effects of planets on asteroids as well.  
> **username_2**: It seems to be a complicated tale: https://www.google.ca/search?q=Leverrier+mass+venus , http://www.gsjournal.net/Science-Journal/search_results?cx=partner-pub-0300834755212870%3A51h16sucj21&cof=FORID%3A11&ie=ISO-8859-1&q=Leverrier+&sa=Search Someone on hsm.SE might know this.  
> **username_0**: @username_2 yes, the more I think about it, the more I see what you mean. I'm now [thinking of moving it](https://hsm.stackexchange.com/questions/6020/determination-of-planetary-mass-and-radius/6026#comment15952_6026) there now.  

---

## 1 answers

### Answer by username_3 on 2019-03-02. Score: 4 | Accepted answer

My best guess: **The late periapsis of 1P Halley in 1759**.

In 1705, with the mathematical assistance of Issac Newton, Edmond Halley published *Synopsis of the Astronomy of Comets* which made the prediction that the comet observed in 1682 had previously been observed in 1531 and 1607 was the same object returning about every 76 years or so. He included a rough estimation of the gravitational effects of Jupiter and Saturn, and predicted it would return in 1758.

From [Wikipedia: Halley's Comet](https://en.wikipedia.org/wiki/Halley%27s_Comet)

> Halley's prediction of the comet's return proved to be correct,
> although it was not seen until 25 December 1758, by Johann Georg
> Palitzsch, a German farmer and amateur astronomer. It did not pass
> through its perihelion until 13 March 1759, the attraction of Jupiter
> and Saturn having caused a retardation of 618 days. This effect was
> computed prior to its return (with a one-month error to 13 April) by a
> team of three French mathematicians, Alexis Clairaut, Joseph Lalande,
> and Nicole-Reine Lepaute. The confirmation of the comet's return was
> the first time anything other than planets had been shown to orbit the
> Sun. It was also one of the earliest successful tests of Newtonian
> physics, and a clear demonstration of its explanatory power.

This predates the discovery of Uranus(1781) and Neptune (1846).

> **Comments:**
> **username_0**: Wow, thanks. Now that's going to be an interesting work to somehow find and read. *This is great!*  
> **username_4**: +1. Great contribution username_3, and welcome to Astronomy.SE :-)  
> **username_0**: I've just asked [What calculation did Halley do to estimate the effects of Jupiter and Saturn on Halley's comet's return in 1785?](https://hsm.stackexchange.com/q/8369/3869)  
> **username_0**: I'm not sure why I haven't accepted until now, but *I'm accepting now!* Thanks!  

---

