Jupiter's gravitational pull on the Sun and Earth

[Glenstr]

I was watching a show on one of the science channels a couple of nights ago and I think I heard that Jupiter's gravitational pull on the sun is around half a million miles (or could have been kilometers).

Now, depending on Jupiter's position in relationship to Earths, at any time does it affect the Sun-Earth distance?

For example, if it happened that Jupiter was at opposition at the same time we were at perihelion would the distance between Earth & the Sun be a little less than the (roughly) 147 million kilometer Earth-Sun distance. Or if Jupiter is at conjunction is our distance increased? Or does the sun just pull/push us along at roughly the same distance, regardless of what Jupiter's effect on it is? thanks.

 

[Drakkith]

Now, depending on Jupiter's position in relationship to Earths, at any time does it affect the Sun-Earth distance?

Absolutely. Earth's orbit is affected by all the objects in the solar system, Jupiter included.

For example, if it happened that Jupiter was at opposition at the same time we were at perihelion would the distance between Earth & the Sun be a little less than the (roughly) 147 million kilometer Earth-Sun distance.

Good question. I think the net effect of Jupiter's influence is to rotate our orbit over time, termed apsidal precession. I'm not sure of the short term effects, but I believe the distance may be a bit larger at perihelion when Jupiter is in opposition.

 

[Nik_2213]

Jupiter's gravity *will* affect Earth/Moon orbit, albeit over very long time. Precession of nodes, and stuff like that. IIRC, influences of Jupiter & Venus have similar orders of magnitude...

Then you've their contributions to the dynamic equipotential 'Lo Roads'.
https://en.wikipedia.org/wiki/Interplanetary_Transport_Network

"...that Jupiter's gravitational pull on the sun is around half a million miles (or could have been kilometers)."
I fear you've misheard. As it stands, that makes no sense. Anyone figure what was meant ??

 

[256bits]

"...that Jupiter's gravitational pull on the sun is around half a million miles (or could have been kilometers)."
I fear you've misheard. As it stands, that makes no sense. Anyone figure what was meant ??

Best guess ( since the show was not referenced )
barycentre
https://en.wikipedia.org/wiki/Barycenter

Sun/Jupitor barycentre lies close to the sun surface - radius of sun rounded off to 700,000 km, again rounded off to 500,000 miles.

 

[Glenstr]

I wish I could remember the name of the show, I often have one of the science channels on when I'm reading or doing other things, and this was the case here. I will just assume then whatever the show was it was incorrect, since I'm pretty sure it clearly stated that Jupiter actually pulls the sun towards it - this is what drew my attention to it from what I was reading at the time. Perhaps it had something to do with another thing I read where it is believed that Jupiter does not actually orbit the sun the way we think, but instead they orbit one another - kind of like what Nik_2213 says:

 

[Drakkith]

I will just assume then whatever the show was it was incorrect, since I'm pretty sure it clearly stated that Jupiter actually pulls the sun towards it

It does. Well, technically it causes the Sun to orbit about the Sun-Jupiter barycenter.

Perhaps it had something to do with another thing I read where it is believed that Jupiter does not actually orbit the sun the way we think, but instead they orbit one another - kind of like what Nik_2213 says:

Your video is correct. Jupiter orbits around the Sun-Jupiter barycenter. Both the Sun and Jupiter are in motion around this point.

From here: http://spaceplace.nasa.gov/barycenter/en/

In the case of the Earth and the Sun, both bodies orbit around the very center of the mass (similar to center of gravity) between them. This point is called the "barycenter."

Earth and the Sun are "connected" by the gravity pulling them together. It's just like the light end and heavy end of the sledge hammer. Compared to the size of the Sun, though, Earth is about like a flea on a cat! So the center of mass between the Earth and the Sun is almost—but not quite—the very center of the Sun.

Jupiter, on the other hand, is 318 times as massive as Earth. Therefore, the barycenter of Jupiter and the Sun is a bit further from the Sun's center. So, as Jupiter revolves around the Sun, the Sun itself is actually revolving around this slightly off-center point, located just outside its surface.

 

[mfb]

As seen by Jupiter, Sun and Earth are close together - they will both be accelerated towards Jupiter in nearly the same way. The net effect of Jupiter's gravity on Earth's orbit (from the differences in acceleration) is small, and averages out over the course of an orbit. Only small effects like the perihelion precession remain.

 

[sophiecentaur]

The significant Wobble of the Sun, due to Jupiter's high mass is just like the effect that the Moon has on the Earth as it orbits around us.

 

[mfb]

With the moon it is a bit easier, because you can consider the Earth/Moon system together orbiting the Sun. There is no direct analogy for Jupiter's influence, because Earth/Moon do not orbit the Sun/Jupiter barycenter.

 

[sophiecentaur]

The parallel is quite clear, if you are just looking at a two body system. In both cases, the approximation is a fair one as a first stab.

Earth/Moon do not orbit the Sun/Jupiter barycenter.

That's true, because the Earth's orbit passes between the Sun and Jupiter. but it's not very relevant to what happens 1. Between Earth and Moon or 2. Between Sun and Jupiter. Are you not just over-complicating this? Where would we stop?

 

[tony873004]

Here is a solar system barycenter simulation I made. You can delete the planets one-by-one to see what their influence was.
https://twitter.com/tony873004/status/804794860880285696

bit.ly/2gWg9DG

 

[mfb]

Where would we stop?

For an accurate calculation: at an n-body simulation. For a less accurate calculation: assume a period perturbation given by the different gravitational pull of Jupiter and Sun vs. Earth/Moon. For an even less accurate calculation: ignore all those effects and use Kepler ellipses.

 

[sophiecentaur]

For an accurate calculation: at an n-body simulation. For a less accurate calculation: assume a period perturbation given by the different gravitational pull of Jupiter and Sun vs. Earth/Moon. For an even less accurate calculation: ignore all those effects and use Kepler ellipses.

My main point was that the two body situation is probably (/definitely) adequate for starters. The presentation of the multi body situation is guaranteed to scare the casual viewer.

 

[mfb]

OP asked about the influence of a third body, you can't answer that in the two-body system.

 

[sophiecentaur]

Yes. I was getting sidetracked.

 

[Chronos]

Given the sun is about 1000 times more massive than Jupiter, the gravitational effect of Jupiter on the sun is pretty trivial. The sun - Jupiter barycenter is located about 1.07 solar radii from the center of the sun, so it does cause the sun to wobble slightly. That translates to about one arc minute of displacement as viewed from Earth when Jupiter is offset 90 degrees with respect to Earth's position.

 

[Bandersnatch]

That translates to about one arc minute of displacement

Surely, you mean 1/4th of an arc minute.

 

[tony873004]

Now, depending on Jupiter's position in relationship to Earths, at any time does it affect the Sun-Earth distance?

Yes.
The link I provided in post #11 above is of an n-body simulation.
I ran the simulation twice, each time recording the Earth-Sun distance on a daily basis.
In the first simulation, I included the Sun, all planets (Pluto too!), and the Moon.
In the second simulation, I set Jupiter's mass to 0.

I ran it two more times, this time recording the Earth-Moon distance.
Here are graphs of the data.

 

[mfb]

You clearly see the yearly / monthly variation as dominant effect: The presence of Jupiter deforms the orbit a bit. A magic constant position of Jupiter would make the orbit more and more eccentric over time, but as Jupiter's position changes, the effect points in different directions over the 12-year cycle, averaging out.

For Moon/Earth, we have such an averaging effect over 1 year already.

 

[tony873004]

... A magic constant position of Jupiter would make the orbit more and more eccentric over time...

Even more so for the outer planets. Within a thousand years of applying this "magic", Saturn, Uranus, Neptune, and Pluto are all Earth-crossers. Soon after that, they start crashing into the Sun.

Here's a simulation that runs in your browser:
http://orbitsimulator.com/gravitySimulatorCloud/simulations/1480799423788_jupiterStationary3.html
The time-step self-adjusts to handle the close passes and collisions.

 

[RJM]

@Glenstr - I believe the show was/is How The Universe Works. I saw the same episode and am wondering the same thing. If Jupiter's "orbit" around the Sun pulls it (I thought they had said 1million kms) closer to Jupiter then there would be an effect on our temperatures. When the Sun, Earth and Jupiter are all in alignment every 12 years we should expect warmer weather for a period that we are in effect "closer" to the Sun. And thus when we are opposite with Jupiter we would experience colder temperatures.

 

[mfb]

Earth's distance to the Sun varies by 5 million kilometers over a year simply from its eccentricity. It is a bit closer to the Sun when the Northern hemisphere has winter. As result, the seasons tend to be less pronounced there compared to the Southern hemisphere.
This has nothing to do with Jupiter, which pulls on Earth and Sun in nearly the same amount. The position of the Sun relative to the barycenter of the solar system (=its motion due to Jupiter and Saturn) is irrelevant for Earth.

When the Sun, Earth and Jupiter are all in alignment every 12 years

This alignment happens every ~13 months.

 

[Whariwharangi]

Sun Barycenter is an interesting topic. Some of the 3 d graphs are astounding.

There has been some discussion that the sun's barycentric orbit sometimes results in significantly less sunlight hitting the earth. I've not found anything that shows cause for alarm in the immediate future. The greater (much greater) problem is grand solar minima.

Barycenter is just one of a gazillion pieces of evidence to sort through as to why anthropogenic CO2 based global warming hypothesis is rubbish.

 

[Drakkith]

There has been some discussion that the sun's barycentric orbit sometimes results in significantly less sunlight hitting the earth.

That's a bit difficult to believe. The Earth is pulled right along with the Sun, so our orbital distance isn't changing that much.

Barycenter is just one of a gazillion pieces of evidence to sort through as to why anthropogenic CO2 based global warming hypothesis is rubbish.

Please keep those sentiments to yourself. The scientific consensus of climatologists clearly points towards anthropogenic CO2 based global warming. It may turn out that they are wrong, but until the scientific consensus turns the other way talk of it being "rubbish" is unwelcome since we pride ourselves on following the current scientific consensus here at PF. Furthermore, given that climate change is a very polarized issue in the public, discussions about it rarely go well, so we have added it to our list of topics which are not allowed to be discussed without prior approval by the staff. If you have any questions or comments about our rules please feel free to contact myself or another mentor.

 

[mfb]

As discussed before already, the orbit of Earth is very stable, especially over human timescales. The amount of sunlight coming in is well-known and doesn't change notably apart from the regular seasonal variations.

 

[Whariwharangi]

As discussed before already, the orbit of Earth is very stable, especially over human timescales. The amount of sunlight coming in is well-known and doesn't change notably apart from the regular seasonal variations.

Not true. Oh sure, the visible light spectrum, the TSI, is fairly constant. There is a lot more variability in magnetic field, solar wind, IR and UV. Its not just the visible light that affects our climate.

Here is link to discussion about hurricanes and UV. It turns out there is correlation with number and severity of hurricanes with solar minima.

'Evidence linking solar variability with US hurricanes' Hodges and Elsner
http://onlinelibrary.wiley.com/doi/10.1002/joc.2196/pdf

 

[Glenstr]

Sun Barycenter is an interesting topic. Some of the 3 d graphs are astounding.

There has been some discussion that the sun's barycentric orbit sometimes results in significantly less sunlight hitting the earth. I've not found anything that shows cause for alarm in the immediate future. The greater (much greater) problem is grand solar minima.

Barycenter is just one of a gazillion pieces of evidence to sort through as to why anthropogenic CO2 based global warming hypothesis is rubbish.

Although I usually refrain from discussion about AGW anywhere, I have to concur that there is a lot more to it than what the masses are being led to believe. The fact that it has more or less become the equivalent of a politically endorsed religion, the models have been notoriously incorrect, anyone who questions the "science" is blackballed or muzzled, that some proponents want dissenters actually jailed, and we are being fed the line that more taxes will help alleviate the problem just rings alarm bells with me.

Don't even get me started on the validity of "carbon credits", which is the equivalent of paying someone else to diet so you can overeat.

 

[Drakkith]

Thread locked for moderation.

 

[Drakkith]

Since multiple people have gone off topic and several problematic posts have had to be removed, I think this thread has run its course.

Thread will remain locked.