The Naked Scientists

The Naked Scientists Forum

Author Topic: What would it take to destabilise Saturn's orbit?  (Read 439 times)

Offline thedoc

  • Forum Admin
  • Administrator
  • Sr. Member
  • *****
  • Posts: 511
  • Thanked: 12 times
    • View Profile
Dorman  Walters Jr asked the Naked Scientists:
   I seen recently that Saturn  stabilized Jupiter's orbit and saved it from becoming a "hot Jupiter". What could de-stabilize Saturn's and send Jupiter back towards the sun? How long would earth last?
What do you think?
« Last Edit: 10/08/2016 14:53:02 by _system »


 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What would it take to destabilise Saturn's orbit?
« Reply #1 on: 10/08/2016 16:09:19 »
Dorman  Walters Jr asked the Naked Scientists:
   I seen recently that Saturn  stabilized Jupiter's orbit and saved it from becoming a "hot Jupiter". What could de-stabilize Saturn's and send Jupiter back towards the sun? How long would earth last?
What do you think?
I never heard that about Jupiter and Saturn. What is the source is this information. And it would take an enormous decrease in the amount of energy of Jupiter to change its orbit so that it falls into the Sun. And Absolutely nothing would happen to the Earth because the addition of Jupiter's mass to the Sun wouldn't change it by very much.
 

Offline Blame

  • Full Member
  • ***
  • Posts: 53
  • Thanked: 1 times
    • View Profile
Re: What would it take to destabilise Saturn's orbit?
« Reply #2 on: 10/08/2016 18:46:15 »
Saturn is, well, a little on the large size for shoving out of the way. Can't see much short of another gas giant doing it and that just transfers the problem as they are all quite happy orbiting where they are.

There are a fair number of MACHOs out there somewhere but non close or we would have spotted it. Perhaps a distant one might wonder in a few hundred million years from now for a sunbath and use its elbows to make room. Don't hold your breath.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4101
  • Thanked: 245 times
    • View Profile
Re: What would it take to destabilise Saturn's orbit?
« Reply #3 on: 11/08/2016 12:40:18 »
Quote from: Dorman  Walters Jr
What could ... send Jupiter back towards the sun?
When you simulate a planetary system by placing planets in various orbits around their star, moving with different velocities, it is common to find two planets passing close to each other and interacting via gravitation. One slows down, and drops into a lower orbit, while the other one moves into a higher orbit; both orbits are somewhat elliptical.

After a few close passes, it is not unusual to find the smaller planet thrown right out of the system into the blackness of interstellar space, or thrown into the fires of the star. The planets shuffle around again, and may later have another chaotic episode, with planets changing positions or even colliding.

Recent discoveries of exoplanets have revealed a large number of Jupiter-sized planets orbiting close to their star - but it is thought that these planets must have formed a long way from the star. Maybe they ejected some large planets from their star, with the "Hot Jupiter" coming into a close orbit around its star?

For this to happen in our Solar System, Jupiter would have to throw out some massive planets that are currently inside its orbit - but there is only the asteroid belt, and small planets like Mars and Earth - not massive enough to make a big change in its orbit.

It is impossible to "run the clock backwards" and be certain about what the Solar System looked like in the past; even the smallest measurement error results in big errors over millions of years - not to mention the fact that these calculations cannot detect lost planets.

But astronomers can run many simulations of how different planetary systems could form, and come to some general conclusions from simulations that produce something like our Solar System.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4101
  • Thanked: 245 times
    • View Profile
Re: What would it take to destabilise Saturn's orbit?
« Reply #4 on: 11/08/2016 22:32:05 »
Quote from: Dorman  Walters Jr
What would it take to destabilise Saturn's orbit?
It is possible that our Solar System could have an encounter with an unknown large object from outside the Solar System (or a planet on a long-period elliptical orbit, previously thrown far from the Sun). But if it's currently unknown, we can't currently predict it.

The most likely interaction would be for Saturn to get into an orbital resonance with Jupiter, and to be dropped into the inner Solar System.

The planets are always trading angular momentum with each other, which changes their orbital radius and eccentricity over time. Over tens of thousands of years, these form the Milankovitch cycles on Earth. But they aren't true cycles, because the planetary orbits never quite come back to where they were before.

Their orbits can get synchronized (eg 2 orbits of 1 planet = 1 orbit of an adjacent planet). This means that these planets have regular tugs on each other, in a consistent directions, and can result in dramatic changes in orbits of the planets. This "orbital resonance" can destabilize an orbit, while some other resonances can stabilize orbits (at least for a while)... it's complicated and chaotic.

See: https://en.wikipedia.org/wiki/Milankovitch_cycles
https://en.wikipedia.org/wiki/Orbital_resonance
 

The Naked Scientists Forum

Re: What would it take to destabilise Saturn's orbit?
« Reply #4 on: 11/08/2016 22:32:05 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums