If a rogue planet entered our Solar System and push our (Earth's) orbit away from the Sun? What would happen to Earth on an environmental scale?


closed as unclear what you're asking by GrandmasterB, Dan Smolinske, Erik, Ghanima, Maxime Lucas Mar 17 '15 at 12:17

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  • $\begingroup$ We'd be farther from the Sun. How far do you mean? $\endgroup$ – Samuel Mar 17 '15 at 5:21
  • $\begingroup$ Far enough that it could affect Plants and animals. $\endgroup$ – user7960 Mar 17 '15 at 5:35
  • $\begingroup$ Ok, it would affect plants and animals... I'm unclear on what your question is, it seems you've answered it. $\endgroup$ – Samuel Mar 17 '15 at 5:43

Too vague. You need to think a bit about that phrase "pushes earths orbit".

Earths orbit isn't an object one shoves a distance, it's a gravitational relationship. So what does Earth's new trajectory look like? And what other effects have happened? Because the force needed to change a planets trajectory significantly, are quite large ;-)

So for example, did it "push earths orbit" by hitting earth physically? If so, probably environmental effects would be everything from a return to molten magma world, through to shattering the planet. Pretty major environmental effects, eh? Or did it just nudge it gravitationally? Still could have that kind of effect, because the forces holding a planet together aren't infinite. What time scale did this happen over ("pushes" could imply gradual gravitational influence over millions of years, as well as near collision over a few hours). Does earth have a much more elongated orbit now, or still a circular one, and what path? Is Earth's new orbit long term stable or does it cross other substantial bodies that influence or eclipse where they didn't before?

More subtle consequences - what happened to the moon? That tends to be major for the environment. What happened to the new planet itself?

Last, the 3 body problem isn't analytically solvable, so the few-thousand body problem of our real system is less so. That means predictions are hard to make. One prediction that seems likely is that anything that substantially shifts our orbit in a relatively short event probably isn't going to leave many humans alive to worry about carbon emissions ;)

A lot or nothing could happen, depending on all these things. Your call!

  • $\begingroup$ Another point worth making, is that the planets are in a delicate balance of stability. Any additional planet (which by definition, entering the solar system) at escape velocity, would need to significantly affect the other planets to lose enough velocity to be able to be captured by the sun. Most likely it would send 1 or more planets into a chaotic orbit, ending with a planet being ejected. $\endgroup$ – Aron Mar 17 '15 at 7:02

If the Earth's orbit becomes wider, it gets cooler. We may be able to offset that some with adding more greenhouse gasses to our atmosphere.

But if Earth is perturbed, its orbit is likely to be more elliptical than it is now. During part of the year, the Earth would be significantly warmer than at other times -- though not necessarily warmer than it is now.

We could lose the moon and, with it, most of our tides. We'd still have some tides from the sun, but those are already weaker than our lunar tides, and would be weaker still as we moved away from the sun. Animals depending on the tides would suffer. The moon also helps stabilize Earrh's axis of rotation, and over geological scales our seasons could get far more severe at times, maybe even rendering the Earh virtually uninhabitable.

Our year would be longer. Animals and plants that just make it through the winter now might very well die off in large numbers due to the longer winters.

And if our moon did become another body is Earth's orbit, I think Earth would be reclassified as a "dwarf planet," and the pro-Pluto crowd would, at long last, have their revenge.

  • $\begingroup$ +1 For the revenge of the pro-Pluto crowd. That would make a hilarious story. $\endgroup$ – Erik Mar 17 '15 at 8:37


Earth is in what most people call "the Goldilocks Zone" because the temperature of our planet (and the energy we get from the sun) results in a planet that is not too warm, and not too cold. The formal name of this is the Circumstellar Habitable Zone. Every star system, in theory, has one.

For our particular solar system, the estimates on the inner and outer boundary of the goldilocks zone is actually quite large. It looks like most conservative estimates place the edges around .99 to 1.3 AU. (Remember that 1 AU is the average distance from the earth to the sun.)

If this planet knocked us further away, outside of our habitable zone, things would cool down considerably. To the point where all the water would start freezing. That is bad-news bears for most life on earth. That would be the end of you and me, but some of those deep-sea thermal vent communities may carry on, oblivious to the freezing doom on the surface. Vsauce talks about these communities in a video, with more eloquence and entertainment than I can muster here.

Otherwise, if we stay within the habitable zone, get ready for people to talk more about global cooling. We would get thrown into an ice-age, despite the fact that we are geologically coming out of one. We would also need to re-think solar energy, because we would get less energy from the sun. Environmentalists may decide to actually start driving inefficient/polluting vehicles just to get the earth warm again!

The environment is a notoriously tricky thing to predict. This is why, despite the amazing increase in computational power available to us, we still cannot predict weather more than a week out. Our planet would likely develop new weather cycles. Perhaps some places would stay the same, but I highly doubt everything would remain as it is now.