The solar system is stable for at least the next 100,000 years

The solar system is stable for at least the next 100,000 years

It’s nice to have a feel-good story every now and then, so here’s one to keep away the existential fear: Earth will probably not be thrown into space for at least 100,000 years. In fact, all the planets in the solar system are safe for that time frame, so there is good news all around, for you and your favorite planetary body.

Maybe it’s worth backing up a bit. The probability that the earth, or any planet, will be pushed off its orbit is always small. As Newtonian physics tells us, an object remains in motion if it is not affected by another force – and for something as large as a planet, a significant force would be required to propel a planet off the track. But there are examples of planetary transformation in the solar system’s own history. One of the most accepted models of solar system formation, the Nice modeldescribes how the outer planets migrated early in the history of the solar system and would have caused havoc on the inner rocky worlds, possibly displaced or even swallow smaller protoplanets in the process.

But now researchers have done it made the mat to show that such a migration is unlikely over the next 100,000 years. Angel Zhivkov and Ivaylo Tounchev from the Department of Mathematics and Informatics at Sofia University in Bulgaria used computer calculations to determine that the planets are likely to remain stable. Their eccentricities (how much their orbit differs from circular ones) will remain small, as will their slope (how far above or below the plane of the solar system they travel). Similarly, the half-major axes (the radius of the longest part of an elliptical orbit) will not change significantly for any of the planets.

The half-major axis in a planetary orbit. Image credit: Sndeep81, Wikimedia Commons.

Even the downgraded dwarf planet Pluto was included in this study, and avid Pluto fans will be happy to know that it, too, is likely to do little more than swing a little over the next 100,000 years.

So what happens after 100,000 years? The further you go in time, the harder the predictions become, because the real universe is always a bit chaotic, but Zhivkov and Tounchev believe that “with simple further reasoning and evaluations … the theorem can be proven in a million years.” There will probably be no problems during that time period either. And if you’re really worried, all it takes is a little extra computing power beyond what was available to scientists, and “the stability of the solar system could be proven for the next five billion years,” they say.

Of course, the model is not perfect. It does not take into account relativistic effects, and mathematics assumes that the planets are point masses, which of course they are not in reality. But perhaps the most conspicuous omission from the calculation is the millions of smaller bodies in the solar system: asteroids, comets and everything in between. On their own, the gravitational effects of these objects are negligible, but as a collective, for billions of years, they could certainly fold around the planets a little. Including them all in the model would be a monumental task, and one with declining returns. There is nothing to keep you awake at night.

A simulation of all known terrestrial objects from January 2018. The solar system is a busy place – fortunately most of the objects are small, with lots of empty space that separates them from us and each other. Credit: NASA / JPL-Caltech.

So Earthlings, Martians and Jovians: take a breath and enjoy the ride. The next 100,000 years around the sun will go smoothly. Do not forget the sunscreen!

Read more:

If you want to read the newspaper yourself, the repression is available at ArXiv.

Functional image: True color representation of the planets. Credit: CactiStaccingCrane, Wikimedia Commons.

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