New simulations revised the timescale of our Solar System’s disintegration
By: Absolute Cosmos
Tags: Space, Solar System, Sun, Red Giant, White Dwarf

Our Sun is about 4.5 billion years old. Having exhausted half of its hydrogen or nuclear fuel, it is half way through its life.

In about five billion years from now it will begin to die, expelling huge proportion of its mass before its core contracts into a white dwarf. It will gradually discharge heat until it becomes a dark and dead piece of rock, a thousand trillion years later.

By then the rest of the solar system will be already long gone. As per new simulations by scientists, it will just take hundred billion years for any remaining planet to run off across the Milky Way galaxy, leaving behind the dying Sun.

Scientists have been trying hard to decipher the ultimate fate of our Solar System for quite a long time. They have been long perusing the idea of understanding the long term dynamical stability of the Solar System.

Newton once himself speculated that the mutual interactions between the planets would ultimately make the system unstable.

But here’s the thing, it is not easy as it seems, something which scientists called the N-body problem. It is the problem of forecasting the individual motions of a group (dynamical system) of objects interacting gravitationally with each other.

The larger the number of objects in a group means the more complicated that group is and harder it becomes to predict. This complexity makes impossible to predict the orbits of Solar System objects past certain timescales.

Scientists predicted in 1999 that our Solar System would slowly break up over a period of at least a quintillion years.

But these calculations did not take some important factors in consideration that could disrupt Solar System sooner- according to scientists performing new simulations.

First factor- the SUN: In about five billion years as our Sun will die, it will become a red giant eventually engulfing Mercury, Venus and Earth. Then it will expel nearly half of its mass, the remaining white dwarf will be about just fifty four percent of the current solar mass.

This mass loss will weaken the gravitational grip of Sun on the rest of the planets- Mars, Jupiter, Saturn, Uranus and Neptune.

The second factor- as our Solar System orbits the centre of Milky Way, other stars ought to approach close enough to disturb the orbits of the planets once in about every twenty three million years.

As per scientists, if we take the account of solar mass loss and the inflation of the orbits of the outer planets, these encounters will become more dominant. Given sufficient time these flybys will approach close enough to destabilise the rest of the planets.

Taking these factors as additional influences for their calculations, scientists ran ten N-body simulations for the outer planets. Mars was left out to save some money on computation costs as its influence should be no to negligible.

These simulations were divided into two time periods: First- up to the end of solar mass loss. Second- the time period that comes after the solar mass loss.

Running only ten simulations is certainly not the strong measurable example, yet scientists found out that the same scenario was played out each time.

After the Sun becomes a white dwarf, the outer planets have a larger but relatively stable orbits. Gas giants Jupiter and Saturn are captured in a stable 5:2 resonance, meaning for every five times Jupiter orbits around the Sun, Saturn orbits twice.

These swollen orbits and aspects of planetary resonance, makes the system more defenceless by the effects of passing stars.

After thirty billion years, such stellar encounters destabilise the stable orbits forcing a rapid loss of planets. All (except one) planets break off their orbits, running deep into the galaxy, eventually becoming rogue planets.

Last planet remains in orbit for another fifty billion years before being knocked out into space by gravitational interactions with the passing stars.

Finally, by hundred billion years after the Sun becomes a white dwarf, our Solar System is no more. That is notably a shorter time frame than what was proposed in 1999.

However, as per scientists, these results are based on current observations of the local galactic environment and estimates of stellar flybys, and there are chances that both of which may change. So by no means these results can be assumed as final or fixed.

For more information: The Great Inequality and the Dynamical Disintegration of the Outer Solar System

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