End of Our Solar System

Evolution of the Sun during its main sequence lifetime. Each curve shows one of the Sun’s characteristics compared with the current Sun. The red curve shows its luminosity (brightness). Credit: Wikipedia.

This is the 11th and final chapter in the Solar System’s story. It is about the long-term future of the Solar System, which will come to an end in about 100 billion years.

Our Solar System is on its way out. Slowly.

Over the next several billion years, a series of unfortunate events will take place, spanning from the not-so-great to the truly tragic. Afterward, our Solar System will be gone: all of the planets will be lost and the Sun will be a solitary white dwarf. (Pause to wipe away tears).

I will guide us through our Solar System’s future, one step at a time. Since Earth is our home base, I’ll include a key event affecting life on Earth. 

Here are the five steps to come:

1. Earth’s oceans will boil off.
2. The rocky planets’ orbits may go unstable, leading to a potential giant collision between planets.
3. The Sun will become a red giant and swallow the rocky planets.
4. A passing star will trigger a dynamical instability among the remaining planets.
5. A passing star will strip away the final planet.

It is a near certainty that each of these events will happen, with the exception of number 2 (which has only a relatively small probability). But it will take about 100 billion years to reach the end.

Let’s get to it.

1. The end of liquid water (and life) on Earth
The Sun is ever-so-slowly heating up. Today, it’s about 30% brighter than right after it formed. As the Sun converts hydrogen to helium in its core, the mean molecular weight increases, thus increasing the core’s temperature and thus the rate of the fusion reaction (called the proton-proton chain). This slowly increases the Sun’s energy output.  READ MORE...