A Step-by-Step Guide to Our Solar System’s Demise
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.
The End of Liquid Water (and Life) on Earth
The sun is ever-so-slowly heating up. Today, it’s about 30 percent 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 the rate of the fusion reaction (called the proton-proton chain). This slowly increases the sun’s energy output.
Life as we know it requires liquid water. In order to maintain liquid water on a planet’s surface, there must be a balance between the energy coming in and the energy going out that maintains the right temperature range.
The energy balance is always adjusting itself. If the amount of greenhouse gases in Earth’s atmosphere increases
