Mars' core formed within just a few million years, scientists say compared to the hundreds of millions or even billions of years that it took for Earth's core to form — it also might smell like rotten eggs.
The challenge in the search for habitable worlds is clear. We need to be able to identify habitable worlds and distinguish between biotic and abiotic processes. Ideally, scientists would do this on entire populations of exoplanets rather than on a case-by-case basis. Exoplanets' natural thermostats might provide a way of doing this.

