Living on a Pale Blue Dot

Over time, the Earth’s habitability for human beings has changed tremendously, despite the mild, slow changes in the Sun’s intensity and the slight shifts in Earth’s orbit: cycles of “Snowball Earth” put mile-deep glaciers all over the Earth, even into the tropics, whereas longer ago the atmosphere was completely different and impossible for humans to survive in. The interdisciplinary science of planetary habitability is revealing the intrinsic duality of processes that are both beneficial and detrimental to life: sunlight, magnetism, volcanism, chemical weathering, asteroid impacts, and even life around us. With so many processes, the balancing act of our comfortable planet is remarkable, perhaps unique. Ultimately, nature will destroy our habitable home, but not likely for a very, very long time, provided we ourselves do not cause things to derail.