Astrophysics for People in a Hurry (Astrophysics for People in a Hurry Series)

by Neil deGrasse Tyson

We do not simply live in this universe. The universe lives within us. That being said, we may not even be of this Earth. Several separate lines of research, when considered together, have forced investigators to reassess who we think we are and where we think we came from. As we’ve already seen, when a large asteroid strikes a planet, the surrounding areas can recoil from the impact energy, catapulting rocks into space. From there, they can travel to—and land on—other planetary surfaces. Second, microorganisms can be hardy. Extremophiles on Earth can survive wide ranges of temperature, pressure, and radiation encountered during space travel. If the rocky ejecta from an impact hails from a planet with life, then microscopic fauna could have stowed away in the rocks’ nooks and crannies. Third, recent evidence suggests that shortly after the formation of our solar system, Mars was wet, and perhaps fertile, even before Earth was. Collectively, these findings tell us it’s conceivable that life began on Mars and later seeded life on Earth, a process known as panspermia. So all Earthlings might—just might—be descendants of Martians.