Are We "Home Alone" in a Galaxy of Billions of Planets?
Over the past few hundred years, Earth has been demoted from its former position as the center of the cosmos. We now know that we are probably merely one of the trillions of planets in the Milky Way galaxy, and one of the smaller ones at that, in an era of rapid scientific discovery. But Earth continues to be exceptional and unique thus far. Despite intensive exploration of the solar system and the thousands of exoplanets that have been confirmed by our increasingly sophisticated telescopes, our planet is still the only one that is known to support life. It's an embarrassment of riches in some ways. From the boiling, corrosive lakes of Yellowstone National Park to the Dry Valleys of Antarctica, Earth's plentiful, tenacious, and ubiquitous lifeforms appear to occupy nearly every nook and cranny. Only a few hundred million years, or an eyeblink in geologic time, may have passed since the formation of Earth from a spinning disc of gas and dust. The evolution of Earth However, Eart...