Gliese 581 C
Four centuries ago, Galileo Galilei ran afoul of the Catholic Church for upholding the idea of a heliocentrism. We’ve since learned that even our Sun isn’t the center of the universe. It’s not even the center of our own galaxy for that matter. Now we’re closer to finding evidence that our solar system isn’t wholly unique in having terrestrial planets.
The discovery of a terrestrial planet in another solar system, some 20 light years away, fills in the edges of our biggest map in some very important ways. And it wasn’t all that long ago that we had a hard time getting a reliable map of someplace right here on Earth! (Really, not long ago at all. The last time I downloaded driving directions to somewhere… but I digress.)
Physicist Steven Hawking has said that in order to survive, the human species must go into space. Finding terrestrial planets outside our own solar system is certainly a step in the right direction, but we shouldn’t get too excited about looking for a westward passage to China just yet. In order to seriously explore the challenges of interstellar travel, we've got to establish a foothold in space right here in our own solar system.