For now, the thousands of potential exoplanets discovered in the past two years are little more than curvy dips on a graph. Astronomers using the Kepler Space Telescope pick them out by examining the way they blot out their own stars' light as they move through their orbits. But if astronomers could block out the stars themselves, they may be able to see the planets directly.
Humans have been looking to the heavens for as long as we have had stories to tell about them. But the way we look up has come quite far in the past 400 years, since Galileo Galilei first pointed a spyglass to the sky.
In honor of the 400th anniversary of the telescope, Popular Science looks back on the top 10 observatories on Earth and beyond.