The Universe Is Getting Bigger

In the 1920s, astronomer Edwin Hubble made the revolutionary discovery that the universe is not static, but rather is expanding. But, it was long thought that the gravity of matter in the universe would slow this expansion or even cause it to contract. In 1998, the Hubble Space Telescope studied very distant supernovas and found that, a long time ago, the universe was expanding more slowly than it is today. This puzzling discovery suggested that an inexplicable force, called dark energy, is driving the accelerating expansion of the universe.