Eye on the Universe: More Hubble Splendor

This fall, astronauts aboard the space shuttle Atlantis will pay a final visit to the Hubble Space Telescope (HST). They will install new instruments enabling it to peer deeper into space than ever before, and replace aging gyroscopes and batteries to keep it running until at least 2013. For nearly two decades, the orbiting telescope has radioed back to Earth images that have altered our understanding of the universe. The Hubble helped confirm the existence of dark matter: mass that we cannot see, but which nevertheless makes its gravitational in uence visible by bending light itself. It proved the existence of black holes, previously a theoretical concept, and enabled the study of star formation and destruction—supernovae—as never before. The Hubble captured the first evidence that planet formation is common during the birth of stars, and has detected life-forming gas on extrasolar planets. It has provided dramatically improved estimates of the age of the universe, and led scientists to the inescapable conclusion that an unknown force—dark energy—is causing the universe to expand at an accelerating rate.

HSCA’s Peter M. Challis captured this supernova (1994D), an exploding star that detonated in the outer regions of the galaxy. “Supernovae,” says professor of physics and astronomy Christopher M. Stubbs, “are bright enough to be detected halfway across the visible universe, and serve as beacons with which we can measure the history of the expansion of the cosmos.” Hubble observations allowed astron omers to peg the age of the universe at 13.7 billion years, but its images of supernovae also drove them, reluctantly, to an astounding conclusion: the universe is expanding at an increasing rate. A force known as “dark energy,” they theorize, exerts a steady, repulsive power. In the early universe, when objects in space were closer together, gravity partly counteracted dark energy’s influence, slowing the expansion. But over time, the weakening of gravitational forces is causing the expansion to accelerate.

Hundreds more Hubble images appear at here.

From the article Eye on the Universe, in Harvard Magazine.