WMAP mapped tiny fluctuations in the cosmic microwave background (CMB), the ancient light from the early universe, and determined that ordinary atoms make up only 4.6 percent of the universe, while dark matter makes up 24 percent. NASA's Wilkinson Microwave Anisotropy Probe (WMAP) was a spacecraft that operated from 2001 to 2010. "That's progress, but we still have a long way to go to pin down the nature of dark energy." Thanks to Hubble, "If you put in a box all the ways that dark energy might differ from the cosmological constant, that box would now be three times smaller," cosmologist Adam Riess of the Space Telescope Science Institute said in a statement.
NASA's COBE satellite precisely mapped cosmic microwave background. Since its launch, astronomers have continued to use Hubble to make cosmological measurements and refine existing ones. By more accurately measuring the distances to Cepheid variables, stars with a well-defined ratio between their brightness and their pulsations, Hubble helped to refine measurements regarding how the universe is expanding. The mission operated until 1993.Īlthough NASA's Hubble Space Telescope is probably best known for its astounding images, a primary mission was cosmological. Launched in November 1989, NASA's Cosmic Background Explorer (COBE) took precise measurements of radiation across the sky. Hawking also proposed that the universe would not continue on forever but would eventually end. This is similar to Earth although the planet is finite, a person traveling around it would never find the "end" but would instead constantly circle the globe. In recent decades, cosmologist Stephen Hawking determined that the universe itself is not infinite but has a definite size.
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