National Aeronautics and
Space Administration
Goddard Space Flight Center

COBE: Revealing Secrets of the Big Bang

The Cosmic Background Explorer (COBE) spacecraft has been engaged in some of the most exciting work ever done in the study of the Universe. It has peered back in time some 15 billion years to very nearly the point of creation, which scientists believe began with a catastrophic explosion known as the Big Bang. Launched in 1989 and managed by NASA's Goddard Space Flight Center in Greenbelt, Md., COBE has uncovered landmark evidence to support the Big Bang theory of an expanding Universe. COBE was designed and built in house at the Goddard Center. Science researchers continue to do analysis on data received from the spacecraft.

A Single Explosion

COBE's first test of the theory showed that 99.97 percent of the energy of the Universe was released in the first year after the Big Bang. This suggests that only one explosion "the Big Bang" created the Universe. NASA researchers determined this by measuring the spectrum of cosmic background radiation, which is the Big Bang afterglow that exists all around us. According to predictions, the background radiation should have a "blackbody" spectrum unless there were major energy releases more than a year after the explosion. COBE found this spectrum precisely as it was predicted.

The Irregular Universe

COBE's second test of the Big Bang theory found the reason why the Universe is composed of clusters of galaxies separated by vast stretches of empty space. These are irregularities, detectable by their slight temperature differences, in the structure of the Big Bang explosion. These irregularities are believed to have caused the clumping of matter in some places, but not in others. In areas where matter clumped, galaxies filled with stars, planets and other objects slowly took shape over billions of years. In areas where matter did not clump, empty space was left. COBE verified this scenario by detecting the tiny temperature differences that linger as evidence of the irregularities in the initial explosion that began our Universe.

COBE was launched Nov. 18, 1989, from Vandenberg Air Force Base, Calif., aboard a Goddard-managed Delta rocket. Goddard manages COBE for the Office of Space Science at NASA Headquarters in Washington, D.C.