The most commonly accepted theory on the formation of the universe is what is known as "the Big Bang" theory. Many astronomers believe that the origins of the universe began with the concentration of gases and dust into matter of indeterminable density. About 13.7 billion years ago, that concentration of matter exploded in a "big bang" that spewed outward every known substance, all the minerals and gases that comprise the universe as we know it today. In the succeeding billions of years, the universe took shape as these substances formed stars, planets, asteroids, and what some believe is "dark matter."
The development of the Hubble Space Telescope, along with data gleaned from numerous probes launched into space by the U.S. National Aeronautics and Space Administration and its European and Russian counterparts, have enabled astronomers to peer farther into the distance than ever thought imaginable. In astronomical terms, the ability to peer far into space is the equivalent of peering into the universe's past. The Hubble telescope in particular has recorded and transmitted images that allow scientists to get closer to the origins of the universe than ever before. Images seen through the Hubble, as well as through other types of telescopes in locations like Hawaii, Chile, and Arizona, and through the use of radar, enable astronomers to measure distances to items many billions of light years (the distance light travels in a year) away and, consequently, to determine the age of those items.