the stars and galaxies we know today. Dark-MatterThe destiny of our expanding universe depends on how much matter it contains and whether that will be enough to one day stop the expansion from the Big Bang. When astronomers actually count up all the visible matter—the stuff that gives off light—the answer is clearly no (or so they say), but scientists have apparently learned over the past several decades that the answer isn’t so cut-and-dried. Observations reveal that vast halos of invisible matter surround galaxies and galaxy clusters. This dark matter adds up to about ten times more mass than the visible stars, gas, and dust seen in galaxies. And there may be more. The “inflationary theory”, if true, demands that this dark stuff makes up between 90 and 99 percent of the universe. Astronomers have yet to determine what constitutes this dark matter, although some leading candidates go by the names MACHOs, WIMPs, and neutrinos.MACHOsShort for MAssive Compact Halo Objects, MACHOs could exist in huge numbers in vast halos surrounding galaxies. In the past few years, astronomers have actually detected several examples of MACHO-like objects in our galaxy, though not yet enough to account for all the dark matter known to reside there. Brown dwarfs, with a size between normal stars and planets, could be one type of MACHO. These objects form like stars but don't have enough mass to begin the nuclear fusion reactions that cause stars to shine brightly. Other could be MACHOs include planets, about a dozen of which have been discovered outside our own solar system in the past couple of years, and the halo objects that have recently been detected as they magnify and distort the light from stars in nearby galaxies, which, by the way, is how they find out these “dark -matters” exist. They see the light from other planets distorted by something invisible, thus finding this “dark-matter”.WIMPsSho...
