Planets X ... in Outer Space

Article excerpt

After years of futile searching by astronomers around the world, a scientist at the Harvard-Smithsonian Center for Astrophysics in Washington says he has found the missing matter that would account for the 90 percent of the universe that has eluded detection by optical, radio and infrared telescopes.

Rudy Schild believes he has evidence that proves most of this mass consists of undetected planets - a vast number of them, more than anyone ever suspected. His announcement comes on the heels of the discovery of the first planet outside the Earth's solar system - verified by a Swiss team and then by an American one.

Schild achieved his breakthrough using a relatively new astrophysical-research technique called gravitational microlensing. The method allows scientists to detect the presence of planets by noting how their gravitational fields bend and amplify light from a distant source. His findings, accepted for publication in June in the prestigious Astrophysical Journal, touch on a number of important issues in astronomy, including the age of the universe.

Working nightly from 1992 through 1995 at the Mount Hopkins Observatory near Tucson, Ariz., Schild detected 50 planet-sized objects he calls "rogues" - Earth-sized celestial bodies drifting on the fringes of galaxies. Scientists had assumed all planets orbit stars, as does the Earth. Rogue planets, by contrast, are expelled from the orbits of young stars and wander aimlessly in isolation.

Astronomers calculate that there must be many more objects in the universe than so far detected to provide the gravitational forces that keep galaxies from spinning apart. Typically, these galaxies have vast, spiral-shaped geometries in which two curved arms rotate around an axis-like inner core - a shape similar to a pinwheel. Such galaxies, comprising billions of stars, are immense and create a massive centrifugal impetus that pushes outward from the central axis. Without huge masses to generate countervailing gravitational forces pulling inward, the majestic spiral arms of these galaxies would fly apart like a broken propeller. …