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Floating freely in space, unattached to stars, rogue planets might populate most galaxies by the quadrillions.
Even science has its folklore and myths - among them rogue" planets. For years a few astronomers theorized that these objects -- about the size of Earth or Uranus -- wandered freely on the peripheries of galaxies and interstellar space unfettered by the gravitational leash of shepherding stars. Undetectable and unobservable, rogue planets existed in a nebulous theoretical limbo.
Little by little they slipped unconsciously into the lexicon of astro-talk. "The phrase came into use about 30 years ago," explains physicist Freeman Dyson from his office at the Institute for Advanced Studies in Princeton, New Jersey. "I'm not sure who first started talking about them. The idea was just something in the air. As far as I know, there is no evidence that so-called rogue planets exist."
Until now.
In June 1996, Rudy Schild of the HarvardSmithsonian Center for Astrophysics in Cambridge, Massachusetts, published observational data accumulated over 10 years that seemed to show that rogue planets could not only be demonstrably real, but could be ubiquitous, even essential species on the taxonomic tree of astronomical objects. Schild's gone even further: He thinks rogue planets are virtually a cosmic Rosetta stone, the key to understanding some of the most vexing enigmas in astrophysics.
Schild reported in the June 10, 1996 Astrophysical Journal that he and his collaborator, statistician David Thomson of Lucent Technologies, found the gravitational signature of at least 50 Earth- to Uranus-mass objects maundering on the fringes of an elliptical galaxy one to two billion light-years away. This galaxy is catalogued simply as Gl.
By any measure, this could be a big discovery - a big discovery few astronomers are buying. Critics concede, however, that the observations themselves are unimpeachable. In fact, multiple observatories all detect the same phenomena Schild reports seeing on his own 1.2-meter telescope at the Mt. Hopkins Observatory in Arizona. When you get right down to it, this rogue planet dispute is not over facts, but interpretation.
Seeing Double
Frozen and lifeless, hundreds of degrees below zero, too far from starlight to be seen, rogue planets can only be identified indirectly by their tell-tale gravitational tracks. They can be found using a technique...