THE recent discovery of planets apparently floating in space with no star to
orbit has baffled astronomers. Now a group of physicists in Australia has come
up with an extraordinary explanation: “They may not be isolated at all,” says
Robert Foot of the University of Melbourne. “They could be orbiting invisible
stars.”
The isolated planets were puzzling because, in the conventional picture,
planets form only in dense discs of gas and dust swirling around newborn stars.
But recent observations turned up objects that look very like our own Jupiter,
wandering in the Sigma Orionis star cluster
(Â鶹´«Ã½, 14 October,…
