Little Inhabited Stars

When astronomers (or science-fiction writers) speculate about nonearthly kinds of life, they generally think of strange beings existing on planets revolving around a star that is at the proper distance to keep them reasonably warm. Astronomer Harlow Shapley, former head of the Harvard Observatory, has figured that there are probably 100,000 life-bearing planets in the Milky Way galaxy. Last week Shapley suggested that the universe may contain another class of celestial bodies that could sustain life. They are neither planets nor true stars, and are somewhere in between the two in size--perhaps 100 times bigger than the planet Jupiter or 1/100th the size of the sun.

These "Lilliputian stars" do not glow like regular stars; the pressure and temperature inside them are not high enough to support the thermonuclear reactions that keep stars hot. But they need not be cold. "The heat to support life," said Shapley, "would come from their interiors, and they would not be dependent on a sun as we are. In such bodies, radioactive thorium or potassium might provide a source of energy."

The kind of life that might develop on the surface of a small, central-heated star would not resemble earthly life. It would have to get along without light, except perhaps faint starlight, and it would have to cope with gravitation and probably atmospheric pressures enormously greater than are felt on earth. But there is no reason why life in such a place could not evolve into intelligent forms.

Dr. Shapley does not know how many such bodies exist in the Milky Way galaxy. They cannot be seen with the biggest telescopes because they give off no visible light, only a little infrared. But he suspects they may be even more numerous than visible stars.

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