Fuller whispered to Morey out of the corner of his sagging mouth. "What on Earth--I mean, what in Space is that thing? We're within only a few hundred miles, you said, so it must be pretty small. How could it pull us around like this?" "It's a dead white dwarf--a 'black dwarf', you might say," Morey replied. "As the density of such matter increases, the volume of the star depends less and less on its temperature. In a dwarf with the mass of the sun, the temperature effect is negligible; it's the action of the forces within the electron-nucleon gas which makes up the star that reigns supreme. "It's been shown that if a white dwarf--or a black one--is increased in mass, it begins to decrease sharply in volume after a certain point is reached. In fact, no _cold_ star can exist with a volume greater than about one and a half times the mass of the sun--as the mass increases and the pressure goes up, the star shrinks in volume because of the degenerate matter in it. At a little better than 1.4 times the mass of the sun--our sun, I mean: Old Sol--the star would theoretically collapse to a point. "That has almost happened in this case. The actual limit is when the star has reached the density of a neutron, and this star hasn't collapsed that far by a long shot. "But that star is only forty kilometers--_or less than twenty-five miles_ in diameter!" It took nearly two hours of careful juggling to get an orbit which Arcot considered reasonably circular. And when they finally did, Wade looked at the sky above them and shouted: "Say, look! What are all those streaks?" Arcing up from the surface of the dull red plain below them and going over the ship, were several dim streaks of light across the sky. One of them was brighter than the rest, a bright white streak. The streaks didn't move; they seemed to have been painted on the sky overhead, glowing bands of unwavering light. "Those," said Arcot, "are the nebulae. That wide streak is the one we just left. The bright streak must be a nearby star. "They look like streaks because we're moving so fast in so small an orbit." He pointed to the red star beneath them. "We're less than twenty miles from the center of that thing! We're almost exactly thirty kilometers from its center, or about ten kilometers from its surface! But, because of it's great mass, our orbital velocity is something terrific! "We're going around that thing better than three hundred times every second; our 'year' is three milliseconds long! Our orbital velocity is _seven hundred thousand kilometers per second_! "We're moving along at about a fifth of the speed of light!" "Are we safe in this orbit?" Fuller asked. "Safe enough," said Arcot bitterly. "So damned safe that I don't see how we'll ever break free. We can't pull away with all the power on this ship. We're trapped! "Well, I'm worn out from working under all that gravity; let's eat and get some sleep."