Their tails point away from the sun

Usage examples of comets.

Because of their small mass, Tom explained, comets are readily affected by any outside gravitational tug.

Nemesis theorythat the death of the dinosaurs and the other periodic mass extinctions of the distant past were caused by a remote companion star to the Sun that regularly pelted the Earth with comets torn from the Oort Cloud.

You could scarcely toss it a few comets, for example, and coax it out of its orbit that way.

There were still plenty of stray comets at that distance, on the thin margins of the Oort Cloud.

Some day the bulk of the human race will live among the comets, not on planets and moons.

Nobody was likely to come visitingthe next nearest rogue comets would be on the order of tens of astronomical units awaybut if some prospector equipped with a blinker program did happen to come blundering by, all he would see would be a piece of property that some other developer had got to first.

There would be comets, toothousands of them swept out of the Oort Clouds of two systems as the black hole ploughed its way through to freedom.

There were even traces of amino acids, the complex organic compounds once delivered by long-vanished comets to rocky Earth, the compounds that had enabled life to emerge here: a wistful present from a visitor who had come too late.

Tory called up the register for regularly recurring comets and initiated a search.

There was no question that vast numbers of comets drifted through the interstellar void, unattached to any sun.

It was true that comets were periodically ejected from the solar system by the Sun, and sometimes even by Jupiter.

You understand, this comet would be less destructive if it were moving at the velocity comets usually move in the solar system, at thirty or forty kilometers per second.

When they started interviewing another astronomer about comets, he shut off the TV, made a rum and Coke, and walked out onto his front porch.

Though unspectacular, as comets go, it was nevertheless the first comet to appear since the birth of the telescope.

Discussions of the comets frequently occurred, during which I had occasion to voice some thoughts of mine which cast doubt upon the doctrines that have been previously held on this matter.