The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

The safe arrival in the United States of 7,000 photo graphs of the planet Mars is an astronomical event of no small importance. To transport a delicate lens 18 inches in diameter from New ...

Some are almost spheres, like planets, but most are irregular shapes. Some are the size of small stones and pebbles. Some measure hundreds of kilometres across. The largest object is the asteroid ...

Astronomers have discovered an Earth-size planet that is showered with so much radiation, its atmosphere eroded away long ago ...

In 1992 astronomers reported the first planet-size masses around a dead star, the pulsar PSR1257+12, which sits 2,000 light-years away. Three years later came news of the first known exoplanet ...