Tycho Brahe was the most meticulous astronomical observer of his time. Brahe, who lived between 1546 and 1601, set out to solve the day's most pressing astronomical problem: to determine whether the Earth or the Sun was at the center ...
Here lived one of the greatest thinkers in human history. Aristarchus lived on the Greek island of Samos, a small island in the center of the above picture that can be identified with a good map. Aristarchus, who lived from 310 BC ...
The planet Mercury resembles a moon. Mercury's old surface is heavily cratered like many moons. Mercury is larger than most moons but smaller than Jupiter's moon Ganymede and Saturn's moon Titan. Mercury is much denser ...
Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock. Mercury's diameter is about 4800 km, while the Moon's is slightly less at about 3500 km (compared with about 12,700 km for the Earth). But ...
Launched in the early 1970s Pioneer 10 and 11 were appropriately named - becoming the first spacecraft to travel through the asteroid belt, first to fly by Jupiter and Saturn, and the first human artifacts to venture beyond the solar system. Now ...
Launched in the summer of 1977, NASA's Voyager 1 and 2 spacecraft are now over 4.5 billion miles from the Sun. Still operational, the Voyagers are being tracked and commanded through the Deep Space Network. Having traveled beyond the outer ...
Researchers believe that the faint reddish smudge indicated by the arrow in the image above is a candidate for the most distant known galaxy which may have existed only a few hundred million years after the Big Bang. The image is part of the ...
NASA's robot spacecraft Galileo began its long voyage to Jupiter in October of 1989. In December of last year it arrived in the Jovian system, beginning its unprecedented, detailed exploration by dropping a probe into the gas giant's atmosphere. ...
French astronomer Charles Messier was born on June 26, 1730. Inspired by childhood sightings of comets and a solar eclipse visible from his home town of Badonvillier, he became an astronomer and comet hunter who kept careful records of his ...
Stars sometimes form in colorful ways. Pictured above is a small region in the nearby LMC galaxy where stars are forming. After a star is born, it may do several things to energize its immediate neighborhood. It may develop a strong wind which ...