Astronomy Picture of the Day

2004-09-14

A flying saucer from outer space crash-landed in the Utah desert last week after being tracked by radar and chased by helicopters. No space aliens were involved, however. The saucer, pictured above, was the Genesis sample return capsule, part ...

2004-09-13

What caused this ring of colors? At the time of this writing, MIT Physics Professor Walter Lewin had yet to find someone who can give the correct explanation. Not students. Not colleagues. Not APOD editors. He wonders how the astute readers ...

2004-09-12

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 Mercury is ...

2004-09-11 Dan Heller

The night had no moon, but the stars were out. And camped at 16,000 feet on Mt. Kilimanjaro, photographer Dan Heller recorded this marvelous 3 1/2 hour long exposure. Here the landscape is lit mostly by the stars. Flashlights give the tents an ...

2004-09-10

Staring across interstellar space, the alluring Cat's Eye nebula lies three thousand light-years from Earth. A classic planetary nebula, the Cat's Eye (NGC 6543) represents a final, brief yet glorious phase in the life of a sun-like star. This ...

2004-09-09 Robert Gendler

These three bright nebulae are often featured in telescopic tours of the constellation Sagittarius and the view toward the center of our Milky Way galaxy. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the nebula ...

2004-09-08

Why do some black hole surroundings appear brighter than others? In the centers of active galaxies, supermassive black holes at least thousands of times the mass of our Sun dominate. Many, called Seyfert Type I, are very bright in visible ...

2004-09-07

The closest and brightest supernova in over a decade was recorded just over a month ago in the outskirts of nearby galaxy NGC 2403. Officially tagged SN 2004dj, the Type IIP explosion likely annihilated most of a blue supergiant star as central ...

2004-09-06

A comet-like tail of glowing gas, 200,000 light-years long, streams from galaxy C153 as it plunges through galaxy cluster Abell 2125 at nearly 8 million kilometers per hour. Itself a member of the giant cluster of galaxies, C153 may once have ...

2004-09-05

The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60 thousand light years across, M51, also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky. The above image is ...