Astronomy Picture Of the Day (APOD)Star Trails in Northern Skies
As the Earth spins on its axis, the sky seems to rotate around us. This motion produces the beautiful concentric arcs traced out by the stars in this time exposure of the night sky.
Sailing upside down, 115 nautical miles above Earth, the crew of the Space Shuttle Endeavour made this spectacular time exposure of the southern aurora (aurora australis) in October of 1994. The aurora, also known...
Io: The Fissure King?
Is Io the solar system's Fissure King? Well, probably not ... but it is the most active volcanic moon. Active volcanoes on Jupiter's moon Io were a surprise discovery of the Voyager missions of the late 1970s.
Comet-like Clouds in the Cartwheel Galaxy
In a cartwheel-shaped galaxy far, far away, huge comet-shaped clouds of gas have been discovered racing through the nucleus at about 700,000 miles per hour. The aptly named Cartwheel Galaxy is actually about 500 million light years distant, its suggestive shape created by a head-on collision with a smaller galaxy.
Storm Clouds Over Jupiter
Storm clouds, similar to the familiar cumulonimbus thunderheads of Earth, appear to be present on Jupiter. The mosaic of images above shows the region near the raging edge of Jupiter's Great Red Spot, itself some 2 to 3 Earths wide, as observed by the Galileo spacecraft in June of this year.
The Radio Sky: Tuned to 408MHz
Tune your radio telescope to 408MHz (408 million cycles per second) and check out the Radio Sky! You should find that frequency on your dial somewhere between US broadcast television channels 13 and 14.
A Quasar Portrait Gallery
QUASARs (QUASi-stellAR objects) lie near the edge of the observable Universe. Discovered in 1963, astronomers were astounded - to be visible at such extreme distances of billions of light-years they must emit prodigious amounts of energy. Where does the energy come from?
Apollo 12 Visits Surveyor 3
Apollo 12 was the second mission to land humans on the Moon. The landing site was picked to be near the location of Surveyor 3, a robot spacecraft that had landed on the moon three years earlier. Pictured above, Apollo 12 astronauts Conrad and Bean retrieve parts from the Surveyor.
Gamma Ray Bursts from the Unknown
Gamma Ray Bursts (GRBs) pose one of the greatest mysteries of modern astronomy. About once a day, the gamma-ray sky lights up with a spectacular explosion. No one knows what causes these explosions or even how far away they are.
Fliers Around the Blue Snowball Nebula
Planetary nebulae are strange. First, they are gas clouds and have nothing to do with our Solar System's planets. Next, although hundreds of planetary nebulae have been catalogued and thousands surely exist in our Galaxy, aspects of the formation process are still debated.