Astronomy Picture Of the Day (APOD)Rectangular Ridges on Mars
What could cause rectangular ridges on Mars? As data flows in from the two spacecraft currently orbiting Mars, surface structures are seen that are not immediately understood. These structures pose puzzles that planetary geologists are eager to solve, as they might provide clues to past processes that have shaped Mars over billions of years.
D rad Bacteria: Candidate Astronauts
These bacteria could survive on another planet. In an Earth lab, Deinococcus radiodurans (D. rad) survive extreme levels of radiation, extreme temperatures, dehydration, and exposure to genotoxic chemicals. Amazingly, they even have the ability to repair their own DNA, usually with 48 hours. Known as an extremophile, bacteria such as D.
Venus: Just Passing By
Venus, the second closest planet to the Sun, is a popular way-point for spacecraft headed for the gas giant planets in the outer reaches of the solar system. Why visit Venus first? Using...
X Ray Rainbows
A drop of water or prism of glass can spread out visible sunlight into a rainbow of colors. In order of increasing energy, the well known spectrum of colors in a rainbow runs red, orange, yellow, green, blue, indigo, violet.
Accretion Disk Simulation
Don't be fooled by the familiar symmetry. The graceful spiral structure seen in this computer visualization does not portray winding spiral arms in a distant galaxy of stars. Instead, the graphic shows spiral...
Rocket Trail at Sunset
Bright light from a setting Sun and pale glow from a rising Moon both contribute to this stunning picture of a rocket exhaust trail twisting and drifting in the evening sky. Looking west...
Jupiter, Moons, and Bees
Rising before the Sun on September 4, Jupiter and an old cresent Moon gathered in the dim constellation of Cancer. Watching from a hillside near Austin, Texas, planet Earth, astrophotographer Russell Croman recorded this view of their passing as clouds gracefully dimmed the brilliant moonlight.
To Fly Free in Space
What would it be like to fly free over the seas and clouds of Earth? The first to experience such an "untethered space walk" were NASA astronauts Bruce McCandless and Robert Stewart during Space Shuttle mission 41-B in 1984.
The Milky Way Over Mount Blanc
Have you ever seen the band of our Milky Way Galaxy? Chances are you have never seen it like this -- nor could you. In a clear sky from a dark location at the right time, a faint band of light is visible across the sky. This band is the disk of our spiral galaxy.
Two Hours Before Neptune
Two hours before closest approach to Neptune in 1989, the Voyager 2 robot spacecraft snapped this picture. Clearly visible for the first time were long light-colored cirrus-type clouds floating high in Neptune's atmosphere. Shadows of these clouds can even be seen on lower cloud decks.