Astronomy Picture Of the Day (APOD)Europa: Ancient Water World
Beneath the cold icy surface of Jupiter's moon Europa are probably the only oceans of water in our Solar System outside of Earth. These oceans, possibly 50 kilometers deep, might also be the most likely local place to find extra-terrestrial life.
Ganymede: Moonquake World
Ganymede probably undergoes frequent ground shaking events not unlike terrestrial earthquakes. Ganymede, the largest moon of Jupiter and the Solar System, has a thick outer coating of water ice. Passing Voyager spacecraft found...
Earth's Moon, A Familiar Face
The above mosaic of the Earth's Moon was compiled from photos taken by the spacecraft Clementine in 1994. This image represents the side of the Moon familiar to Earth dwellers. The Moon revolves around the Earth about once every 28 days.
Hot Gas and Dark Matter
Is the gravity of the above galaxies high enough to contain the glowing hot gas? Superposed on an optical picture of a group of galaxies is an image taken in X-ray light. The X-ray...
Subrahmanyan Chandrasekhar 1910-1995
On August 21, 1995 one of the greatest astrophysicists of modern times passed away. Subrahmanyan Chandrasekhar was a creative, prolific genius whose ability to combine mathematical precision with physical insight changed humanity's view of stellar physics.
X-Raying the Moon
Above is a picture of the Moon taken in X-rays by the Roentgen Observatory Satellite ROSAT in 1990. This famous picture shows three distinct regions: a bright X-ray sky, a bright part of the Moon, and a relatively dark part of the Moon.
Skylab Over Earth
Skylab was an orbiting laboratory launched by a Saturn V rocket in May 1973. Skylab was visited three times by NASA astronauts who sometimes stayed as long as two and a half months. Many scientific tests were preformed on Skylab, including astronomical observations in ultraviolet and X-ray light.
Saturn V: NASA's Largest Rocket
Pictured, a NASA Saturn V rocket blasts off on July 16th, 1969 carrying the crew of Apollo 11 to the Moon. The Saturn V rocket was the largest rocket ever used by NASA, and the only one able to lift the large masses needed to land astronauts on the moon and returning them safely.
Dusty Galaxy Centaurus A
One of the most unusual galaxies known, Centaurus A, is pictured above. Cen A is marked by dramatic dust lanes that run across the galaxy's center. These dust lanes are so thick they almost completely obscure the galaxy's center in visible light.
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.