Astronomy Picture Of the Day (APOD)Unexpected X-rays from Comet Hyakutake
The first X-rays ever detected from a comet were discovered from Comet Hyakutake with the ROSAT satellite on March 27th. The discovery is particularly surprising because there was little previous indication that comets emit any significant X-radiation.
Comet Hyakutake and a Tree
Comet Hyakutake is still visible as it continues its orbit around the Sun. The comet will brighten again in late April and early May. The above fascinating picture was taken with a three minute exposure. In the middle of the exposure, the photographer cleverly set off a flash, momentarily illuminating the foreground tree.
A Spiral Galaxy Gallery
A progression of beautiful spiral galaxies is illustrated above with three photographs from NASA's Ultraviolet Imaging Telescope (UIT). Flying above the Earth's obscuring layer of atmosphere on the Space Shuttle Columbia during...
Uranus's Moon Oberon: Impact World
Oberon is the most distant and second largest moon of Uranus. Discovered by William Herschel in 1787, the properties of the world remained relatively unknown until the robot spacecraft Voyager 2 passed it during its flyby of Uranus in January 1986.
Uranus's Moon Umbriel: A Mysterious Dark World
Why is Umbriel so dark? This dark moon reflects only half the light of other Uranus' moons such as Ariel. And what is that bright ring at the top? Unfortunately, nobody yet knows. These questions presented themselves when Voyager 2 passed this satellite of Uranus in January 1986.
Andromeda Nebula: Var!
In the 1920s, using photographic plates made with the Mt. Wilson Observatory's 100 inch telescope, Edwin Hubble determined the distance to the Andromeda Nebula - decisively demonstrating the existence of other galaxies far beyond the Milky Way.
The Perseus Cluster of Galaxies
Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies.
The Keyhole Nebula Near Eta Carinae
The dark dusty Keyhole Nebula gets its name from its unusual shape. Designated NGC 3324, the Keyhole Nebula is a smaller region superposed on the bright Eta Carina Nebula. The Eta Carina Nebula...
A Lucky Lunar Eclipse
Tonight's full moon would normally washout the spectacle of Comet Hyakutake's lovely tail, even for those far from light polluted skies. Except that tonight comet observers are in luck - the dance of the planets calls for a total lunar eclipse! Lunar eclipses are caused when the Moon passes through the Earth's shadow.
Atlantis Approaches Mir
Imagine flying though space and approaching the Mir space station. The crew of the Space Shuttle Atlantis did just this in a mission that ended only two days ago. Mir, now 10 years old, is equipped for scientific experiments in astronomy, physics, materials, biology and chemistry.