Astronomy Picture Of the Day (APOD)THEMIS of Mars
Not an ancient Greek goddess, THEMIS is modern acronese for THermal EMission Imaging System. Above is this remarkable instrument's premier infrared image of Mars, from the newly orbiting Mars Odyssey spacecraft. Taken...
M87 s Energetic Jet
An energetic jet from the core of giant elliptical galaxy M87 stretches outward for 5,000 light-years. This monstrous jet appears in the panels above to be a knotted and irregular structure, dectected across the spectrum, from x-ray to optical to radio wavelengths.
Halloween and the Ghost Head Nebula
Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With our modern calendar, however, the real cross-quarter day will occur next week.
Anticrepuscular Rays Over Colorado
What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds.
Spinning Black Holes and MCG 6 30 15
What makes the core of galaxy MCG-6-30-15 so bright? Some astronomers believe the answer is a massive spinning black hole. If so, this would be the first observational indication that it is possible to make a black hole act like a battery -- and tap into its rotational energy.
NGC 2346: A Butterfly-Shaped Planetary Nebula
It may look like a butterfly, but it's bigger than our Solar System. NGC 2346 is a planetary nebula made of gas and dust that has evolved into a familiar shape. At the heart of the bipolar planetary nebula is a pair of close stars orbiting each other once every sixteen days.
Sher 25: A Pending Supernova
No supernova has ever been predicted. These dramatic stellar explosions that destroy stars and disperse elements that compose people and planets are not so well understood that astronomers can accurately predict when a star will explode - yet. Perhaps Sher 25 will be the first.
Elements in the Aftermath
Massive stars spend their brief lives furiously burning nuclear fuel. Through fusion at extreme temperatures and densities surrounding the stellar core, nuclei of light elements like Hydrogen and Helium are combined to heavier elements like Carbon, Oxygen, etc. in a progression which ends with Iron.
Odyssey at Mars
After an interplanetary journey lasting 200 days, the Mars Odyssey spacecraft has entered orbit around the Red Planet. This latest success is welcome as in the past, Mars has often seemed a difficult planet to visit.
The Matter of Galaxy Clusters
Situated over 2,000,000,000 (two billion) light-years from Earth, galaxies in cluster Abell 2390 (top) and MS2137.3-2353 (bottom) are seen in the right hand panels above, false-color images from the Hubble Space Telescope. Corresponding panels on the left reveal each cluster's x-ray appearance in images from the Chandra X-ray Observatory.