Astronomy Picture Of the Day (APOD)X-Rays From The Galactic Center
Exploring quasars and active galaxies in the distant universe, astronomers have come to believe that most galaxies have massive black holes at their centers. Swirling stars and a strong, variable radio source offer convincing evidence that even our own Milky Way galaxy's center harbors such a bizarre object, a mere 30,000 light-years away.
A Big Black Hole Floats By
A black hole glides silently through space. Is there any way to know it's there? Until last week, all objects that might be black holes in our Galaxy were part of binary star systems.
NGC 7635: The Bubble Nebula
What created this huge space bubble? A massive star that is not only bright and blue, but also emitting a fast stellar wind of ionized gas. The Bubble Nebula is actually the smallest...
V4641 Sgr: The Closest Black Hole Candidate
An object many astronomers believe is a black hole has been found only 1500 light-years from Earth, making it the closest black hole candidate. Although dramatic explosions emanate from the object, it is far enough away so that we are in no danger.
The Compton Gamma Ray Observatory
The Compton Gamma Ray Observatory (CGRO) was the most massive instrument ever launched by a NASA Space Shuttle in 1991 and continues to revolutionize gamma-ray astronomy. Before Compton loses more stabilizing gyroscopes, NASA is considering firing onboard rockets to bring it on a controlled reentry into the ocean.
The Sun Also Rises
Sunrise seen from low Earth orbit can be very dramatic indeed (and the authors don't apologize to Hemingway for using his title!). In this breathtaking view from the space shuttle Endeavor, the Sun is just visible peaking over towering anvil-shaped storm clouds.
Chandra Resolves the Hard X Ray Background
It is everywhere but nobody knew why. In every direction at all times, the sky glows in X-rays. The X-ray background phenomenon was discovered over 35 years ago, soon after the first X-ray satellites were launched, and has since gone unexplained.
A Skygazers Full Moon
This dramatically sharp picture of the full moon was recorded on 22 December, 1999 by astroimager Rob Gendler. Big, beautiful, bright, and evocative, it was the last full moon of the Y1.9Ks, pleasing and inspiring even casual skygazers.
NGC 6791: An Old, Large Open Cluster
NGC 6791 is one of the oldest and largest open clusters of stars known. But how did it get so dirty? Open star clusters usually contain a few hundred stars each less than a billion years old.
The Rosette Nebula in Hydrogen, Oxygen, and Sulfur
The Rosette Nebula is a large emission nebula located 3000 light-years away. The great abundance of hydrogen gas gives NGC 2237 its red color in most photographs. The wind from the open cluster of stars known as NGC 2244 has cleared a hole in the nebula's center.