Astronomy Picture Of the Day (APOD)Recycling Cassiopeia A
For billions of years, massive stars in our Milky Way Galaxy have lived spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After a few million years, the enriched material is blasted back into interstellar space where star formation begins anew.
M51: X Rays from the Whirlpool
Fresh from yesterday's episode, a popular pair of interacting galaxies known as the Whirlpool debut here beyond the realm of visible light -- imaged at high energies by the orbiting Chandra X-ray Observatory. Still turning in a remarkable performance, over 80 glitering x-ray stars are present in the Chandra image data from the region.
M51: Cosmic Whirlpool
Follow the handle of the Big Dipper away from the dipper's bowl, until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you'll likely find this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog.
If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the shape traced out by the Sun over the course of a year is called an analemma.
Weighing Empty Space
Sometimes staring into empty space is useful. Pictured above is a region of sky that was picked because it had, well, nothing: no bright stars, no bright galaxies, and no picturesque nebulas. What could not be avoided, however, were a few stars in our own Galaxy, and many distant galaxies strewn across the universe.
The Galactic Center Across the Infrared
The center of our Galaxy is obscured in visible light by dark dust that rotates with the stars in the Galactic Plane. In this century, however, sensors have been developed that can detect light more red that humans can see - light called infrared.
Io: Moon Over Jupiter
Whimsical and creative, this multiple exposure suggests that planet Earth's sky could be very dramatic indeed if it were graced by many moons. And in James Thurber's well-known children's story, Princess...
Young Star Clusters in an Old Galaxy
Elliptical galaxy NGC 4365 is old, probably about 12 billion years old. Like most elliptical galaxies, this galaxy was thought to be full of old stars too, its burst of star forming activity having long since ended.
Interstellar Dust Bunnies of NGC 891
What is going on in NGC 891? This galaxy appeared previously to be very similar to our own Milky Way Galaxy: a spiral galaxy seen nearly edge-on. However, recent high-resolution images of NGC 891's dust show unusual filamentary patterns extending well away from its Galactic disk.