Astronomy Picture Of the Day (APOD)Aurora Through a Moonlit Sky
A night sky can glow in fascinating ways. Through a clearing in the woods, the pictured sky above Alaska shines by reflected light from a nearby city, by the brightness of the Moon, and by aurora.
The Rotten Egg Planetary Nebula
Not all evolving stars eject gas clouds that look like people. OH231.8+4.2 was a star much like our Sun that ran out of nuclear fuel to fuse in its core.
The Cat's Eye Nebula
Three thousand light-years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals The Cat's Eye Nebula to be one of the most complex planetary nebulae known.
Mars Rocks, Sojourner Rolls
This sharp color image featuring Mars rock Yogi and the rolling Sojourner robot shows off Yogi's two-toned surface. Yogi appears to be leaning into the prevailing winds causing some to suggest that its color contrast may be caused by the accumulation of rust colored dust on its windward face.
The USNO Millennium Time Ball
In the nineteenth century, dropping a time ball from a prominent location was a practical way of communicating the time to the surrounding country side and ships at sea. Initiating a fledgling time service for the United States, the U.S. Naval Observatory dropped a time ball at precisely noon every day begining in 1845.
X Ray Jet From Centaurus A
Spanning over 25,000 light-years, comparable to the distance from the Sun to the center of our own Milky Way galaxy, a cosmic jet seen in X-rays blasts from the center of Centaurus A. Only 10 million light-years away, Centaurus A is a giant elliptical galaxy - the closest active galaxy to Earth.
In the Heart of the Tarantula Nebula
In the heart of monstrous Tarantula Nebula lies one of the most unusual star clusters. Known as NGC 2070 or R136, it is home to a great number of hot young stars. The energetic light from these stars continually ionizes nebula gas, while their energetic particle wind blows bubbles and defines intricate filaments.
30 Doradus: The Tarantula Nebula
30 Doradus is an immense star forming region in a nearby galaxy known as the Large Magellanic Cloud. Its spidery appearance is responsible for its popular name, the Tarantula Nebula, except that this tarantula is about 1,000 light-years across, and 165,000 light-years away in the southern constellation Dorado.
Neptune in Infrared
Neptune has never looked so clear in infrared light. Neptune is the eighth most distant planet from the Sun, thirty times the Earth-Sun distance. Neptune is the fourth largest planet, almost four times Earth's diameter. Surprisingly, Neptune radiates about twice as much energy as it receives from the Sun.
The Magnetic Carpet Of The Sun
The Sun has a magnetic carpet. Its visible surface appears to be carpeted with tens of thousands of magnetic north and south poles joined by looping field lines which extend outward into the Solar Corona.