Astronomy Picture Of the Day (APOD)A Colorful Aurora
A solar storm overtook the Earth on August 26th. The Earth survived unscathed, as usual, although many northerners reported an impressive display of aurora. Many of these auroras changed rapidly, with patterns appearing and disappearing sometimes in less than a second. Out away from city lights, observers also reported an unusually spectacular array of colors.
A3827: Cluster Cannibal
It was mealtime in galaxy cluster Abell 3827. The hungry cluster dominant galaxy in A3827's center is seen being fed. Breakfast included five smaller galaxies unfortunate enough to wander too close to the cluster's central supergiant galaxy. The remnants of these five galaxies can be seen in the center of this false-color picture.
The Sun Erupts
The Sun is a seething ball of extremely hot gas. Above, the Sun was captured by Skylab in 1973 throwing off one the largest eruptive prominences in recorded history. The Sun has survived for about 5 billion years, and will likely survive for another 5 billion.
Orion Star Colours
What determines a star's colour? Its temperature. Red stars are cool, around 3,000 kelvins (K), while blue stars are hotter and can have temperatures over 30,000 K. Our own lovely yellow Sun's temperature is a comforting 6,000 K.
Clouds of glowing hydrogen gas mingle with dark dust lanes in the Trifid Nebula, a star forming region in the constellation Sagittarius. In this and other similar emission nebulae, energetic ultraviolet light from an embedded hot young star strips electrons from the surrounding hydrogen atoms.
These are galaxies of the Hercules Cluster, an archipelago of "island universes" a mere 650 million light-years distant. This cluster is loaded with gas and dust rich, star forming, spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars.
The Magellanic Stream
Spanning the sky behind the majestic Clouds of Magellan is an unusual stream of gas: the Magellanic Stream. The origin of this gas might hold a clue to origin and fate of our Milky Way's most famous satellite galaxies: the LMC and the SMC.
Moon, Venus, Jupiter, Phoenix
Before a relaxing sunrise, the sky begins to glow with unusual delights. Such was the view from Papago Park in Phoenix, Arizona this April. The glittering objects visible in this photograph are, from lower left to upper right: Phoenix, our Moon, Venus, and Jupiter. Such proximity is somewhat unusual.
An Annular Eclipse of the Sun
An annular eclipse of the Sun was visible in parts of the Eastern Hemisphere on Saturday. The above picture was taken at that time by a video camera in Mersing on the East Coast of Malaysia and emailed to APOD yesterday from an internet cafe in Kuala Lumpur.
Vega is a bright blue star 25 light years away. Vega is the brightest star in the Summer Triangle, a group of stars easily visible summer evenings in the northern hemisphere. The name Vega...