Astronomy Picture Of the Day (APOD)18 Miles From Deimos
Diminutive Deimos is the smallest of the two tiny Moons of Mars. Potato shaped and barely 6 miles wide this asteroid-like body was visited by the Viking 2 orbiter in 1977. This image was made when the spacecraft approached to within 18 miles of Deimos' surface.
Sun and Winter Solstice 1996
Today is the Winter Solstice for 1996. After steadily sinking in Northern Hemisphere skies, the Sun is now at its lowest declination - marking the first day of Northern Winter (but Southern Summer!). The Earth...
The UV SMC from UIT
Translated from the "acronese" the title reads - The UltraViolet Small Magellanic Cloud from the Ultraviolet Imaging Telescope. FYI, the four ultraviolet images used in this mosaic of the nearby irregular galaxy known...
Comet Hale-Bopp Inbound
Headed toward the inner Solar System, the much anticipated Comet Hale-Bopp has promised to put on a big show next spring. The comet's apparent brightness is currently approaching 4th magnitude and its inbound journey has been closely followed by many observers.
A Sky Full Of Hydrogen
Interstellar space is filled with extremely tenuous clouds of gas which are mostly Hydrogen. The neutral hydrogen atom (HI in astronomer's shorthand) consists of 1 proton and 1 electron. The proton and electron spin like tops but can have only two orientations; spin axes parallel or anti-parallel.
Mercury, the closest planet to the Sun, remains the most mysterious of the Solar System's inner planets. Hiding in the Sun's glare it is a difficult target for Earth bound observers.
Nebula Nova Cygni Turns On
Old photographs show no evidence of the above nebula. In 1992, a white dwarf star in Cygnus blew off its outer layers in a classical nova explosion: an event called Nova Cygni 1992. Light flooded the local interstellar neighborhood, illuminated this existing gas cloud, excited the existing hydrogen, and hence caused the red emission.
Microlensing of the Einstein Cross
The famous "Einstein Cross" is a case where a single object is seen four times. Here a very distant QSO happened to be placed right behind a massive galaxy. The gravitational effect...
Our Solar System from Voyager
After taking spectacular pictures of our Solar System's outer planets, Voyager 1 looked back at six planets to take our Solar System's first family portrait. Here Venus, Earth, Jupiter, Saturn, Uranus, and Neptune, were all visible across the sky.
Disorder in Stephan's Quintet
Five closely grouped galaxies are visible in this image made using the Kitt Peak National Observatory 2.1 meter telescope. The grouping is commonly known as Stephan's Quintet. Four of the galaxies show essentially the same redshift suggesting that they are at the same distance from us.