Astronomy Picture Of the Day (APOD)M3: Inconstant Star Cluster
Star clusters appear constant because photographs of them are frozen in time. In reality, though, cluster stars swarm the center and frequently fluctuate in brightness. Although the time it takes for stars to cross...
Mosaic of Endurance Crater on Mars
Where should this Martian rover explore next? Possible choices for the Opportunity rover team on Earth in early August were to send the Martian robot inside Endurance crater toward the arc-shaped sand dunes...
Sunspot Loops in Ultraviolet
It was a quiet day on the Sun. The above image shows, however, that even during off days the Sun's surface is a busy place. Shown in ultraviolet light, the relatively cool dark regions have temperatures of thousands of degrees Celsius.
The Averted Side Of The Moon
This vintage 60-kopek stamp celebrates a dramatic achievement. On the 7th of October, 1959 (7/X/1959), the Soviet interplanetary station which has come to be called "Luna 3" successfully photographed the far side of the moon giving denizens of planet Earth their first ever view of this hidden hemisphere.
Kepler s SNR from Chandra, Hubble, Spitzer
Light from the stellar explosion that created this energized cosmic cloud was first seen on planet Earth in October 1604, a mere four hundred years ago. The supernova produced a bright new star in early 17th century skies within the constellation Ophiucus.
Moonsets are not often quite as exciting as this one. But amateur astronomer Marc-Andre Besel was impressed by the brilliant lighting displays that joined the first quarter Moon and stars of the constellation Scorpius in western skies.
N11: A Giant Ring of Emission Nebulas
How did this unusually large nebula form? One of the largest nebulas yet detected is actually a complex ring of emission nebulas connected by glowing filaments. The unusual network, known as N11, spans over...
SpaceShipOne Wins the X Prize
Human space flight has entered the domain of private companies. Previously, large countries like the US and Russia have hired privately owned civilian companies to do specific tasks in support of their public human space flight programs.
NGC 6823: Cloud Sculpting Star Cluster
Star cluster NGC 6823 is ready for its close-up. The center of the open cluster, visible on the upper right, formed only about two million years ago and is dominated in brightness by a host of bright young blue stars.
Comet Hale Bopp and the North America Nebula
Comet Hale-Bopp's 1997 encounter with the inner Solar System allowed many breath-taking pictures. Above, Comet Hale-Bopp was photographed crossing the constellation of Cygnus, sporting spectacular yellow dust and blue ion tails. Visible on the right in red is the North America Nebula, a bright emission nebula observable from a dark location with binoculars.