Astronomy Picture Of the Day (APOD)Uranus' Moon Ariel: Valley World
What formed Ariel's valleys? This question presented itself when Voyager 2 passed this satellite of Uranus in January 1986. Speculation includes that heating caused by the ancient tides of Uranus caused moonquakes and massive shifting of the moon's surface.
Von Braun's Wheel
Orbiting 1,075 miles above the Earth, a 250 foot wide, inflated, reinforced nylon "wheel" was conceived in the early 1950s to function as a navigational aid, meteorological station, military platform, and way station for space exploration by rocket pioneer Wernher von Braun.
A Mysterious Cone Nebula
Sometimes the simplest shapes are the hardest to explain. For example, the origin of the mysterious cone-shaped region located just below the center of the above picture remains a mystery. The dark region clearly contains much dust which blocks light from the emission nebula and open cluster NGC 2264 behind it.
Julius Caesar and Leap Days
Today, February 29th, is a leap day - a relatively rare occurrence. Advised by Alexandrian astronomer Sosigenes, Roman dictator Julius Caesar, pictured above in a self-decreed minted coin, created a calender system in 46 BC that contained one leap day every four years.
Explosions Discovered Near Galactic Center
Tremendous explosions near the center of our Galaxy were discovered just this past December and are being announced today by a paper in Nature and a press conference at NASA. Bursts like these have...
X-ray Moon and X-ray Star
An X-ray star winks out behind the Moon in these before and after views of a lunar occultation of the galactic X-ray source designated GX5-1. The false color images were made using data...
On rare but spectacular occasions, fireballs, meteors brighter than the brightest stars, flash through the heavens - sometimes making audible sounds and occasionally surviving to strike the Earth's surface. The path of one such...
A High Energy Fleet
Looking like a fleet of futuristic starcruisers poised over planet Earth, NASA's highly successful series of High Energy Astrophysical Observatory (HEAO) spacecraft appear above in a vintage illustration. Labeled A, B, and C in this conceptual picture, the spacebased telescopes were known as HEAO-1, HEAO-2, and HEAO-3 respectively.
Tanks for the Lift
Sixteen minutes after the liftoff of STS-29, the Space Shuttle Discovery's jettisoned External Tank (ET) is seen here, in a photograph by shuttle astronaut James P. Bagian, falling back towards Earth. The 154 foot long ET is the largest non-reusable component in the Shuttle system.
Apollo 15: Driving on the Moon
Apollo 15 astronaut James Irwin works on the first Lunar Roving Vehicle, before he and fellow astronaut David Scott take it out for a drive. Sloping up behind the lunar module "Falcon" on the left are lunar mountains Hadley Delta and Apennine Front, while about 5 kilometers behind Irwin is St. George Crater.