Astronomy Picture Of the Day (APOD)EUVE Sky Map
The stars beyond the Sun and the distant galaxies should be undetectable at extreme ultraviolet wavelengths. At least that was the conventional wisdom when it was first realized that the space between the stars is filled with hydrogen, a strong absorber of extreme ultraviolet light.
Moonrise Over Seattle
Is the Moon larger when near the horizon? No -- as shown above, the Moon appears to be very nearly the same size no matter its location on the sky. Oddly, the cause or causes for the common Moon Illusion are still being debated.
The Southern Sky in Warm Hydrogen
A robotic telescope with red sunglasses in Chile has been photographing the entire southern sky for years. The result, shown above, is the most complete sky map of the most common visible light emitted from the most abundant element in our Galaxy: hydrogen. A very specific red color emitted by warm ionized hydrogen was observed.
An Apollo 17 Panorama
What would it be like to stand on the surface of another world, to look all around you, and to try to figure out how this world got there? To get an idea, scroll right. In 1972 during the Apollo 17 mission, astronauts Harrison Schmitt and Eugene Cernan found out first hand.
During 1968, the Apollo 8 crew flew from the Earth to the Moon and back. The crew, consisting of Frank Borman, James Lovell, and Willian Anders, were launched atop a Saturn V rocket on December 21, circled the Moon ten times in their command module, and landed back on Earth on December 27.
Shuttle Engine Blast
The Space Shuttle Discovery's orbital maneuvering system (OMS) engine firing produced this dramatic flare as it cruised "upside down" in low Earth orbit. Discovery was named for a ship commanded by Captain James Cook RN, the 18th Century English astronomer and navigator.
The Spiral Arms of NGC 4622
While stirring a morning cup of coffee and thinking cosmic thoughts many astronomers would glance at this Hubble Space Telescope image of spiral galaxy NGC 4622 and assume that the galaxy was rotating counterclockwise in the picture.
A small inner moon of Saturn, Enceladus is only about 500 kilometers in diameter. But the cold, distant world does reflect over 90 percent of the sunlight it receives, giving its surface about the same reflectivity as new-fallen snow.
Local Group Galaxy NGC 6822
Nearby galaxy NGC 6822 is irregular in several ways. First, the galaxy's star distribution merits a formal classification of dwarf irregular, and from our vantage-point the small galaxy appears nearly rectangular. What strikes...
Quantum Gravity Claimed Detected on Earth
Does gravity come in chucks? A theory known as Quantum Mechanics tells us about how the universe works on the smallest scales, while Einstein's General Theory of Relativity tells us about how gravity and the universe works on the largest scales. So far, no complete theory has been able to encompass them both.