Astronomy Picture Of the Day (APOD)Saturn with Moons Tethys and Dione
Saturn and two of its larger moons - Tethys and Dione - were photographed by the Voyager 1 spacecraft which flew by the planet in November of 1980. This picture gives an indication of Saturn's extensive ring system, which can be seen casting a shadow on the planet, as does Tethys.
Saturn's Cloud Tops
This close-up of the tops of Saturn's clouds was taken by the Voyager 1 robot spacecraft as it passed the giant planet in November 1980. Saturn's clouds are mostly composed of hydrogen and helium gas, but the small addition of other elements gives the clouds their colors.
Spiral Galaxy M90
Spiral galaxy M90 is near the center of the Virgo Cluster of Galaxies - the closest cluster of galaxies to the our own Milky Way Galaxy. Also dubbed NGC 4569, this galaxy has a very compact and bright nucleus.
The McMath-Pierce Solar Observatory
This odd-looking structure silhouetted in the foreground houses the three largest solar telescopes in the world. Located in Kitt Peak, Arizona, the largest telescope inside the McMath-Pierce Facility is 1.6-meters in diameter and contains only mirrors. The telescope contains no windows or lenses because focusing bright sunlight would overheat them.
Comet Hyakutake's Orbit
Where did Comet Hyakutake come from? The orbits of the Earth and this brightening comet are shown in the above diagram. The blue disk is bounded by the circular orbit of the Earth about the central Sun. The comet's path outlines the green shape.
Here Comes Comet Hyakutake
The reaction of ancient peoples to the appearance of bright comets has toppled empires, de-throned kings, and been taken as a sign of great things to come. Probably some of these comets did not get as bright as Comet Hyakutake ("hyah-koo-tah-kay") will in the next two weeks.
The Colorful Clouds of Rho Ophiuchi
The many spectacular colors of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light.
Hubble Telescope Maps Pluto
No spacecraft from Earth has yet explored Pluto but astronomers have found ways of mapping its surface. A stunning map of this distant, diminutive planet, the first based on direct images, was revealed late last week in a Hubble Space Telescope press release.
Mir is 10
The first module of the Russian Space Agency's Mir Space Station was launched into orbit 10 years ago (on February 20, 1986). Mir has since been substantially expanded in orbit by adding additional modules including the Kvant Astrophysics Module (1987) and recently a docking module.
Arecibo: The Largest Telescope
The Arecibo radio telescope is currently the largest single-dish telescope in the world. First opening in 1963, this 305 meter (1000 foot) radio telescope resides in a natural valley of Puerto Rico. The Arecibo...