... Jupiter's Rings . ... Unlike Saturn's bright rings which are composed of chunks of rock and ice, Jupiter's rings appear to consist of fine particles of dust. ... Exploring Saturn's Rings . ... By watching a star flicker and fade as it passed behind Saturn's rings, NASA's Voyager 2 spacecraft was able explore the ring system in amazing detail. ... Saturn's spectacular system of bright rings has been the subject of study and wonder since Galileo first turned his telescope on the ringed planet in 1610....

... 2004 September 18 . M55: Globular Star Cluster . ... Explanation: The fifty-fifth entry in Charles Messier's catalog, M55 is a large and lovely globular cluster of around 100,000 stars. ... Globular star clusters like M55 roam the halo of our Milky Way Galaxy as gravitationally bound populations of stars known to be much older than stellar groups found in the galactic disk. Astronomers who make detailed studies of globular cluster stars can accurately measure the cluster ages and distances. ...

... Tonight's Sky . ... SUN MOON MERCURY VENUS MARS, JUPITER SATURN . ... Observing . ... Why do the constellations and the Moon appear upside down from the Southern Hemisphere? ... From the Southern Hemisphere, any object or constellation that lies near the celestial equator (the imaginary line that divides the northern and southern halves of the sky) would appear both upside down and reversed left to right compared to a northern perspective. ... Get instant access to subscriber content on Astronomy...

... Bad Astronomy . ... Bitesize Astronomy . ... Last week's Snack talked about how black holes can affect the environment around them in such a way as to be very bright . ... It's a common misconception that black holes always have matter swirling into them. ... As this matter gets closer and closer to the black hole it piles up and a large, fairly flat disk forms. This is called the accretion disk , because matter from this disk accretes (that is, falls in) on the black hole. ... 2008 Phil Plait. ...

... Kalirai and Harvey Richer of the University of British Columbia led the study, which began as an investigation of a globular star cluster in the Milky Way galaxy known as NGC 6397. ... Within the population of stars and galaxies behind NGC 6397, the Hubble image revealed a large elliptical galaxy that contains several hundred globular clusters. ... In fact, a single giant star in NGC 6397 appears 10 million times brighter than one of the distant globular clusters. ...

M1 image More About M1 Nice Color Picture . ... M16 image More About M16 HST image . ... M31 image More About M31 Nice Color Picture . ... M42 image ; M43 image More About M42/43 Nice Color CCD Picture . M51 image More About M51 Color Image of M51 M51 Supernova . M57 image More About M57 Nice Color CCD Picture Very Deep M57 Image . ... M81 image More About M81 M81 Supernova Ultraviolet Image of M81 More about Ultraviolet Imaging . M82 image More About M82 M82 False Color M82 True Color . ...

Amalthea . Jupiter V . Amalthea [am-al-THEE-uh] is one of Jupiter's smaller moons. ... These four images of Jupiter's moon, Amalthea, were taken by Galileo's solid state imaging system at various times between February and June 1997. ... Amalthea, whose longest dimension is approximately 247 kilometers (154 miles) across, is tidally locked so that the same side of the satellite always points towards Jupiter, similar to how the near side of our own Moon always points toward Earth. ...

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In autumn 1994, two groups of astronomers announced that they had discovered Cepheid variable stars in a distant cluster of galaxies. ... As the term suggests, variable stars change in brightness over time. ... Variable stars are an ideal way to get high-school students doing real science, with real data, from the real sky. ... a sky chart to find the stars . ... Students can use the nearby stars to estimate the magnitude of Delta. ... Locate the star Delta in Cepheus and estimate its brightness . ...

Supernova 2009js in NGC 918 . This page is devoted to information on Supernova 2009js in NGC 918 . Basic information on this SN, including the last reported brightness, on this Supernova can be found on the main page . Information on the original web pages for many of these images can be found on the updates and links web pages. Discovered independently by Lick Observatory Supernova Search (USA) and Koichi Itagaki (Japan). ... 2009/10/11.44 . 17.2 . ... Joseph Brimacombe . ...

Amalthea . Jupiter V . Amalthea [am-al-THEE-uh] is one of Jupiter's smaller moons. ... It was also the first moon of Jupiter to be discovered since Galileo's discovery of the four Galilean Moons in 1610. Amalthea is extremely irregular, having dimensions of about 270x165x150 kilometers in diameter. ... Discovered by . ... Topographic Map of Amalthea . ... As with all maps, it is the cartographer's interpretation; not all features are necessarily certain given the limited data available. ...

Astronotes Armagh Planetarium's Stellar Blog! ... Stars . ... Telescopes and Observatories . ... The majestic star-forming