Galaxies Cluster Toward the Great...
Galaxies dot the sky like jewels in the direction of a mass so large it is known simply as the Great Attractor. The galaxies pictured above are part of a cluster of galaxies called ACO 3627 near the center of the Great Attractor. Previously, ...
Cas A Supernova Remnant in X-Rays
The complex shell of a star seen to explode 300 years ago is helping astronomers to understand how that star exploded. The above recently released image of supernova remnant Cassiopeia A (Cas A) shows unprecedented detail in three X-ray colors. ...
The Largest Rock Known
There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid, moon, and comet nucleus. It is larger than any other rocky planet. (Nobody knows for sure what size rocks lie at the cores of Jovian ...
The Millennium that Defines Universe
Welcome to the millennial year at the threshold of millennium three. During millennium two, humanity continually redefined its concept of "Universe": first as spheres centered on the Earth, in mid-millennium as the Solar System, a few centuries ...
The Millennium that Defined Earth
When the second millennium began, people generally knew that the Earth was round, but few saw much of it beyond their local village. As the millennium progressed, humans mapped the continents, circumnavigated the globe, and determined the ...
The Century that Defined Galaxy
As the twentieth century dawned a debate raged over whether the Milky Way was the entire universe. The 1920s brought observations of spiral-nebulae that housed familiar but faint variable stars, and hence placed these nebulae much farther than ...
The Decade that Defined Star System
As the 1990s began, the only planetary star system known was our own Solar System. The first extra-solar star system was discovered orbiting a pulsar in 1991. Slight changes in the precise arrival times of the pulses from the central small ...
A Year Of New Perspectives
Fittingly, 1999 saw a decade of astronomical discoveries to an end with portents of things to come - embodied in new spacecraft, telescopes, and perspectives to explore the distant Universe across the electromagnetic spectrum. X-ray astronomy in ...
Solar Moss
Discovered in recent close-up pictures of the Sun from NASA's Transition Region And Coronal Explorer (TRACE) spacecraft, this spongy-looking stuff has a temperature of 2 million degrees Fahrenheit ... and has been dubbed "Solar Moss". The ...
West Of The Great Red Spot
The turbulent region West of Jupiter's Great Red Spot is highlighted in this picture constructed from data recorded by the Galileo spacecraft. The image is color coded to show cloud height and thickness; white clouds are high and thick, light ...
