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"I want to know why the universe exist, why there is something greater than nothing."
Steven Hawking
Scientist, Space Lover
The unremarkable star centered in this skyview is Gliese 581, a mere 20 light-years away toward the constellation Libra. But astronomers are now reporting the discovery of a remarkable system of three planets orbiting Gliese 581, including the most earth-like planet found beyond our solar system. Gliese 581 itself is not a sun-like star, though. Classified as a red dwarf, the star is much smaller and colder than the Sun. Still, the smallest planet known to orbit the star is estimated to be five times as massive as Earth with about 1.5 times Earth's diameter. That super-earth orbits once every 13 days, about 14 times closer to its parent star than the Earth-Sun distance. The close-in orbit around the cool star implies a mean surface temperature of between 0 and 40 degrees C - a range over which water would be liquid - and places the planet in the red dwarf's habitable zone.
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. The Earth's daytime sky appears blue for the same reason. The red and yellow regions shine primarily because of emission from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares - knocks electrons away from the gas, which then shines when the electrons recombine with the gas. The dark brown regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. The Rho Ophiuchi star clouds, well in front of the globular cluster M4 visible here on the upper right, are even more colorful than humans can see - the clouds emits light in every wavelength band from the radio to the gamma-ray.
Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two celestial wonders easily visible for southern hemisphere skygazers are known as the Clouds of Magellan. These cosmic clouds are now understood to be dwarf irregular galaxies, satellites of our larger spiral Milky Way Galaxy. The Small Magellanic Cloud actually spans 15,000 light-years or so and contains several hundred million stars. About 210,000 light-years away in the constellation Tucana, it is more distant than other known Milky Way satellite galaxies, including the Canis Major and Sagittarius Dwarf galaxies and the Large Magellanic Cloud. This sharp image also includes two foreground globular star clusters NGC 362 (bottom right) and 47 Tucanae. Spectacular 47 Tucanae is a mere 13,000 light-years away and seen here to the left of the Small Magellanic Cloud. Take a short survey about viewing astronomy images on mobile devices.
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