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Pictures of the day

"I want to know why the universe exist, why there is something greater than nothing."

Steven Hawking

Scientist, Space Lover

ROSAT Explores The X-Ray Sky

Launched in 1990, the orbiting ROSAT observatory explored the Universe by viewing the entire sky in x-rays -- photons with about 1,000 times more energy than visible light. This ROSAT survey produced the sharpest, most sensitive image of the x-ray sky to date. The all-sky image is shown with the plane of our Milky Way Galaxy running horizontally through the center. Both x-ray brightness and relative energy are represented with red, green, and blue colors indicating three x-ray energy ranges (from lowest to highest). Bright x-ray spots near the galactic plane are within our own Milky Way. The brightest region (right of center) is toward the Vela Pulsar and the Puppis supernova remnant. Bright sources beyond our Galaxy are also apparent, notably the Virgo cluster of galaxies (near top right) and the Large Magellanic Cloud (LMC). The LMC is easy to find here as several of the black stripes (blank areas caused by missing data) seem to converge on its position (lower right). Over large areas of the sky a general diffuse background of x-rays dominates. Hot gas in our own Galaxy provides much of this background and gives rise to the grand looping structures visible in the direction of the galactic center (image center). Unresolved extragalactic sources also add to this background, particularly above and below the plane. Despite the x-ray sky's exotic appearance, a very familiar feature is visible - the gas and dust clouds which line the plane of our galaxy absorb x-rays as well as optical light and produce the dark bands running through the galactic center.

Boosting Compton Credit:

ven great observatories need a boost from time to time -- including the orbiting Compton Gamma-Ray Observatory. Sparkling reflections and the bright limb of the Earth are visible in this 1991 window view of Compton's release into orbit by the crew of the Space Shuttle Atlantis. Named after the American Nobel-prize-winning physicist, Arthur Holly Compton, the Compton Observatory has spent the last 6 years making spectacular discoveries while exploring the Universe at extreme gamma-ray energies. From its post over 240 miles above the Earth's surface, the 17 ton satellite still experiences enough atmospheric drag to cause its orbit to deteriorate over time. But NASA controllers have just completed a complex two month long series of firings of Compton's on-board thrusters which has raised its orbit to an altitude of over 300 miles. This reboost (Compton's second in 6 years) should allow it to continue its voyage of exploration of the distant high-energy Universe until about 2007. What if you could see gamma rays?

One Small Step

On July 20th, 1969, a human first set foot on the Moon. Pictured above is the first lunar footprint. The footprint and distinction of the first person to walk on the Moon belong to Neil Armstrong. It has been estimated that one billion people world-wide watched Armstrong's first step - making the live transmission from a camera mounted on the lunar lander one of the highest rated television shows ever. Upon setting foot on the moon, Armstrong said: "That's one small step for (a) man, one giant leap for mankind." The Apollo missions to the Moon have been described as the result of the greatest technological mobilization the world has known.



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