July 10 2013 Astronomy Newsletter
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Water on the Moon
Everybody had known for a long time that the Moon was bone dry. In the nineties probes found some evidence of water. After a big announcement of water on the Moon, it went back again to being described as dry. What's the story in the 21st century?
*Galaxy Evolution Explorer (GALEX)*
On June 28 NASA turned GALEX off, after ten years of studying galaxies in the ultraviolet. Missions aren’t designed to last this long, but after completing the prime objectives, the mission was extended three times. We get a whole different idea of galaxies in the ultraviolet compared to what our own eyes can see. Here is an example of the same galaxy photographed in two different wavelengths of light: http://pinterest.com/pin/250090585529737949/
Last year, in a unique move, NASA loaned the spacecraft to Caltech. Caltech used private funding to continue to operate it, though NASA still owned GALEX. Eventually GALAX’s orbit will decay so that it falls back to Earth and burns up as it re-enters the atmosphere. That won’t happen for another six or seven decades.
*Telstar – the revolution*
On July 10, 1962 a revolution began, for on this day 51 years ago the global communications age began. Telstar 1 was launched. It connected North America with Europe, and could actively relay television, telephone and picture fax messages. But only for about twenty minutes a day. Modern communications satellites are in geosynchronous orbits, so they keep up with the rotating Earth and stay in the same relative position above Earth. Telstar was in low Earth orbit and could only transmit between North America and Europe for the short time it was over the Atlantic.
Telstar 1 was the first big step towards creating the world we know today. It stopped working within a year of its launch, due to radiation damage, but it's still in orbit.
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I wish you clear skies.
Mona Evans, Astronomy Editor
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