Monday, January 31, 2011

A comet close enough to touch: some observers enjoy anout-of-this-world view.(viewing Comet Hale-Bopp from the space shuttle).

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* My own mission to Comet Hale-Bopp began with a liftoff on the space shuttle Columbia into beautiful clear blue skies at 2:20 p.m. EST on April 4, 1997. Our main reason for heading into space lay in the shuttle's Spacelab payload, but my crewmates and I were privileged to see Comet Hale-Bopp in between running experiments. On March 22, the comet was closest to Earth. A few days later, on April 1, it was closest to the sun and most active. This, combined with the darkness of a new moon on April 7, allowed near-perfect comet-viewing during the opening days of our flight.

My first view came 16 hours into the mission. About 15 seconds after sunset, Earth's atmosphere underwent a series of beautiful, subtle color changes, from bright gold to reddish-orange to deep blue to pitch black, all in just five minutes' time. After that, Earth's eerie airglow became visible. This thin layer of upper atmosphere gives off light on the dark side of Earth due to atoms, mainly oxygen and sodium, that are ionized by solar radiation.

As my eyes adjusted to the lower light level, I spotted Comet Hale-Bopp, above and to the left of where the sun had set. It was only slightly brighter than it had been from my backyard in Houston. But this view was much more spectacular because of the contrast against a pitch-black sky.

As I watched the comet and my eyes became even more dark-adapted, its brightness seemed to increase. In a matter of minutes, Hale-Bopp passed through the airglow layer; a few seconds later, it set into thicker layers of the atmosphere. Then, as if someone turned off a switch, the comet was gone, having set below Earth's limb.

I stared at the black sky for a few seconds more before I realized that I had just seen a comet set. Of the hundreds of astronauts and cosmonauts who have made the journey into space, only a select few have seen a comet's graceful form actually sink below Earth's limb.

But the best lay ahead.

On day three, our commander, Jim Halsell, mentioned that the ingenious folks at mission control had selected stars near Hale-Bopp for a routine guidance-system alignment. This would allow us to point the shuttle directly at the comet for about 30 minutes ... perfect for photographing the comet from orbit! Jim asked me to shoot this once-in-a-lifetime event.

I quickly made my preparations. I cleaned the right overhead window, mounted a camera loaded with ISO 1600 film onto a multipurpose adjustable arm, and shielded it from reflections that might be produced by interior lights or computer screens on the flight deck.

Finally the time had come. As we passed over the west coast of central Africa, I watched another spectacular sunset, and then clearly visible in the center of the window was Hale-Bopp. I began firing off pictures as fast as I could, bracketing at various shutter speeds until the comet set below the horizon. The pictures you see here are the best of my series.

While my photo frenzy was taking place, six other crewmembers had their noses pressed up against a neighboring overhead window. One hundred and sixty five miles below us were lightning flashes and agricultural fires in Africa, moving by at nearly five miles a second. The sky turned black once again as we headed out over the Indian Ocean. Then we turned from the comet.

Flight engineer Mike Gernhardt summed up our feelings of Hale-Bopp during a post-flight press conference. "To imagine that the last time human eyes saw that comet was when they were building the great pyramids 4,000 years ago makes you wonder what human civilization will be like the next time Hale-Bopp visits us. I'm certain that it will involve the colonization of space. The crew of STS-83 is really proud to have been a part of the baby steps we're taking in that direction."

Source Citation
Thomas, Don. "A comet close enough to touch: some observers enjoy an out-of-this-world view." Astronomy Oct. 1997: 121+. Academic OneFile. Web. 31 Jan. 2011.
Document URL

Gale Document Number:A19751202

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