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July
3, 2009: If you've never seen a spaceship with your
own eyes, now's your chance.
The
International Space Station (ISS) is about to make a remarkable
series of flybys over the United States. Beginning this 4th
of July weekend, the station will appear once, twice, and
sometimes three times a day for many days in a row. No matter
where you live, you should have at least a few opportunities
to see the biggest spaceship ever built.
Check
NASA's
ISS Tracker for flyby times.
Above:
In bright evening twilight, the International Space Station
soars over Hawaii's Kilauea Volcano on June 3, 2009. Image
credit and copyright: Stephen O'Meara. Used with permission.
[larger image]
The
ISS has been under construction for nearly 11 years, and it
has grown very large and very bright. The station is now more
than 350 ft wide (wider than a football field), has 12,600
cubic feet of labs and living quarters, and on Earth would
weigh about 670,000 lb. Sunlight illuminating the massive
outpost makes it shine fifteen times brighter than Sirius,
the brightest star in the sky.
Sometimes
it is even brighter than that. Sunlight glinting from the
station's flat surfaces (mainly solar arrays) produce dazzling
flares as much as six hundred times brighter than Sirius.
For astronomers: On the scale of visual magnitudes, space
station flares register -8.
"The
station flared spectacularly on May 22nd when it passed over
my backyard observatory in the Netherlands," reports
amateur astronomer Quintus Oostendorp. "I knew the ISS
was coming, so I had my telescope ready and I was able see
exactly what happened." Click on the image to launch
a movie he recorded through his 12-inch Newtonian reflector:
Above:
Sunlight glints from the space station's solar arrays on May
22, 2009. Photo credit: Quintus Oostendorp of Vaassen, the
Netherlands. [larger
still image] [movie]
At
present, the flares are unpredictable. No one knows when they
will happen or exactly how bright they will be. Any given
flyby could be interrupted by one—and that's what makes the
watch so much fun.
The
marathon of space station flybys won't stop until mid-to-late
July (depending on your location). That gives space shuttle
Endeavour, currently scheduled to launch on July 11th, time
to reach the space station and join the show. As the shuttle
approaches station for docking, many observers will witness
a memorable double flyby—Endeavour and the ISS sailing side
by side across the starry night sky.
Endeavour
is on yet another space station construction mission. This
time it will deliver a "space porch" to be added
to Japan's Kibo science laboratory module. The porch is not
a place where astronauts can sit, relax and watch the stars
drift by (although that is not a bad idea); it is a science
platform. When an experiment needs to be exposed to the hard
vacuum or energetic radiation of space, it can placed outside
on the porch to take advantage of the space station's unique
research environment. The official name of the porch is the
Kibo Japanese Experiment Module Exposed Facility and it will
add its own small contribution to the station's reflected
luminosity in the night sky.
What
now? Check for flyby times, ready your telescope (optional),
and let the sightings begin.
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Author: Dr.
Tony Phillips | Credit: Science@NASA
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