TECHNOLOGY: Venus makes last in a lifetime move across face of sun!

CAPE
CANAVERAL, Florida (Reuters) - The planet Venus made a slow transit
across the face of the sun on Tuesday, the last such passing that will
be visible from Earth for 105 years.
Transits of Venus happen in
pairs, eight years apart, with more than a century between cycles.
During Tuesday's pass, Venus took the form of a small black dot slowly
shifting across the northern hemisphere of the sun.






Armchair
astronomers watched the six-hour and 40-minute transit on the Internet,
with dozens of websites offering live video from around the world.
Closeup
views from the Prescott Observatory in Arizona, fed into Slooh.com's
webcast, showed a small solar flaring in the making just beneath Venus'
sphere.
Tuesday's transit, completing a 2004-2012 pair, began at 6:09 p.m. EDT (2209 GMT).
Skywatchers
on seven continents, including Antarctica, were able to see all or part
of the transit. Even astronauts aboard the International Space Station
joined in the spectacle.
"I've been planning this for a while,"
space station flight engineer Don Pettit said in a NASA interview. "I
knew the transit of Venus would occur during my rotation, so I brought a
solar filter with me."
It's not all about pretty pictures.
Several science experiments were planned, including studies that could
help in the search for habitable planets beyond Earth.
Telescopes,
such as NASA's Kepler space telescope, are being used to find so-called
extrasolar planets that pass in front of their parent stars, much like
Venus passing by the sun.
During the transit of Venus, astronomers
planned to measure the planet's thick atmosphere in the hope of
developing techniques to measure atmospheres around other planets.
Studies
of the atmosphere of Venus could also shed light on why Earth and
Venus, which are almost exactly the same size and orbit approximately
the same distance from the sun, are so different.
Venus has a chokingly dense atmosphere, 100 times thicker than Earth's, that is mostly carbon dioxide, a greenhouse gas.
Its
surface temperature is a lead-melting 900 degrees Fahrenheit (480
degrees Celsius) and towering clouds of sulfuric acid jet around the
planet at 220 miles per hour dousing it with acid rain.
"Venus is
known as the goddess of love, but it's not the type of relationship
you'd want," an astronomer said on the Slooh.com webcast. "This is a
look-but-don't-touch kind of relationship."
Scientists are interested in learning more about Venus' climate in hopes of understanding changes in Earth's atmosphere.

















During
previous transits of Venus, scientists were able to figure out the size
of the solar system and the distance between the sun and the planets.
Tuesday's
transit is only the eighth since the invention of the telescope, and
the last until December 10-11, 2117. It also is the first to take place
with a spacecraft at Venus.
Observations from Europe's Venus
Express probe will be compared with those made by several ground and
space-based telescopes, including NASA's Solar Dynamics Observatory, the
joint U.S.-European Solar and Heliospheric Observatory and Japan's
Hinode spacecraft.