From: Paul Doherty (pauld@exploratorium.edu)
Date: Tue May 06 2003 - 11:18:54 PDT
Message-Id: <l0311072bbaddacfd59e5@[192.168.111.161]> Date: Tue, 6 May 2003 11:18:54 -0700 From: Paul Doherty <pauld@exploratorium.edu> Subject: More info on mercury transit
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>Date: Fri, 2 May 2003 09:20:36 -0400 (EDT)
>From: NASANews@hq.nasa.gov
>Subject: NASA OBSERVATORY TRACKING RARE SOLAR EVENT
>Sender: owner-press-release@spinoza.public.hq.nasa.gov
>To: undisclosed-recipients:;
>
>Nancy Neal
>Headquarters, Washington May 2, 2003
>(Phone: 202/358-2369)
>
>Bill Steigerwald
>Goddard Space Flight Center, Greenbelt, Md.
>(Phone: 301/286-5017)
>
>RELEASE: 03-152
>
>NASA OBSERVATORY TRACKING RARE SOLAR EVENT
>
> The planet Mercury will pass in front of the sun on
>Wednesday, May 7 in an unusual event called a transit.
>NASA's Solar and Heliospheric Observatory (SOHO) spacecraft
>offers excellent, safe views of the rare occurrence to
>anyone with an Internet connection.
>
>"People will see a small, perfectly round, black dot slowly
>moving across the solar disk," said eclipse expert Fred
>Espenak of NASA's Goddard Space Flight Center, Greenbelt,
>Md.
>
>Mercury transits are rare, occurring only approximately a
>dozen times per century. Observers in Asia, Africa and
>Europe will have the best view of this transit, which will
>already be in progress as the sun rises over America
>(approximately 6 a.m. EDT).
>
>The transit can't be seen with the unaided eye, since
>Mercury's apparent size is only about 1/160 of the sun's
>diameter. Direct telescope viewing is not recommended, since
>special precautions must be taken to avoid permanent eye
>damage.
>
>Although the entire transit lasts over five hours, viewers
>in North America will only see the last 20 to 30 minutes of
>it. The event will be finished by the time the sun rises
>west of a line from the Great Lakes to the Carolinas, but
>the complete transit is safely viewable on the SOHO Web site
>at:
>
>http://soho.nascom.nasa.gov/hotshots/2003_05_07/
>
>SOHO orbits a special point in space one million miles
>(about 1.6 million kilometers) from Earth, in line with the
>sun, to make continuous observations of solar activity. One
>of its instruments, the Large Angle and Spectrometric
>Coronagraph, will be able to see Mercury a few days before
>it transits the sun. Other instruments will track Mercury's
>progress across the solar disk during the transit. The
>pictures will be available almost immediately on the SOHO
>Web site. The SOHO mission is a project of international
>cooperation between NASA and the European Space Agency.
>
>The planets Mercury and Venus are the only ones that appear
>to cross the face of the sun, as seen from Earth, since both
>are closer to the sun than Earth. Venus transits are also
>extremely rare, with just one pair eight years apart every
>105 to 121 years.
>
>"The last Venus transit was in 1882, so no one alive has
>seen one," said Espenak. "Happily, there will be a Venus
>transit June 8, 2004, so this year's Mercury transit can be
>taken as an appetizer for the main course."
>
>The transits were important historically. "Venus transits
>were the Apollo project of the 18th and 19th centuries," said
>Espenak. "There were major international efforts, with
>scientific expeditions to remote corners of the world, in
>order to measure the apparent position of Venus on the solar
>disk. Using trigonometry and a careful analysis of
>observations, astronomers could determine the actual
>distances to Venus and the sun. Captain James Cook, the
>legendary British navigator and explorer, recorded the
>transit of Venus from Tahiti in 1769. The observation was a
>major motivation for his expedition to the South Pacific and
>the circumnavigation of the globe," Espenak explained.
>
>For more information about transits of Mercury and Venus,
>including photographs, refer to:
>
>http://sunearth.gsfc.nasa.gov/eclipse/transit/transit.html
>
>For information on the Internet about Captain Cook's
>expedition, visit:
>
>http://www.geocities.com/TheTropics/7557/cook.html
>
>For recommended safe telescope viewing instructions, refer
>to:
>
>http://skyandtelescope.com/observing/objects/planets/article
>_921_1.asp
>
>
>
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>
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