Get Ready for the Transit of Venus!




http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50390

Get ready for the transit of Venus!
European Space Agency
24 May 2012

Scientists and amateur astronomers around the world are preparing to
observe the rare occurrence of Venus crossing the face of the Sun on 5-6
June, an event that will not be seen again for over a hundred years.

The occasion also celebrates the first transit while there is a
spacecraft orbiting the planet - ESA's Venus Express.

ESA will be reporting live from the Arctic island of Spitsbergen, where
the Venus Express science team will be discussing the latest scientific
results from the mission while enjoying a unique view of the 2012
transit under the 'midnight Sun'.

A transit of Venus occurs only when Venus passes directly between the
Sun and Earth. Since the orbital plane of Venus is not exactly aligned
with that of Earth, transits occur very rarely, in pairs eight years
apart but separated by more than a century.

The last transit was enjoyed in June 2004 but the next will not be seen
until 2117.

Venus transits are of great historical significance because they gave
astronomers a way to measure the size of the Solar System.

The transits of the 18th century enabled astronomers to calculate the
distance to the Sun by timing how long it took for Venus to cross the
solar disc from different locations on Earth and then using simple
trigonometry.

Also, during the transit of 1761 astronomers noticed a halo of light
around the planet's dark edge, revealing Venus to have an atmosphere.

Thanks to spacecraft that have since visited Venus, including Venus
Express, we now know that it hosts an inhospitable dense atmosphere of
carbon dioxide and nitrogen with clouds of sulphuric acid.

Today transit events are a valuable tool for developing methods for
detecting and characterising planets orbiting other stars than the Sun,
planets that astronomers refer to as exoplanets.

As a planet passes in front of a star, it temporarily blocks out a tiny
portion of the starlight, revealing its presence and providing
information about the planet's size. Europe's CoRot space telescope has
used this technique to discover over 20 exoplanets.

Transits are also being used to search for exoplanets that may harbor
life. If the planet has an atmosphere a small fraction of the light from
the star will pass through this atmosphere and reveal its properties,
such as the presence of water or methane.

During next month's transit, astronomers will have the chance to test
these techniques and add to the data collected during only six previous
Venus transits observed since the invention of the telescope in the
early 1600s.

The 2012 transit will be visible in its entirety only from the western
Pacific, eastern Asia, eastern Australia and high northern latitudes.

For the US, the transit will begin in the afternoon of 5 June and for
much of Europe the Sun will rise on 6 June with the transit almost
finished. If you are observing the event please remember - NEVER look at
the Sun with unprotected eyes, through ordinary sunglasses or through a
telescope, as this will cause permanent blindness.

The Sun does not set at Spitsbergen in June, providing a unique
opportunity to observe the entire transit from 22:04 GMT 5 June (00:04
CEST 6 June) to 04:52 GMT (06:52 CEST).

"We're very excited about watching the transit from such a unique
European location while Venus Express is in orbit around the transiting
planet," says HÃ¥kan Svedhem, ESA's Venus Express project scientist.

"During the transit, Venus Express will make important observations of
Venus' atmosphere that will be compared with ground-based telescopes to
help exoplanet hunters test their techniques."

As ESA prepares for this rare event with observations from space and
from the ground, we will provide background information about the
transit on a dedicated blog <http://blogs.esa.int/venustransit/>.

Live updates will be posted from Spitsbergen during 5-6 June as the
world tunes in to watch Venus make its journey across the Sun for the
last time this century.

Contact for further information:

Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Email: markus.bauer@xxxxxxx
Tel: +31 71 565 6799
Mob: +31 61 594 3 954

Hakan Svedhem
ESA Venus Express Project Scientist
Email: hakan.svedhem@xxxxxxx

(This article was originally published on ESA's Space Science Portal
<http://www.esa.int/export/esaSC/SEMLSGZWD2H_index_0.html>.)

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