Jardin

Venus starts its rare Sun transit

By Jonathan Amos
Science correspondent, BBC News
Venus (top left) seen by Nasa's Solar Dynamics Observatory moving on to the face of the Sun
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Planet Venus is putting on a show for skywatchers, moving across the face ofthe Sun as viewed from Earth.
The transit is a very rare astronomical event that will not be seen again for another 105 years.
Observers in north and central America, and the northern-most parts ofSouth America saw the transit begin just before local sunset.
The far northwest of America, the Arctic, the western Pacific, and east Asia will witness the entire passage.
The UK and Europe, theMiddle East, and eastern African must wait for local sunrise to see the closing stages of the transit.
Venus appears as a small black dot moving slowly but surely across the solar disc.
Some of thebest pictures of the event have been provided by the US space agency's (Nasa) Solar Dynamics Observatory, which studies the Sun from a position 36,000km above the Earth.
"We get to see Venus inexquisite detail because of SDO's spatial resolution," said astrophysicist Dr Lika Guhathakurta.
"SDO is a very special observatory; it takes images that are about 10 times better than a high-definition TVand those images are acquired at a temporal cadence of every 10 seconds. This is something we've never had before."
Scientists are observing the transit to test ideas that will help them probeEarth-like planets elsewhere in the galaxy, and to learn more about Venus itself and its complex atmosphere.
These researchers are equipped with specialist equipment which allows them to look directly atthe solar disc.
Ordinary members of the public are advised to take extreme care in viewing the transit.
Looking directly at the Sun with the naked eye, or worse still through an open telescope or...