Wednesday, May 30, 2012

How to see the Venus transit

Whatever method you choose to observe this historical event, please be extremely cautious. NEVER look at the Sun with your naked eye or through ordinary sunglasses, and especially not through an unprotected telescope – this will cause permanent blindness. Instead, use one of these tried and tested methods:

Solar shades
For those with keen eyesight, the transit will be resolvable with a pair of ‘eclipse shades’, which have a special filter to permit safe, direct viewing of the Sun. However, subtle features such as the black drop effect will not be visible without magnification.  Do NOT use these glasses to filter sunlight through a telescope eyepiece – the intensity will be too strong to protect your eyes.

One can ask for the solar shade from auther before 5 June. Rupees 50 only.

Pinhole projection
Projecting a magnified view of the Sun through a telescope or binoculars onto a piece of white card (taking care to avoid overheating of the instrument optics by giving them a break every now and then) will provide a safe and satisfying view of the transit and will allow a group of people to admire the transit at the same time. 

It is also possible to project an unmagnified view of the Sun without the need for a telescope or binoculars, although finer details of the transit will not be resolvable.

Solar telescope
The transit is undoubtedly best viewed when magnified, either through a specially designed solar telescope or through a telescope fitted with a solar filter (although do not use filters that fit over the eyepiece – these can shatter under concentrated sunlight). Be sure to cap the finderscope, too; to safely find the Sun, orientate it such that the shadow of the telescope is at its smallest.

Live webcast
Various Planetary Organisations in india are planning the telecast the event on their website.  

Rare transit of Venus to be visible 5-6 June

Venus will cross the face of the Sun on 5-6 June, a rare occurrence that will not be seen again for over a hundred years.

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.

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.

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

For the India, the transit will begin in the around 3:39am on 6 June.