Here is a once a life time opportunity to view a celestial spectacle. On June 6, the planet Venus will pass across the disc of the Sun. The event is known as the transit of Venus.
It is not just a rare occurrence, but astronomers say historically it helped in measuring the size of the solar system. Transits of planets across the Sun do not take place frequently, compared to say eclipses.
Since the Earth is the third planet from the Sun, the transit can be observed only for the inner planets of the solar system — Mercury and Venus. The transit of Mercury occurs 13-14 times in a century, but in the case of Venus it is extremely rare, says Prof. P. Vivekananda Rao, Head, Department of Astronomy, Osmania University.
The transit of Venus occurs in pairs, separated by eight years. The first transit occurred on June 8, 2004 and the second of this pair will be on June 6. This pattern is repeated after periods of 105.5 and 121.5 years, he said.
The Astronomy Department in collaboration with the Vigyan Prasar, Department of Science & Technology are conducting a three-day workshop to science communicators and popularisers during May 7-9 here. It will discuss the scientific aspects and safe ways of viewing the transit. Well-known astrophysicist Prof. Jayanth Murthy of Indian Institute of Astrophysics, Bangalore, will take part in the workshop.
As for viewing, one must never view the Sun through a telescope or the naked eye. The transit should be seen through approval solar goggles and filters. The better way would be to project on to a screen with a telescope. The transit appears like a small spot when viewed from the Earth.
Well-known astronomer, Edmund Halley in 1716 said that by observing the transit from two different places one could accurately find the distance between the Earth and Sun. A transit of Venus illustrates the method by which astronomers now searching for planets in the habitable zone around distant stars, Prof Rao said.