View the Transit of Venus on Wednesday from White Hall

GANGTOK, 04 June: The transit of Venus on 06 June is the perhaps the only chance for most of us in this lifetime to view this special celestial event which will occur next after 105.5 years!
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk, and can be seen from Earth as a small black disk moving across the face of the Sun.
Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years.
The transit will be best viewed from the Pacific Ocean. North America will be able to see the start of the transit, while South Asia, the Middle East, and most of Europe will catch the end of it. The transit will not be visible in most of South America or western Africa. From India, you will be able to see the latter part of it as it would have started before sunrise.
Enthusiasts, astronomers and the science community across the globe are gearing up for this rare event. In India, SPACE, Science Popularisation Association of Communicators and Educators, is organising a host of activities on the Venus transit. SPACE is an NGO based in Delhi, founded in 2001, with the goal of popularizing science via Astronomy and Space Sciences throughout the domains of education, public and media.
On 06 June, SPACE is conducting public observations at Jantar Mantar, New Delhi, at the Udaipur Solar Observatory, Udaipur and one at Tihar Jail especially for the prison staff. Live webcast of the transit from start to end (Ingress to Egress) is also being organised [http://www.space-india.org/transit-of-venus/webcasting.html], in case weather conditions do not allow a clear view. Similar observations have also been planned in schools in and around Delhi apart from its associate schools across the country.
Here in Sikkim, the State Council of Science & Technology is organising a public observation at White Hall premises, Gangtok on 06 June and the Council has invited all interested to participate in the event. The Council is also organising awareness programme along with series of lectures in Sikkim Science Centre, Marchak and some of the schools on 05 June at 10 am. According to the Council, in Gangtok the transit of Venus will be visible from 10:04:11 in the morning.

TRANSIT TIMINGS

Transit of Venus is a very rare occasion and if you are planning not to miss this amazing celestial event then here is the table to show you the timings of 1st contact (External Ingress), 2nd contact (Internal Ingress), 3rd contact (Internal Egress), 4th contact (External Egress) from various cities in India. However, since in India transit is visible during the sunrise, we would have already missed 1st and 2nd contact as at that time India will be in the night side of Earth. The timings marked with * are the contacts not visible from individual cities due to night time.

A table showing the timings in Gangtok is given below:

Sunrise	External Ingress	Internal Ingress	Maximum Transit	Internal Egress	External Egress
04:40:17	03:40:10*	03:57:57*	07:02:16	10:04:05	10:21:24

[courtesy: SPACE]

The Venus transit has special significance also because when observed with sufficient accuracy from the Earth it allows the determination of the distance between the Earth and the Sun. This measure is crucial for astronomers to know because all other distance determinations in the universe ultimately depend on this value. Today astronomers use other, more precise methods for the determination of this “Astronomical Unit – AU”, so the present one is above all of historical and didactic interest.
Scientist all over the world will use this rare celestial phenomenon to measure the distance between Earth and Sun – 1 A.U.
The next transits of Venus will be on in December 2117 and December 2125.

VIEWING THE VENUS TRANSIT

The safest way to watch a transit is to observe an image of the Sun projected onto a screen through a telescope, binoculars, pinhole or reflected pinhole. The event can be viewed without magnification using filters specifically designed for this purpose, such as an astronomical solar filter or eclipse viewing glasses coated with a vacuum-deposited layer of chromium. The once-recommended method of using exposed black-and-white film as a filter is not now considered safe, as small imperfections or gaps in the film may permit harmful UV rays to pass through. Observing the Sun directly without appropriate protection can damage or destroy retinal cells, causing temporary or permanent blindness. It is advisable not to use smoked glass, colour film, sun glasses exposed black and white film photographic neutral density filters and polarizing filters. They all are unsafe.

[Sikkim State Council of Science and Technology]