Around 100 curious onlookers turned up at the Anna Science Centre-Planetarium in the city to view the rare ‘transit’ of the planet Mercury across the Sun on Monday.
Arrangements were made for people to view the transit through a telescope fitted with sun-spotter screen.
The centre had arranged for the public to view live streaming of the event on YouTube, with the help of four students belonging to the Nakshatra astronomy club of the National Institute of Technology, Tiruchi (NITT).
The event is considered rare because of the alignment between the Sun, Mercury and the Earth that allows the phenomenon to be seen with better visibility.
“Throughout the year, Mercury can usually be seen at sunset or sunrise, because it goes along with the Sun, and is on the horizon. But the May 9/10 occurrence is the best time to see Mercury up on the disk of the Sun,” I. K. Lenin Tamilkovan, project director, Anna Science Centre-Planetarium, told The Hindu .
As the public gathered eagerly around the centre’s 5-inch telescope yesterday, they were able to see Mercury as a tiny black speck moving steadily across the Sun.
However, Mr. Tamilkovan said that because it wasn’t safe to expose the eyes to the direct light of the Sun, the event had to be viewed on a sun-spotter screen, which had the planetary journey projected on it.
The time it takes Mercury to move across the Sun varies, and is dependent on the momentary velocity of the planet in its orbit and on the exact path across the Sun. A transit may last up to nine hours.
On average, there are 13 Mercury transits each century. But they do not occur at regular intervals. Each year, the Earth passes Mercury’s line of nodes around May 7 and November 9, according to Planetarium authorities.
Mercury is also the fastest-moving planet in the solar system. During this year’s transit, it was estimated that the planet would take 7.5 hours to cross the face of the Sun at a speed of 30 miles (48 km) a second.
Those who missed the event in Tiruchi have a long wait ahead – astronomers say the next such Mercury transit that can be viewed fully in India will occur on November 13, 2032. The November 11, 2019 transit will not be visible from Tamil Nadu.
Pudukottai
A large number of persons, particularly students, witnessed the transit of the planet Mercury across the Sun for about 40 minutes from 5-10 p.m. on Monday, using telescope at a programme organised by the district branch of the Tamil Nadu Science Forum. M. Veeramuthu, district secretary and S. T. Balakrishnan, state secretary, explained the significance of the phenomenon during the course of observation.
