Mercury transiting Sun would be visible from India
India would have an opportunity to witness one of the rare astronomical events, the Mercury transit over the Sun's face on 9 May'16. Though it's expected to last for 7-and-half hours, it could be seen only for 2 hours and 45 minutes in India, from 4:41 pm onwards. The next Mercury transit would occur on 11 Nov'19 but, it wouldn't be visible from India.
What is transit of Mercury?
When the planet Mercury comes in between the Sun and the Earth, Mercury's transit across the Sun takes place, and it is visible as a tiny black dot moving across the Sun's face. Mercury transits visible from Earth are not very frequent; about 13-14 transits of Mercury occur in a century. Interestingly, Mercury transitions occur only in the month of May or November.
Watching the rare phenomenon from space
Mars rover Curiosity became the first celestial body besides Earth to witness the Mercury transit across the Sun on 3 Jun'14. In May, Mercury is near aphelion whereas in November it is near perihelion. Perihelion transits occur more frequently.
First observed transit of Mercury ever
Mercury transit across the Sun was first observed on 7 November 1631 by Pierre Gassendi from Paris, France. Johannes Kepler had predicted the transits of Mercury and Venus a little earlier before their occurrence. Gassendi had even attempted to observe the Venus transit in December 1631 but was unsuccessful as he was unaware that it wasn't visible from Paris because of inaccurate astronomical tables.
Mercury appears to graze the Sun
During some Mercury transits, the planet appears to graze the Sun during the transition. In this case, only some parts of the Earth can witness a full Mercury transit while some other parts can observe a partial transit.
Most of Asia can watch Mercury rising
Mercury transit would be visible to most Asian parts except south-eastern Asia and Japan. East Indian places could see the event for one hour while the west Indian places could see it for 2 hours and 45 minutes.
Sun shouldn’t be seen with naked-eye, emphasizes Ministry
Ministry of Earth Sciences noted that observing the rare Mercury transit without proper optical magnification would be difficult. The ministry emphasized that adopting safe techniques like telescope or binoculars with solar-filters or projecting the Sun's image on a whiteboard by telescope are advisable. In its note, the ministry added that the Sun should never be seen with the naked-eye as it leads to eye-damage.
Mars to also star in rare celestial sight
In May'16, Mars and Mercury would surprise sky-watchers as they both weren't seen in the past decade. After the Mercury transit, yellow-orange Mars would make its closest approach to the Earth (since 2005); but Indians can't observe the phenomenon.
Past and future Mercury passages visible from India
The astronomical phenomena would be visible on 9 May'16 in India after ten years; it had last occurred on 6 Nov'06, which was visible from extreme north-eastern parts of India. The next Mercury transit visible from India would occur after 16 years on 13 November 2032. In 2032, much of Asia, Australia, Europe, Africa, North and South America, etc. could observe the transit.