Transit Of Mercury- 2016


2016-03-23 08:21:55



‘Astronomy compels the soul to look upwards.’ It is the study and understanding of the universe beyond the planet Earth. It is impossible for anyone to rival the magnificence of universe. The astronomical bodies viz., Planets, Comets, Asteroids, Meteors, Nebulae, Stars and celestial manifestations like eclipses, occultations, transits, oppositions and planetary conjunctions absolutely reveal the magnanimity of astronomy. This year on May 9, Indians are really fortunate to witness the rare celestial spectacle ‘TRANSIT OF MERCURY’. On June 5, 2012, we were very fortunate to witness ‘TRANSIT OF VENUS’. This exceptional event definitely creates excitement and curiosity among us.

                 A ‘Transit’ is principally the passage of a celestial object (usually this presents a smaller angular size) in front of another object, presents a much larger angular size, as seen from Earth. In other words, a small celestial object will pass in front of a huge celestial object. On May 9, it is possible to witness the planet ‘Mercury’ passing in front of the massive and dazzling heavenly object ‘Sun.’ On Monday, May 9, 2016 Mercury will transit the Sun for the first time since 2006. The transit or passage of a planet across the face of the Sun is a relatively rare occurrence. As seen from Earth, only transits of Mercury and Venus are possible. There are approximately 13 to 14 transits of Mercury each century. In comparison, transits of Venus occur in pairs with more than a century separating each pair.




                   The first observation of a transit of Mercury was on November 7, 1631 by Pierre Gassendi (1592-1655). He unsuccessfully attempted to observe the transit of Venus just one month later, but due to inaccurate astronomical tables he did not realize that it was not visible from most of Europe, including Paris. Jeremiah Horrocks did not observe a transit of Venus until 1639. Edmond Halley first realized that transits could be used to measure the Sun's distance, thereby establishing the absolute scale of the solar system from Kepler's third law. Unfortunately, his method is somewhat impractical since contact timings of the required accuracy are difficult to make. Nevertheless, the 1761 and 1769 expeditions to observe the transits of Venus gave astronomers their first good value for the Sun's distance. Transits also served to give early scientists one of their first reliable measure of celestial distance. In 1716, Edmond Halley described how transits could be used to measure the Sun's distance, thus establishing the absolute scale of the solar system from Kepler's third law.


                A Transit of Mercury across the Sun takes place when the planet Mercury comes between the Sun and the Earth, and Mercury is seen as a small black dot moving across the face of the Sun. A transit of mercury over the disc of the Sun will occur on May 9 from 16 h 42 m 19 s (evening 4 hours 42 minutes) to May 10, 00 h 09 m 11 s (midnight 12 hours 09 minutes). The transit will be visible from most of Asia, Africa, Europe, Greenland, North and South America, Atlantic and Pacific oceans. In India, the beginning of the event will be visible from all places but the ending of the vent will not be perceptible from any place of India as the same will be in progress after sunset. Transits of Mercury can happen in May or November. November transits occur at intervals of 7, 13, or 33 years; May transits only occur at intervals of 13 or 33 years. The previous transits were in 1999, 2003, and 2006.


        The beginning of the transit comprising Ingress, exterior contact and Ingress- Interior contact will be visible in India since the Sun will rise after the occurrence of the phenomenon. The ending of the transit comprising Egress- Interior contact and Egress exterior- contact will not be visible from any part of India where the Sun will rise while the transit is in progress.

Geocentric Phases of the 2016 Transit of Mercury


Indian Standard Time

Position Angle




Contact 1


83.2 degrees

Contact 2


83.5 degrees

Greatest Transit


153.8 degrees

Contact 3


224.1 degrees

Contact 4


224.8 degrees



             Mercury is the closest planet to the Sun, making its highly elliptical orbit in only 88 days, moving faster than any other planet in the solar system. Since the heavily cratered planet is so close to the Sun, it’s rare to see it except during twilight. It was only 40 years ago that astronomers thought that the same side of the planet always faced the Sun. We now know that Mercury makes three rotations for every two orbits, making a Mercury day equal to nearly 59 Earth days. On Monday, May 9 and 10, the planet Mercury (as seen from Earth) will cross (transit) the face of the Sun. And with safe solar filtration on a telescope, we can see Mercury, as few ever will. It will be third of only fourteen such transits to occur in this century, the last being in 2006. During the transit the diameter of Mercury looks very small as it quickly moves (transits) across the Sun. The entire transit event lasts approximately 6 hours.

              Hence on May 9, it is possible for entire part of India to witness this exquisite manifestation. If we forget to see this, then we should wait till November 11, 2019 and cannot be seen from India at all. The simultaneous occurrence of a transit of Mercury and a transit of Venus is extremely rare, and will next occur only in the years 69163 and 224508. The simultaneous occurrence of a solar eclipse and a transit of Mercury is very rare. The next solar eclipse occurring during a transit of Mercury will be on July 5, 6757, and will be visible in Eastern Siberia. Enjoy this rare celestial display on May 9.