The transit of Mercury over the disk of the Sun on Monday, May 9, 2016

A transit of Mercury over the disc of the Sun will take place in the afternoon of May 9, 2016 (19 Vaishakha, 1938 Saka Era). This transit phenomenon will be visible from India.

This phenomenon takes place when the planet Mercury will be seen as a small black dot travelling from one limb of the solar disc to the other.

From the Earth this phenomenon is seen when the Mercury passes between the Sun and the Earth. This happens only when the Sun, the planet Mercury and

the Earth are lined up in one plane. The Mercury appears as a dot on the solar disc because its angular size is very small compared to that of the Sun as seen

from the Earth.

The transit begins with Contact-I, the instant when the disc of the planet Mercury is externally tangent with the Sun (Ingress exterior) followed by Contact-II

when the Mercury is internally tangent with the Sun (Ingress interior). The Mercury will be seen as a black spot, traveling several hours over the face of the disc,

will reach the opposite limb of the Sun at Contact-III, when the disc of the planet Mercury is internally tangent with the Sun (Egress interior). Finally,

the transit ends at Contact-IV when the disc of the planet Mercury is externally tangent with the Sun (Egress exterior).

The phenomenon is a relatively rare one which occurs 13 or 14 times in a century. It occurs in the month of May and November. The interval between

one November transit and next November transit may be 7, 13 or 33 years whereas the interval between one May transit and the next May transit may be

13 or 33 years.

The transit of Mercury will be visible from most of Asia (except south eastern parts and Japan), Europe, Africa, Greenland, South America,

North America, Arctic, North Atlantic Ocean and most of the Pacific Ocean. The entire transit, from beginning to end, will be visible from eastern

North America, northern South America, the Arctic, Greenland, extreme northwestern Africa, western Europe, and the North Atlantic Ocean.

In India, the beginning of the event comprising of Ingress exterior (Contact-I) and Ingress interior (Contact-II) will be visible from all places. The duration of the

entire transit event will be about 7 hour and 30 minutes. The observer in India will not see the ending of the event as the same will be in progress after sunset.

Depending upon the sunset time of different places in India, the observer located in the extreme east of the country will see the event about 1 hour from

the beginning and the observer located in the extreme west of the country will see the event about 2 hours and 45 minutes from the beginning.

In Delhi, the event can be seen for a duration of about 2 hours 20 minutes as it will start at 16h 41m IST and sunset will take place at 19h 01m IST.

Similarly, in Kolkata the event will start at 16h 41m IST and it can be seen for a duration of about 1 hour 26 minutes, in Mumbai the event will start

at 16h 41m IST and it can be seen for a duration of about 2 hours 24 minutes, in Chennai the event will start at 16h 41m IST and it can be seen for a

duration of about 1 hour 45 minutes.

A table related to local circumstances of some places in India is appended below for ready reference.

LOCAL CIRCUMSTANCES RELATING TO CERTAIN PLACES IN INDIA

Place	Ingress Exterior contact	Ingress Interior contact	Egress Interior contact	Egress Exterior contact	Sunset	Duration
	h m s	h m s			h m	h m
Agartala	16 40 33.6	16 43 45.6			17 57	1 16
Ahmedabad	16 40 45.5	16 43 57.0			19 12	2 31
Aijawl	16 40 33.1	16 43 45.1			17 52	1 11
Ajmer	16 40 45.3	16 43 56.9			19 09	2 28
Allahabad	16 40 39.5	16 43 51.3			18 39	1 58
Amritsar	16 40 48.4	16 44 00.1			19 17	2 36
Bangalore	16 40 37.8	16 43 49.4			18 37	1 56
Bhagalpur	16 40 36.5	16 43 48.4			18 18	1 37
Bhopal	16 40 41.4	16 43 53.1			18 53	2 12
Bhubaneswar	16 40 34.5	16 43 46.3			18 15	1 34
Cannanore	16 40 39.5	16 43 51.0			18 44	2 03
Chandigarh	16 40 46.2	16 43 57.9			19 06	2 25
Chennai	16 40 35.8	16 43 47.4			18 26	1 45
Cochin	16 40 38.5	16 43 49.9			18 37	1 56
Cooch Behar	16 40 35.9	16 43 47.9			18 0 9	1 28
Cuttack	16 40 34.5	16 43 46.3			18 15	1 34
Darjeeling	16 40 36.9	16 43 48.9			18 15	1 34
Dehradun	16 40 45.0	16 43 56.7			19 01	2 20
Delhi	16 40 44.4	16 43 56.1			19 01	2 20
Dibrugarh	16 40 34.7	16 43 46.8			17 48	1 07
Dwarka	16 40 48.3	16 43 59.7			19 24	2 43
Gandhinagar	16 40 45.5	16 43 57.0			19 12	2 31
Gangtok	16 40 36.9	16 43 48.9			18 14	1 33
Gaya	16 40 37.2	16 43 49.0			18 25	1 44
Guwahati	16 40 35.0	16 43 47.0			18 01	1 20
Haridwar	16 40 44.7	16 43 56.4			19 01	2 20
Hyderabad	16 40 38.2	16 43 49.8			18 39	1 58
Imphal	16 40 33.3	16 43 45.3			17 49	1 08
Itanagar	16 40 35.0	16 43 47.1			17 54	1 13
Jaipur	16 40 44.6	16 43 56.2			19 05	2 24
Jalandhar	16 40 47.8	16 43 59.4			19 13	2 32
Jammu	16 40 49.2	16 44 00.9			19 19	2 38
Kanyakumari	16 40 37.4	16 43 48.9			18 31	1 50
Kavalur	16 40 36.7	16 43 48.2			18 31	1 50
Kavaratti	16 40 41.8	16 43 53.2			18 53	2 12
Kohima	16 40 33.7	16 43 45.8			17 49	1 08
Kolkata	16 40 34.2	16 43 46.0			18 07	1 26
Kozikode	16 40 39.2	16 43 50.7			18 42	2 01
Lucknow	16 40 40.8	16 43 52.6			18 44	2 03

“** **” indicates the event occurs after sunset.

LOCAL CIRCUMSTANCES RELATING TO CERTAIN PLACES IN INDIA

Place	Ingress Exterior contact	Ingress Interior contact	Egress Interior contact	Egress Exterior contact	Sunset	Duration
	h m s	h m s			h m	h m
Madurai	16 40 36.9	16 43 48.4			18 30	1 49
Mangalore	16 40 40.3	16 43 51.7			18 48	2 07
Mount Abu	16 40 46.0	16 43 57.6			19 14	2 33
Mumbai	16 40 43.6	16 43 55.1			19 05	2 24
Murshidabad	16 40 35.1	16 43 47.0			18 10	1 29
Muzaffarpur	16 40 37.7	16 43 49.6			18 25	1 44
Mysore	16 40 38.6	16 43 50.0			18 40	1 59
Nagpur	16 40 39.1	16 43 50.7			18 42	2 01
Nasik	16 40 43.2	16 43 54.7			19 03	2 22
Panaji	16 40 41.5	16 43 53.0			18 55	2 14
Patna	16 40 37.4	16 43 49.3			18 24	1 43
Pondicherry	16 40 36.0	16 43 47.5			18 27	1 46
Port Blair	16 40 28.7	16 43 40.6			17 35	0 54
Pune	16 40 42.6	16 43 54.1			19 00	2 19
Puri	16 40 34.2	16 43 46.0			18 14	1 33
Raipur	16 40 37.4	16 43 49.2			18 33	1 52
Rajkot	16 40 46.9	16 43 58.3			19 18	2 37
Ranchi	16 40 36.1	16 43 48.0			18 20	1 39
Shillong	16 40 34.5	16 43 46.5			17 59	1 18
Shimla	16 40 46.2	16 43 58.0			19 06	2 25
Silchar	16 40 33.6	16 43 45.7			17 54	1 13
Siliguri	16 40 36.5	16 43 48.4			18 13	1 32
Silvassa	16 40 43.7	16 43 55.2			19 05	2 24
Srinagar	16 40 50.4	16 44 02.1			19 22	2 41
Sringeri	16 40 39.7	16 43 51.2			18 46	2 05
Tamelong	16 40 33.6	16 43 45.7			17 50	1 09
Thanjavur	16 40 36.2	16 43 47.7			18 27	1 46
Thiruvanantapuram	16 40 38.1	16 43 49.5			18 34	1 53
Udaipur	16 40 45.1	16 43 56.7			19 10	2 29
Ujjain	16 40 42.8	16 43 54.4			18 59	2 18
Vadodara	16 40 44.4	16 43 55.9			19 07	2 26
Varanasi	16 40 38.5	16 43 50.3			18 32	1 51

“** **” indicates the event occurs after sunset

The last transit of Mercury occurred on 6 November, 2006 when just end of the event was visible from the extreme north eastern parts of India at the time of

sunrise. The next transit of Mercury will take place on 11 November, 2019 but the event will not be seen from India as the same will begin after the sunset

time of all places in India. The transit of Mercury on 13 November, 2032 will be visible again from India.

The apparent diameter of Mercury will be nearly 12 arc-second which is 1/158 of Sun’s apparent diameter. Thus, it will be difficult to see the Mercury at

transit over the face of the Sun without optical magnification. This event can be viewed with the help of binocular or telescope attached with proper solar

filter or by making projection of the Sun’s image on a white board by telescope. The Sun should never be viewed with the naked eye. Safe technique to

observe is by using filter like aluminized mylar, black polymer or welding glass of shade number 14.

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