“Transit of Mercury”. You have a very good opportunity to see the transit of Mercury on 9th May 2016. A small black dot of mercury will pass slowly from sun’s white colored disk (color of sun can vary by changing the type of solar filter) in East-to-West direction. Transit will start at 11:12 GMT and ends at 18:42 GMT on same day of 9th April and hence total transit period is 7 hours and 30 minutes. The planet will cross the Sun in direction North-East to South-West. Last Mercury Transit seen from Earth was on 8th Nov 2016 and direction of that was from South-East to North-West. This is because May and November transits of Mercury are viewed from opposite sides of the Earth’s orbit.
The German astronomer Johannes Kepler (1571-1630) was first who predicted Mercury transit event, although he could not observe one himself. His predicted date of a transit was November 7th 1631.
Mercury and Venus can make solar transit as these planets lies between Earth and Sun. Recent transits of Venus occurred on 8 June 2004 and 6 June 2012. If you have missed these, you will not be able to see it again in your life. Next generation may be, as next Venus transit will be on Dec 2117. Even if we count from today, 101 years have to go for next transit, so this will hopeless. But Mercury transit can be seen by us in this month. Mercury transit is not much rare event as compared with Venus. In 21st century, there are only 2 Venus transits while 14 mercury transits.
Mercury appears much smaller than Venus and you need optical aid to see this event. During this Mercury transit, apparent diameter of Sun will be 1900 arc seconds while only 12 arc seconds of that mercury’s diameter. It means, mercury will look 158 times smaller than Sun.
As Mercury is visible against the solar disk, a transit can be viewed from anywhere on the Earth wherever the Sun is above the horizon at the time of the event. The whole transit will be visible from most of Earth including the Western Europe, extreme North-West Africa, Eastern North America, Northern South America, Greenland and the Arctic.
The transit begins before sunrise for observers in western North America. The transit ends after sunset for Eastern Europe, Asia and most of Africa. Regions where the entire transit is visible include eastern North and South America, the Atlantic Ocean, and Western Europe.
The transit will be end after sunrise for observers in Eastern Europe, Western Asia and most of Africa. None of the transit will be visible from Australia, extreme Eastern Russia and China, Japan, the Korean peninsula, the Philippines, Eastern Malaysia, Indonesia and most of Antarctica because the Sun is below the horizon from these locations.
Mercury’s ingress (start of transit) will be at 11:12:19 GMT while greatest transit (midpoint) will be at 14:57:26 GMT. Egress (end of transit) will be at 18:42:26 GMT.
While transit occurring, Venus and Mercury, both are subject to Black Drop Effect, a mysterious phenomena. It occurs just after the second contact and again just before the third contact. It was first observed during a transit of Venus in 1761. This phenomenon effectively present with Venus transit and to smaller extent during Mercury transit. A small black “teardrop” appears to connect planet’s disk to the limb of the Sun. This effect was long thought to be due to Venus’ thick atmosphere and first evidence that Venus had an atmosphere. And now it is thought by many to be an optical effect caused by the smearing of the image by turbulence in the Earth’s atmosphere.
Observing precautions:
During transit, Extreme Caution Must Be Taken When Attempting To Observe This Event. The safest way to observe this event, is to project the image of the Sun through a refracting telescope on white paper. Binoculars can similarly be used projection.
You can use solar filters also. There are various types of solar filter are available in market. You can attach an aluminized Mylar solar filter to the front of the telescope for observation. Aluminized solar filter may appear in white, pale blue or pale yellow depending upon the manufacturer’s design.
Don’t Miss this opportunity as next Mercury Transit will be on 11 Nov 2019 and then 13 Nov 2032.
Some Useful Links:
http://eclipsewise.com/oh/tm2016.html
https://www.fourmilab.ch/documents/canon_transits/
http://eclipse.gsfc.nasa.gov/transit/catalog/MercuryCatalog.html