Astronomy-enthusiasts are in for a rare treat today as the Mercury journeying across the Sun will be clearly observable from the Earth today.

A transit is when a planet or a satellite passes between the Sun and the Earth. The occurrence of Mercury passing through between the Earth and the Sun happens only a handful of times in a century.

The last transit of Mercury took place on May 9, 2016, and the next transit will take place, not before 2032.

Areas that will be able to view the 2019 transit include the Americas, the Atlantic, Pacific Oceans, New Zealand, Europe, Africa, and western Asia.

These areas can observe the 2019 transit from around 06:35 CST (Central Standard Time, which is the standard time followed by North America) which translates to around 18:05 in the Indian Standard Time.

The Mercury transit is expected to last almost six hours, with the closest distance of Mercury to the Sun to take place around 09:20 CST (20:50 in Indian Standard Time).

Only areas that will have the Sun visible during the given time will be able to view the transit.

How does the transit appear to us?

A powerful telescope, one that has a magnification of at least 50x, will show a tiny black dot (Mercury) gliding across the Sun. Mercury covers only 1/283 part of the Sun’s apparent diameter, so it will not be visible to the naked eye.

On that note, it is advisable to use proper eye protection while viewing the transit lest it might damage your eyes. It is never a good thing to look at the Sun directly either with the naked eye or through the telescope.

Transits help scientists to study the movement of planets and stars and even gauge the size of planets, the distance of planets from their stars, and much more.

Viewing transits and eclipses provide opportunities to engage the public, to encourage one and all to experience the wonders of the universe and to appreciate how precisely science and mathematics can predict celestial events – Mitzi Adams, a solar scientist in the Heliophysics and Planetary Science Branch at NASA’s Marshall Space Flight Center in Alabama

Edmund Halley, who used a transit of Venus in 1761 and 1769 to determine the absolute distance to the Sun, had also recorded the transit of Mercury across the Sun in the 17th century.