Next Thursday, the centre's director Salin Veerabutr said, Mercury was set to make a rare transit of the Sun, while during the night on November 17, 18 and 19, the annual Leonid meteor shower will occur.

Mercury will pass through an inferior conjunction, a point in its orbit where it is directly between the Earth and the Sun. Normally the innermost planet is not visible during an inferior conjunction.

The tiny disk of Mercury will begin moving over the Sun at 2.12am. Because it is before sunrise, stargazers would be unable to witness the initial moments. But if the sky is clear, people will be able to see the phenomenon around the end of the transit, when Mercury will move completely off the disk of the Sun at about 7.10am.

Mercury's transit will not be visible to the naked eye. A telescope must be used, with a magnification of at least 30-times, to bring out the "dark dot" of Mercury in silhouette against the Sun's disk. Care must be taken to view the event with proper filters, Salin said, and people should not look at it for longer than three minutes to avoid eye damage.

A transit is a relatively rare occurrence. As seen from Earth, only transits of Mercury and Venus are visible, however, the Mercury transit is more frequent - about 13-14 times every 100 years. It only occurs in the months of May and November.

This is the second of 14 transits of Mercury that will occur during the 21st century. The next transits are forecast for May 9, 2016, November 11, 2019 and November 13, 2032.

Another celestial feast will occur on the nights of November 17, 18 and 19 from 2am until sunrise.

The Leonid meteor shower will present a dazzling sky show with observers being able to see about 30 burning meteors an hour. However, the number will be less than the 2001 Leonid meteor shower.

"Both phenomena offer good viewing opportunities for interested people, stargazers and students to study astronomy in a real situation," said Vorawit Tanwuthi-bandit, a committee member of the Thai Astronomical Society.

Astrologer Boonlert Pairin, a former Chachoengsao senator, said the Mercury transit would create a political effect that could cause controversy during the drafting of the Constitution.