Despite cloudy skies, the rare event was seen by lucky watchers in Tsim Sha Tsui A handful of lucky amateur astronomers in Tsim Sha Tsui yesterday managed to peer through the clouds to witness a rare celestial happening - the first movement of Mercury across the face of the sun this century. The phenomenon occurs when Mercury comes between the Earth and the sun. During the transit, Mercury, one of the smallest planets in our solar system, can be observed as a small black dot moving across the face of the sun. The Hong Kong Observatory said areas facing west such as Pokfulam, Stanley, Lamma Island, Cheung Chau and Tai O offered the best view, but the Sky Observers' Association said a few of its members saw the phenomenon from outside the Cultural Centre in Tsim Sha Tsui. 'Some of our members saw it periodically when the sky cleared a bit in the afternoon,' association president Wong Hin-fan said. 'We were lucky. We didn't think the weather would allow us to see it.' Yesterday's transit lasted more than five hours, from 1.12pm to 6.29pm. The observatory's scientific officer, Chan Ying-wa, said cloudy skies prevented most people in Hong Kong from observing the phenomenon. 'It's too cloudy. I doubt if people could see it from Hong Kong,' he said. 'Even if you do manage to see it, it would be a small black dot moving across the sun's disc, so unless you know what you are looking at, you might not even spot it. It's not as dramatic as an eclipse.' Mercury's transits occur in early May or November and there are about 12 such transits each century. Hong Kong will be able to observe nine transits this century, including yesterday's. The next transit observable from Hong Kong will be on November 9, 2006. The last one seen from Hong Kong was on November 6, 1993. Because sunlight can damage the eye, observers must not look directly at the sun or through a telescope, and should avoid observing the transit for a prolonged period. One safe way to watch the transit phenomenon is to project the sun's image on to a piece of white paper or cardboard and view the reflection. There will be four eclipses this year, two of the sun and two of the moon. However, only one will be visible from Hong Kong: a total eclipse of the moon on November 9.