Kolkata: Sky gazers in India will get a rare treat in June when the "Planet of Love" Venus keeps a lunch date with mankind after 122 years.

The rare astronomical event called "Transit of Venus" on June eight in broad daylight presents a novel opportunity for astrophysicists to see the planet move across the disc of the Sun as a pinhead-sized black dot.

Considered among the rarest of planetary alignments, only six such events have occurred since the invention of the telescope in 1631, 1639, 1761, 1769, 1874 and 1882, said the director of research and academics of the M P Birla Planetarium Dr Debiprosad Duari.

"It will be just like a solar eclipse, but instead of the Moon being in the line between Earth and Sun, it will be Venus. Not one person alive has ever seen this phenomenon," Duari said.

To be visible in Europe, parts of Africa, Middle East and most of Asia, the transit will begin at 10:44 am in Kolkata, but Venus will appear as a black dot on the face of the Sun at around 11:03 am.

The last point of contact between Venus and Sun will be at 4:50 pm.

"Only a small telescope with solar filter or a projection should be used to see the event and not directly through the naked eye," he says.

Though it falls on the official date of the onset of monsoon in India, astrophysicists are keeping their fingers crossed to keep rain clouds from playing spoilsport.

The next such event is scheduled in a not so distant future during 2012 and there after in 2117 and 2125 with the transit following a curious repeating pattern.

"The cosmic phenomenon follows a very intriguing pattern of 243 years two transits occur in December eight years apart, then a wait of 121 and a half years followed by two more transits in June again eight years apart. Another wait of 105 and half years and the cycle repeats itself," Duari explains.

While Jerimiah Horrocks and William Crabtree were the first to witness a transit of Venus in 1639, none of the present day astrophysicists have seen on the rare treat.

The M P Birla Planetarium, Positional Atronomy Centre and a number of amateur sky watchers associations are gearing up their arsenal of binoculars and telescopes for special shows on the day of the transit.