Planet Venus, written off for any sign of life, has microbes in its atmosphere which may well be reaching earth every 580 days, a Sri Lankan scientist has claimed.

"According to the latest research, the planet Venus has a microbial ecology high in its atmosphere," Professor Chandra Wickramasinghe of Cardiff University said Wickramasinghe, a leading authority of the theory of "Panspermia" that says life on earth originated in deep space and travelled here hitch-hiking on comets, said the research was conducted by him and daughter Janaki Wickramasinghe.

Delivering the keynote address at the Annual General Meeting of the Association of Professional Sri Lankans in Britain at Baylis House in Slough, he said: "Every 580 days when the Sun, Venus and Earth are in a line, microbes from Venus can be transferred to Earth.

"The planets Venus, Earth, Mars are surely interconnected biologically and life on earth represents a connected chain of being that extends to the remotest corners of the cosmos," he said.

The second rocky planet from the sun, for a long time the bright "morning star" Venus has been talked about as a sister planet of earth and the habitat of not microbial but evolved intelligent life, some time ago.

In 1686, a French "man of letters" Bernard de Fontenelle wrote that the inhabitants of Venus resembled the Moors of Granada; a small black people, burned by the sun, full of wit and fire, always in love, writing verse, fond of music..."

But after 1960s scientists came to know the surface of the planet with lead melting heat did not resemble earth at all and was always covered with a thick layer of clouds of sulphuric acid droplets. However, the latest researches have found a different story.

In the late 1970s and early 1980s, the idea that life is a truly cosmic phenomenon was championed by the late Sir Fred Hoyle and Chandra Wickramasinghe.

These ideas were intensely controversial at the time, but over the last two decades the Hoyle-Wickramasinghe model has been vindicated by all the space missions and laboratory discoveries that have taken place.

Life is harboured in comets (there are about 100 billion comets around our planetary system) and the injection of comet-borne bacteria introduced life to Earth and to every other habitable planet, according to Wickramasinghe's theory.

He said comets brought to earth not only life but all the life-sustaining water in earth's oceans.

The Oort Cloud, at the farthest reaches of the solar system from where the spectacular comets originate indicate it consists of organic matter, he said.

Microbial life could not only travel from the farthest reaches of the universe but also from planet to planet, he said.

At the conjunction of planets, when earth, venus and sun come to one line he said one to 10 grams of bacteria is transferred from venus to earth.

This kind of transfers could be of matter consisting of primitive life but also of evolved life.