The Transit of Venus this week launched an invasion of alien bugs from the planet to the Earth, a leading but controversial astrobiologist has claimed. Professor Chandra Wickramasinghe believes that thousands of billions of bacteria and viruses were carried from Venus into our own atmosphere following the event. He says they will eventually fall to the surface inside raindrops. 

An impression of how the solar wind strips air from Venus. Credit: ESA

The transit occurred when Venus passed directly between the Earth and the Sun and so was seen to cross the solar disk as a dark spot. At that time, the professor believes, a cosmic breeze called the solar wind stripped living bugs from the Venus’s upper atmosphere and carried them to us.

Venus is a twin planet to Earth in terms of size and it too has a rocky surface. But beneath its permanent clouds the pressure of the sulphuric air is crushing and the surface is twice as hot as inside a domestic oven.

Despite this, many scientists have long speculated that there could be life on Venus in the form of simple microbes in its cooler cloudtops, similar to lifeforms found in our own upper atmosphere.

Professor Wickramasinghe estimates that a gram of biological material from Venus would have reached Earth following the transit on Wednesday. And he says such injections of Venusian microbes must have happened many times before in the long history of evolution of life on Earth.

Professor Wickramasinghe, of the University of Buckingham’s Centre for Astrobiology, said: “The Venus transit on June 2012 offered the best chance in perhaps a century for the direct transfer of microorganisms from the clouds of Venus to Earth.

“While conditions near the surface of Venus, greater than 460°C, rule out microbial life, the temperature and pressure regime prevailing 70–45 km in altitude defines a “habitable zone” in the atmosphere for some types of extremophilic bacteria that are actually found on the Earth.

“Water, albeit in small quantities, has been identified in the atmosphere, adequate for microorganisms to concentrate and exploit.”

He adds, in a paper for the somewhat unorthodox Journal of Cosmology: “The lining up of the Sun, Venus and Earth and the relative proximity of Venus to Earth offers an easy route for microbes. provided suitable mechanisms exist for lofting cloud particles to high enough altitudes in the atmosphere for them to become entrapped in the solar wind.”

He adds: “Charged bacteria and viruses entering the Earth’s magnetosphere would initially follow magnetic field lines, and their quickest and most direct descent will be near the poles. At other latitudes descent to ground level will depend on the particle size as well as the prevailing meteorological factors and could take from days to months.

“Venusian microbes will eventually be included as nuclei of rain drops and mist and be added to the Earth’s biosphere. If they are able to replicate in the Earth’s biosphere, they would certainly have contributed modestly to our planet’s genetic heritage.

“Venus – the goddess of love – may then be said to have impregnated Earth with alien genes, as indeed she would have being doing for countless ages in the past.”

Professor Wickramasinghe, 72, is famous for his controversial ideas that viruses including those causing flu epidemics, and even life itself, were brought to Earth by comets.

In April he claimed that egg-like structures found inside a meteorite from Mars that landed in Morocco last year offered proof that life had existed on the Red Planet.