An international group of scientists led by the University of Buckingham in UK has claimed that life-bearing planets may exist in vast numbers in the space between stars in the Milky Way.
For every star in the Milky Way a few thousand dimly-lit icy planets like this could exist and be harboring microbial life (Chandra Wickramasinghe)
Their findings, published online in the journal Astrophysics and Space Science, suggest that a few hundred thousand billion free-floating life-bearing Earth-sized planets may exist in the space between stars in the Milky Way.
The researchers have proposed that these life-bearing planets originated in the early Universe within a few million years of the Big Bang, and that they make up most of the so-called missing mass of galaxies.
The group calculated that such a planetary body would cross the inner solar system every 25 million years on the average and during each transit, zodiacal dust, including a component of the solar system’s living cells, becomes implanted at its surface. The free-floating planets would then have the added property of mixing the products of local biological evolution on a galaxy-wide scale.
Since 1995, when the first extrasolar planet was reported, interest in searching for planets has reached a feverish pitch. The 750 or so detections of exoplanets are all of planets orbiting stars, and very few, if any, have been deemed potential candidates for life.
The possibility of a much larger number of planets was first suggested in previous studies where the effects of gravitational lensing of distant quasars by intervening planet-sized bodies were measured. Recently several groups of investigators have suggested that a few billion such objects could exist in the galaxy.
Prof. Chandra Wickramasinghe, a lead author and Director of the Buckingham Centre for Astrobiology at the University of Buckingham, and his colleagues increase this grand total of planets to a few hundred thousand billion – a few thousand for every Milky Way star – each one harboring the legacy of cosmic primordial life.
