Scientists Say A Few Hundred Thousand Billion Free-Floating Life-Bearing Earth-Sized Planets Exist in Milky Way

Posted on May 11, 2012

Astrophysics and Space Science CoverScientists continue to increase the estimates of the number of planets out there in the Universe. A group of scientists now says a few hundred thousand billion free-floating life-bearing Earth-sized planets may exist in the space between stars in the Milky Way. An international team of scientists, led by Professor Chandra Wickramasinghe, Director of the Buckingham Centre for Astrobiology at the University of Buckingham, UK, is making the argument for this massive number of life supporting planets in our galaxy. The findings were published online in the journal, Astrophysics and Space Science.

The scientists say these life-bearing planets originated in the early Universe within a few million years of the Big Bang. They say these planets make up most of the so-called "missing mass" of galaxies. The scientists calculate 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.

The estimate for the number of planets in our galaxy has been on the rise since the first extrasolar planet was reported in 1995. 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 earlier studies where the effects of gravitational lensing of distant quasars by intervening planet-sized bodies were measured. Astronomers have since vastly expanded their estimates of the number of planets in the Milky Way to at least 100 billion.

Wickramasinghe and his team have now ramped up the grand total of planets to a few hundred thousand billion - a few thousand for every Milky Way star - and this count includes only lone planets, not planets orbiting a star. They have also introduced a new argument that each one of these lone planets is harboring the legacy of cosmic primordial life.