According to the study submitted to the Monthly Notices of the Royal Astronomical Society
and conducted by researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC)
, a joint institute of Stanford University and the SLAC National Accelerator Laboratory
, there may be 100,000 times more "nomad planets" wandering homeless in our galaxy than stars.
Scientists had thought that some of the first apparently nomadic planets detected might be orbiting stars far away, but later, they confirmed that majority have no parent star. Though scientists had long predicted the existence of nomad planets, the discovery that they actually outnumber "normal" planets and even outnumber stars was surprising and led to defining a whole new class of astronomical bodies, raising fundamental questions that may change existing theories of planet formation.
Puzzles remain, however: The characteristics of this class of planets is unknown and for all astronomers can tell they could be icy, rocky or even gas giants like the massive planets in our solar system.
According to Stanford University News
, the existence of nomad planets also raises new questions in the ongoing search for extraterrestrial life.
Lead author Louis Strigari, speculates that while nomadic planets do not have a parent star as source of heat, they could generate heat from tectonic activity
or from internal radioactive decay
. Strigari says: "If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist."
reports astronomers use a technique called microlensing
to detect nomadic planets. Physorg.com
reports that last year, researchers using gravitational microlensing technique detected about a dozen nomad planets. With this method, observers on Earth watch the effect generated when a massive body passes in front of a star. A massive body passing in front of a star, as predicted by General Relativity
, bends and magnifies the light from the star much like a lens does and makes the star light wax and wane in time. This creates a "light curve" whose characteristics indicate to scientists certain properties of the body passing in front of the star, such as its mass.
reports that conservative estimates from results obtained so far suggests there are approximately two nomadic planets for every average star in our galaxy, and what is even more astounding, and significant, in the light of the recent Planet Nibiru
apocalyptic hysteria, is that nomad planets may be as much as 50,000 times more common than initial estimates suggest.
Alan Boss of the Carnegie Institution of Science in Washington D.C., describes this staggering conclusions with flair: "To paraphrase Dorothy from 'The Wizard of Oz,' if correct, this extrapolation implies that we are not in Kansas anymore, and in fact we never were in Kansas. The universe is riddled with unseen planetary-mass objects that we are just now able to detect."
According to Stanford News
, the researchers made estimates of the "unseen planetary-mass" by calculating the known gravitation pull of the Milky Way, the amount of matter in the galaxy available for forming nomad planets and the distribution of the matter required to make formation of such planetary bodies possible. But because astronomers are uncertain exactly where these bodies come from, they are unable to come to definitive conclusions. It is believed that some of the rogue worlds might have been ejected from star systems, but according to Strigari, not all of the bodies could have been formed this way.
The researchers hope, however, that with the introduction of a new generation of telescopes, they will be able to study the nomad planets in greater detail and acquire more specific information about them. Stanford News
reports the space-based Wide-Field Infrared Survey Telescope
, and the Large Synoptic Survey Telescope
, are scheduled to begin operation in the 2020s.
Scientists are particularly excited about the potential implications of their estimates of the number of nomad planets in the Milky Way galaxy because it has significant implications for the question of the incidence of life in our galaxy. Nomad planets wandering in space may impact on other bodies, breaking out chunks of the planet and dispersing them in space. If these chunks carry microbial life nomad planets may become means for disseminating life in our galaxy. Stigari said: "If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist."
Co-author Roger Blandford, director of KIPAC
, said: "Few areas of science have excited as much popular and professional interest in recent times as the prevalence of life in the universe. What is wonderful is that we can now start to address this question quantitatively by seeking more of these erstwhile planets and asteroids wandering through interstellar space, and then speculate about hitchhiking bugs."