Missing Mass = Rogue Planets?

The above image from 2011 is an artist's concept of how a Jupiter-like rogue planet might appear as it drifted through space. Image Credit: NASA/JPL-Caltech


Two studies were recently published which cast doubt on the theory that a mysterious substance known as "dark matter" is responsible for the missing material in the universe. Now, another study proposes a radical and new solution — free-floating, rogue planets.


The dark matter theory that presumably would be pushed aside by this proposal — should it prove correct — was devised to explain why about four fifths of the ma­te­ri­al in the cos­mos seems to be missing, but is apparently detectable through gravitational effects over huge distances, but is un­seen.


Through extensive calculations, many astronomers have concluded that the mis­sing ma­te­ri­al should consist of enormous clouds of some sort of particles, of­ten dubbed cold dark matter. These clouds are sup­posed to envelop and fill galaxies.


These new studies raise problems with dark matter theory. One of them found that in our section of the galaxy, dark matter simply cannot be found, whether through gravitational effects or otherwise.


The new proposal, published online May 8th in the re­search journal Astrophysics and Space Science, argues that a few hundred thou­sand billion free-float­ing, Earth-sized planets may ex­ist in our galaxy, the Milky Way, and would be among the old­est objects in our universe. What's more, some of these bodies may pass through our solar sys­tem or others from time to time, picking up a few stray bits of DNA or living cells along the way, creating new seed­ing sites for life. The new proposal is co-authored by N. Chandra Wickramasinghe and colleagues at the University of Buckingham, U.K.


This proposal supports the "panspermia" theory, popular in some circles of astronomers, hold­ing that life or seeds of it could spread through­out the cos­mos aboard asteroids or through other means. In 2008, an In­di­an scientist pro­posed that some unidentifiable red cells found in rain could have come from space, many researchers dismissed his claim, but this proposal defends it.


Support for panspermia is uneven among astronomers, but interest in searching for planets has reached a near fever pitch since 1995, when the first plan­et out­side our solar sys­tem was reported. All the 750 or so planets reported to date or­bit stars, and just a handful have been deemed potential candidates for life.


But the possibility of a much larger number of planets was first suggested in ear­li­er studies through the effects of "gravitational lensing." This effect occurs when an object's gravitational field distorts im­ages of other objects be­hind it. In this case, the objects in question are planet-sized bodies distorting the images of distant quasars, enormously bright light sources in the very distant universe.


Several groups of investigators have recently suggested that a few billion rogue planets could exist in the galaxy. The new proposal includes new calculations that increase the total to a few hundred thousand billion. It also estimates that a rogue planet might visit our inner solar system every 26 million years.


The Astrophysical Journal is a peer-reviewed scientific journal covering astronomy and astrophysics. To read more, visit the publication URL here: iopscience.iop.org/0004-637X


To learn more about exoplanets and NASA's planet-finding program, PlanetQuest, visit this URL: planetquest.jpl.nasa.gov


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