Astronomers from Japan’s Goddard Space Flight Center and Osaka University have released a study that describes the first known rogue planets and predicts the discovery of at least 400 more worlds soon.
As Phys.org explains, rogue worlds are worlds that literally float in space without reference to any stars. In recent years, researchers are increasingly inclined to believe that there may be many more such worlds than there are planets orbiting their stars.
A major breakthrough in their research, as astronomers predict, may come after the launch of the Nancy Grace Roman Space Telescope mission. Its launch is scheduled for May 2027. It will specialize in finding rogue planets. As the authors of the article write, this telescope is already capable of discovering in the foreseeable future at least 400 rogue worlds with the mass of the Earth.
Scientists can tell from the results of two studies that established the existence of the first two known rogue planets. The findings of the international team are based on a nine-year study called MOA – Microlensing Observations. They were carried out at the Mount John University Observatory in New Zealand.
As the scientists explain, anything with mass distorts the fabric of space-time, including light from distant stars. This light is forced to bend around objects as it passes close to them. Such objects act as a natural lens. They create a brief burst of light from the background star that gives astronomers clues about themselves. Science has no other way to obtain such information yet.
“Microlensing is the only way to find objects like free-floating, low-mass planets and even primordial black holes,” says lead author Takahiro Sumi, a professor at Osaka University. “It’s very interesting to use gravity to detect objects we never expected to see directly.”
Using this method, the team has already discovered a rogue planet with a mass comparable to Earth. An article describing the find will appear in an upcoming issue of The Astronomical Journal. He will also publish the second article, which presents an analysis of such worlds in general. The announcement suggests that there could be around six times as many rogue planets as there are worlds orbiting their stars in our galaxy.
By the way, in recent decades more than 5,300 planets have been discovered outside our solar system. The vast majority of them are huge, compared to Earth, worlds or planets located very close to their stars. These objects are a priori unsuitable for life as we know it. On the contrary, recent research suggests that rogue planets tend to have Earth-like characteristics.
“We found that Earth-sized rogue planets are more common than more massive worlds,” Sumi says. “The difference in average mass between star-bound planets and free-floating planets is key to understanding their formation mechanisms.”
