Trillions Of “Rogue Planets” Roam Our Galaxy, Scientists Say.
The number of starless planets, or “rogue planets,” in the Milky Way may far outnumber those with stars, according to two studies to be published in the Astronomical Journal. There could be trillions of starless rogue planets drifting endlessly through space.
“We estimate that there are 20 times as many rogue planets in our galaxy as there are stars.
“This is the first measurement of the number of rogue planets in our galaxy that are sensitive to planets smaller in mass than Earth.”
The discovery is the result of a nine-year investigation that utilized a phenomenon known as microlensing to detect distant planets. In a nutshell, microlenses can distort light due to the enormous gravity of a massive object, creating a natural lens that magnifies the object behind it.
Microlenses are the only way to discover low-mass free-floating planets and primordial black holes,” explained Takahiro Sumi, an astronomer at Osaka University, in a statement.
Another interesting finding the researchers made about these wandering planets is that wandering planets tend to be smaller, while planets closer to their stars tend to be larger, or both.
They found that “Earth-sized wandering planets are more common than more massive planets. The difference in average masses between star-bound and free-floating planets holds the key to understanding the mechanisms of planet formation.”
The size difference makes sense. Smaller planets that form around a star are more likely to be bullied by the gravity of larger planets in the same system. Over time, the orbits of the planets become more dilated as the giant planets pass by, until eventually the small planet breaks away from the star and runs off.
Finding exoplanets (worlds beyond our solar system) is a daunting task. Fortunately, the Roman Space Telescope, which NASA plans to complete in 2027, will greatly advance the researchers’ work.
The Roman Space Telescope will observe from space and will be sensitive to low-mass rogue planets,” said Naoki Koshimoto, an astronomer at Osaka University and co-author of the study, in a statement. “The combination of Roman’s wide field of view and keen eyesight will allow us to study these planets in greater detail than would be possible with ground-based telescopes alone.
Based on these latest discoveries, they are optimistic that Roman will help discover about 400 Earth-sized rogue planets, and are confident that they have already found one such Earth-massive rogue planet.
Source: Trillions Of “Rogue Planets” Roam Our Galaxy, Scientists Say.
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