This world must be smaller than the Earth and travels through the Milky Way without orbiting any stars. Its mass is between Earth and Mars.
Astronomers have discovered a small exoplanet roaming the Milky Way, without orbiting any stars. This appears to be one of the smallest planets discovered, with dimensions smaller than Earth. Its mass is between the values of Earth and Mars, advances Space.com, being a type of planet that scientists call “rogue planet”.
Scientists at the University of Warsaw, Poland, explain that their discovery demonstrates that it is possible to detect freely floating planets of lower mass through the observation of telescopes on Earth. And when confirmed, this discovery can be a big step in the study of this family of planets, which are believed to be abundant in the galaxy, but very difficult to be detected.
So far, astronomers have discovered more than 4,000 exoplanets, which have already been confirmed. Most of them were detected by their brightness when they move and cross with their star from the observation point. But with the Rogue Planets, that doesn’t happen due to the lack of a star.
This planet, observed by the Las Campanas Observatory, in Chile, was detected using a technique called gravitational microlensing. As explained, this method of “hunting the planet” involves the observation of objects in the foreground passing in front of distant stars, which serve as a background. When this happens, the nearest body acts as a gravitational lens, increasing the star’s light to reveal the mass of these objects, among other characteristics.
The chances of observing microlensing events are very slim, because the three objects: light source, lens, and observer must be perfectly aligned, says Przemek Mroz, a researcher at the California Institute of Technology, author of the study. “If we look at just one star as a source, we would have to wait nearly a million years to see that source being used as a microlens.” Now it remains to be confirmed whether this planet is really “independent” in future studies.
Astronomers consider that most of these planets are born in a “normal” way, through gas and dust revolving around a newly formed star. But these worlds are eventually stripped of their native systems through gravitational interactions with other bodies, especially with their gas giant brothers. The theory is that most of these rogue planets ejected in this way are rocky worlds with masses between 30% and 100% of the Earth, according to Przemek Mroz.
NASA is preparing to launch the Nancy Grace Roman space telescope, built for observation using microlenses, and catalog about 250 rogue planets, including some 60 that have an Earth-like or lighter mass.