A team of astronomers has found a lone planet the size of Earth drifting through the Milky Way. Known as a ‘rogue planet’, it is unbound to any star and, astronomers say it is likely to drift through interstellar space for an indefinite period of time.
Detecting rogue planets is no easy task. They are usually far away from light sources, such as stars, and emit no light from which to identify them. Nevertheless, two organizations are dedicated to finding them: the Optical Gravitational Lensing Experiment (OGLE) and the Korean Microlensing Telescope Network (KMTN).
A research collaboration between the organizations consisting of over 30 authors confirmed the discovery of the low-mass rogue planet- named ‘OGLE-2016-BLG-1928’. They say, however, that its distance from Earth is yet to be confirmed.
To find the planet, they used a technique known as ‘microlensing’. This technique requires two things: a distant light source, such as a star, and a closer object with enough mass to bend light from the nearest light source, much like a lens. In the case of finding rogue planets, the planet itself acts as the lens. The properties of light that reach it are able to tell astronomers about its consistency.
In this case, such low-mass planets typically don’t bend much light and do so for small fractions of time. All in all, the astronomers discovered this planet from a micro-lensing event lasing just 41.5 minutes- a small amount of time to gather detailed data. With only four other small rogues planets like this having been found previously, the authors of the study say that their finding is the most extreme short-timescale microlens discovered to date’.
Due to their wandering nature, rogue planets are extremely unlikely to be able to host life. As such, they are unlikely to receive the amount of attention or research funding that exoplanets gain. Nevertheless, studying them is still useful for understanding how nature, and the universe, work.