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RandomFactor [soylentnews.org] writes:

Astronomers have used microlensing to detect an approximately Earth-mass planet wandering between the stars. [universetoday.com]

Finding something in deep space that emits no light of its own is extremely challenging. But two organizations are doing just that. They're the OGLE [astrouw.edu.pl] (Optical Gravitational Lensing Experiment) collaboration and the KMTN [kasi.re.kr] (Korean Microlensing Telescope Network) collaboration.

Now, a team of scientists from both groups have announced the discovery of a low-mass rogue planet. There are no stars near it, and its distance from Earth is unconfirmed.

The team says it proves that the microlensing technique is effective at finding Earth-mass planets that are free-floating in space.

The paper announcing the discovery [arxiv.org] has 30 authors.

A relatively tiny object like a low-mass planet doesn’t bend much light, and not for too long, either. In their paper the authors say “Microlensing events due to terrestrial-mass rogue planets are expected to have extremely small angular Einstein radii [wikipedia.org] (.1 µas) and extremely short timescales (0.1 day).” According to the authors, this is the “most extreme short-timescale microlens discovered to date.”

Estimates for the number of rogue planets wandering our galaxy range between "a few billion and a trillion [universetoday.com]."

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