NASA’s Kepler Space Telescope caught a glimpse of four “free-floating” planets in deep space that appeared to be wandering all alone unbounded to any star.

The study was led by Iain McDonald from the University of Manchester in the United Kingdom (now at the Open University in the U.K.), employed data collected in 2016 during NASA’s Kepler Space Telescope’s K2 mission phase, according to the Daily Mail.

Kepler kept close track on a crowded field of millions of stars near the core of our Galaxy every 30 minutes during this two-month study in order to discover uncommon gravitational microlensing events. 

“These signals are extremely difficult to find. Our observations pointed to an elderly, ailing telescope with blurred vision at once the most densely crowded parts of the sky, where there are already thousands of bright stars that vary in brightness, and thousands of asteroids that skim across our field,” Professor Iain McDonald, author of the study.

Amid the 27 possible microlensing signals with short durations ranging from an hour to ten days, the study team identified four new planets that they believe to be “of similar masses to Earth.”

“It’s about as easy as looking for the single blink of a firefly in the middle of a motorway, using only a handheld phone,” said Professor McDonald of the chance for them to be able to catch sight of the existence of the planets.  

The researchers suggested that the planets could have been ejected away from their original host star in a tussle with their heavier planetary siblings in the system.

Although the researchers have not been able to detect the planets’ specific location, Professor McDonald projected they could be “several thousand light-years away.”

Despite being ejected from their solar systems, earlier research has revealed that rogue planets may be able to retain over half of their moons during the ejection process, allowing them to maintain life-like conditions for billions of years.

“If a planet like the Earth was flung out into deep space, far from the heat of a star, we’d expect the oceans to freeze over and the atmosphere to condense out onto the surface,” said the professor. “Life could still continue, but only in places like hydrothermal vents, where there is another energy source.”

NASA’s Kepler telescope was launched in 2009 with an initial mission to look for Earth-size planets orbiting other stars, but it was decommissioned in 2018 after running out of necessary fuel.

Kepler resumed its mission with the K2 project with the remaining fuel and would change its field of view to new portions of the sky about every three months to collect data. 

“Kepler has achieved what it was never designed to do, in providing further tentative evidence for the existence of a population of Earth-mass, free-floating planets,” said study author Eamonn Kerins at the University of Manchester.

“Now it passes the baton on to Roman that will be designed to find such signals, signals so elusive that Einstein himself thought that they were unlikely ever to be observed,” he added.