The planet appears to be very similar to ours in several ways.

Researchers have again found a special exoplanet hidden in old Kepler data. It is an earth-like planet that has been baptized Kepler-1649c. A special find. Because of all the exoplanets that the now retired space telescope has surfaced – there are about 2600 – Kepler-1649c appears to resemble our Earth the most in terms of size and estimated temperature.

Kepler-1649c
The newly discovered exoplanet has a rocky composition and is located about 300 light-years from Earth. Kepler-1649c orbits in the habitable zone around its parent star – a red dwarf – meaning that there may be liquid water on the planet’s surface. The planet is so close to its parent star that a year on Kepler-1649c equals just 19.5 Earth days. In addition, Kepler-1649c is only 1.06 times larger than our own planet and receives about 75 percent of the amount of starlight Earth receives from the sun. This means that the temperature of the exoplanet may also be similar to that of Earth.

More on red dwarf stars
Red dwarf stars (M stars) are the most abundant and longest living stars in the universe. They are a bit smaller and cooler than our own sun. In the search for viable planets, researchers had long aimed their arrows at red dwarf stars. That’s because they often harbor rocky planets. And some of these Earth-like worlds also rotate in the habitable zone. All these ingredients together make red dwarfs very interesting in the search for extraterrestrial life. Recently, however, there has been a shift towards orange dwarf stars (K stars). That’s because planets orbiting red dwarfs are often bombarded with dangerous ones X-ray and ultraviolet (UV) radiation, which can be up to hundreds of thousands of times more intense than what the earth receives from the sun. Orbiting exoplanets are therefore unsure of their lives and can be robbed of their atmosphere at any time. It means that these planets are possible be bone dry. Although of course there can always be exceptions …–

All in all, Kepler-1649c seems to have quite a few similarities with our own planet. “This intriguing, distant world gives us even more hope that a second Earth is waiting to be discovered among the stars,” said researcher Thomas Zurbuchen. Although we should not cheer too early. A lot is still unknown about the newly discovered exoplanet. We do not yet know anything about its possible atmosphere, which influences the temperature of the planet. Still, Kepler-1649c is of great interest to scientists who hunt planets with potentially habitable conditions. Because although other exoplanets have been found about the size of the Earth – such as TRAPPIST-1f and possibly Teegarden c – and we also know that some exoplanets have a similar temperature to Earth – think TRAPPIST-1d and TOI 700d – an exoplanet has never been found that resembles Earth in size and temperature. And add to that that Kepler-1649c is also in the livable zone.

A comparison between the Earth and Kepler-1649c. Image: NASA / Ames Research Center / Daniel Rutter

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Discovery
The researchers discovered the special exoplanet by manually digging through old Kepler data. This shows once again that not everything can be automated just like that. Earlier, scientists developed a special algorithm called Robovetter to get through the enormous bulk of data collected by space telescope Kepler. And that in itself is quite handy. Namely, Kepler searched for planets using the transit method, which means that he stared at stars for years in hopes of seeing a star’s brightness decrease periodically. Such a regular decrease in brightness may indicate that a planet orbits around that star that occasionally stands between Kepler and the star and blocks some of the starlight. Usually these dips are caused by phenomena other than planets. Think of natural changes in the brightness of a star or other cosmic objects rushing by. It is then Robovetter’s job to uncover those dips that may be caused by planets.

False positive
However, false positive results often roll out here. This means that Robovetter incorrectly attributes certain dips to sources other than planets. And so the researchers knew that these data had to be double checked. The team reviewed and reviewed all false positive results. And between these dates they discovered the special exoplanet Kepler-1649c. Although scientists are working to further automate analysis processes, this discovery demonstrates the value of a manual, double check. “If we hadn’t checked the work of the algorithm, we would have missed it,” said researcher Andrew Vanderburg.

The system appears to harbor another rocky planet of about the same size. It orbits the red dwarf about half the distance as Kepler-1649c. The team also looked for evidence of a possible third planet, but unfortunately without results. The findings point out that there may be promising Earth-like planets orbiting red dwarf stars; a type of star that is increasingly being written off for this. “The more data we collect, the more evidence we find that potentially habitable Earth-size exoplanets often occur around this type of star,” says Vanderburg. “Red dwarfs are almost everywhere in our galaxy. And with these small, possibly livable and rocky planets around it, the chance that one of them is not very different from our Earth is quite present. ”