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| An artist's concept of what Kepler-1649c could look like from its surface. Credit: NASA/Ames Research Center/Daniel Rutter |
NASA announced the retirement of the Kepler telescope on 30 October 2018, after a mission lasting more than nine years. During its mission Kepler found more than 2,900 exoplanets through transit method. The huge data from Kepler will keep scientist and astronomers busy for many years, which involves - reanalyzing, double checking the previously found exoplanets, etc.
While reanalyzing the old data from the Kepler telescope, a group of scientists found a new exoplanet 300 light years from Earth - Kepler 1649c. While the previous searches using a computer algorithm missed this new world, while reanalyzing the data scientists observed the periodic dips in the luminosity of the star and indeed confirmed, it is a planet. However, what makes this newly discovered world interesting is, out of all the exoplanets discovered by kepler telescope this planet is the most similar to Earth in terms of size and temperature!!
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| A comparison of Earth and Kepler-1649c, an exoplanet only 1.06 times Earth's radius. Credits: NASA/Ames Research Center/Daniel Rutter |
Kepler 1649c is about 1.06 times the size of Earth and at the same time, the starlight it receives is 75% the amount we receive from Sun. This indicate that the temperature of the planet can be similar to that of Earth.
There are other planets similar to Earth in terms of size like - TRAPPIST-1f, while some may be similar to us in terms of temperature like TRAPPIST-1d or TOI 700d. But none are this similar to Earth in terms of both size and temperature.
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| An illustration of Kepler-1649c orbiting around its host red dwarf star. This newly discovered exoplanet is in its star’s habitable zone and is the closest to Earth in size and temperature found yet in Kepler's data. Credits: NASA/Ames Research Center/Daniel Rutter |
Kepler 1649c orbits a red dwarf star, completing one revolution in just 19.5 Earth days. The red dwarf star are the most common type of star in the milky way galaxy. Though red dwarf star are known for solar flares - which can rip off any existing atmosphere of a planet - as of 2020, scientists have not observed any solar flares emitted by the host star.
Even though Kepler 1649c is a lot similar to Earth, a very little is known about its atmosphere. Atmosphere plays an very important role in surface temperature and any prospect of alien life. The thickness and composition of the planet's atmosphere is yet to be determined though it is predicted to be similar to Earth's.
There is one more planet in the system, Kepler 1649b, orbiting the star at nearly half the distance as Kepler 1649c, similar as Venus orbits Sun at nearly half the distance than Earth. However, a striking feature of the planetary system is the nine to four resonance of the two planets i.e. every nine times Kepler 1649c orbits the host star Kepler 1649b orbits exactly four times. This indicates that the system is very stable which further increases it life potential.
Scientists think that this extra stability may come due one more planet orbiting between the two known planets. However, we haven't found any sign of the speculated world. This may be due to its very small size or highly inclined orbit.
Missions like Kelpler and TESS help in the advancement in astrobiology and research in how environmental conditions and other variables can effect the potential of a world to harbor life as we know it.
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