During our constant search of planets similar to our Earth, scientists have come across the planet known as Kepler- 438b, but recent findings have shown that radiation makes most Earth-like planets uninhabitable. This is also the case with Kepler-438b, the most Earth like planet we found so far.
This is due to the planets close relation to the red dwarf star Kepler-438, situated at a closer distance than we are to our Sun. Red dwarfs are stars are amongst the most common stars in our galaxy, or at least in the relative vicinity of our solar system.
Even if red dwarfs exist in a large number, greatly increasing the probability of earth-like planets, the habitability of planets residing in a red dwarf star solar system is still up for discussion.
Because of their relative size and gravitational pull, planets in the red dwarfs system will most likely be tidally locked in orbit around the star, half of the planet being in constant night while the other would be bombarded by radiation from said star. This greatly decreases the habitability of the planet because of the extreme temperature variations between the sides of the planet.
The problem of tidal locking with the star does not apply when looking at a moon that orbits such a planet, somehow circumventing this phenomenon by tidal locking itself to the orbit of the planet instead of the star.
In the case of Kepler-438b, radiation is the key factor when confronting its habitability and likelihood of creating life. Due to its short distance from Kepler-438, it suffers from immensely powerful solar flares, known as super flares, once every 100 days. These super flares are around 10 times greater than the largest solar flare ever recorded in our solar system, and are also known as coronal mass ejections.
The Earth-like planet could be protected from such events if it possessed a magnetic field similar to that of our Earth, but because of its lack of protection, the atmosphere surrounding the planet is peeled away, making life almost impossible to appear on Kepler-438b.
Even though Kepler-438b rated the highest on the Earth Similarity Index, it will eventually be completely stripped of its atmosphere in the future, making it uninhabitable. The probability of life appearing on a planet without atmosphere is close to zero, mainly because a planet’s atmosphere is like a shield against harmful radiation such as UV and X-ray.
This further proves how lucky we are when considering how our Earth is basically perfect for sustaining life, being at the perfect distance from a star, and also its protective magnetic shield.
Because of the recent problem that radiation makes Earth-like planets uninhabitable, the odds of finding are becoming dimmer, but taking into consideration the vastness of space, chances that another planet with a high score on the Earth Similarity Index could be found are still high.