Some eyes remain fixed on the Moon, seeking revenge. Most watch Mars with great anticipation, and the rest of the Solar System also gets a good deal of attention… but there are eyes that look much further. I refer to our neighbor, the star Proxima Centauri, located a 'mere' 4.22 light-years away.
Astronomers from the ESO participating in the Pale Red Dot project have just made a spectacular announcement: there is an exoplanet in the so-called habitable zone of Proxima Centauri, which could have a mass similar to that of Earth.
It is likely that Sid Meier's phone has exploded in recent hours, not because of the imminent launch of Civilization VI, but because of the great possibility that a planet with a mass similar to Earth exists orbiting the habitable zone of Proxima Centauri. Granted: Alpha Centauri is the entire star system, and Proxima Centauri is the red dwarf that 'accompanies' the other two stars. 17 years ago, our minds played and enjoyed the idea of colonizing Alpha Centauri; however, today it is time for science fiction to step aside and give way to a group of astronomers at the ESO, who under the Pale Red Dot observation campaign have found "definitive evidence" about the existence of an exoplanet orbiting Proxima Centauri, within its habitable zone. Another interesting fact? Its mass would be only 27 percent greater than Earth's mass.
A planet in the habitable zone
A planet with a mass similar to Earth, orbiting the habitable zone of the closest star to the Solar System... how not to feel enthusiasm? Now, we must consider the rest of the details. As we mentioned above, Proxima Centauri is a red dwarf, much colder and smaller than the Sun (0.12 solar masses), therefore, Proxima b (the designation given to the new planet), must be very close to the star to occupy its habitable zone. How close is its orbit? 7 million kilometers, eight times more 'closed' than the relationship between Mercury and the Sun. Proxima b takes approximately eleven days to orbit Proxima Centauri, but its own rotation would be of a very similar period. In relaxed terms, it is like the Earth and the Moon: only one side of the planet receives the light and heat from the star, while the other remains in total darkness.
The radiation problem
Here we enter another problem, which is radiation. The temperature on Proxima b's surface could allow the existence of liquid water, but Proxima Centauri is an "ultraviolet and X-ray carnival", causing Proxima b to receive 60 times the high-energy radiation that Earth receives from the Sun, meaning its ability to retain liquid water is in doubt.
Detection and next steps
How did they manage to find Proxima b? Two words: Doppler effect. The measurements established that Proxima Centauri approached Earth at a speed of five kilometers per hour, then moved away at the same speed. The Pale Red Dot campaign allowed following the pattern for a total of sixty days, but it turned out to be so consistent that on day 30 they had already begun to prepare the publication. What happens next? More studies, more measurements, and if the budget gods help us, Starshot.
