On 24th August 2016, Mikko Tuomi, a Finnish Astronomer made a Discovery of an exoplanet, Proxima Centauri B. The planet was first discovered through an old spectrograph instrument-HARPS on the ESO’s 3.6-meter telescope. HARPS, standing for High Accuracy Radial Velocity Planet Searcher was used to find planets that orbited other stars, with an average resolution of R=120,000. (1) Dr. Guillem Anglada-Escude, a Catalan Astronomer conducted further research on the exoplanet discovered by his colleague, leading to Proxima B’s discovery confirmation in 2020 after 63 spectroscopic observations of the exoplanet were acquired in 2019 through a newer spectrograph, ESPRESSO. (2-3) Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observations(ESPRESSO), an ultra-stable fiber-red high-resolution instrument is used in ESO’s Very Large Telescope(VLT) to conduct exo-planets research with higher accuracy and precision. Its resolution ranges from R=140,000, 120,000 or 70,000. (4)

The finding of Proxima B only occurred much later despite its closest location to Earth and its orbiting star, Proxima Centauri being found for longer than a century. Proxima Centauri was discovered in 1915 by Scottish astronomer Robert Innes in Johannesburg, South Africa. (5) Proxima B is impossible to spot with an unaided eye due to its relatively small planet size and its mother star’s ( Proxima Centauri ) small dimensions and dimness that radiates less light from the sun. (6) Proxima Centauri is 12% of the sun’s mass and only radiates 0.02% of sunlight which is an infra-red range that one cannot see, thus contributing to its elusiveness. Hence, Proxima B was only found recently as much effort and technology advancement was required. (7) Proxima B orbits an M-type star (red dwarf) and is only 4.2 light years away from Earth, making it the closest exoplanet ever discovered. ( Light year refers to a unit of astronomical distance equivalent to the distance light travels in a year, approximately 9.4607 x 10^12 km or 6 million million miles ). The planet also exhibits characteristics alike Earth, such as its mass which is 1.27 times Earth’s. Moreover, it takes 11.2 days to orbit its star and is
within Proxima Centauri’s habitable zone. (8)

The discovery was considered a Eureka moment to astronomers and the human species as it enhanced the studies of planets orbiting red dwarf stars as well as signifies that it could host lives and serve as a potential habitable planet for humans to thrive in the future. As Earth’s closest neighbor planet that orbits an M-type star, it provided an exceptional opportunity to understand the adaptation and characteristics of a terrestrial planet which would be most beneficial as M dwarfs are the most common stars that comprise 70% of stars in the galaxy. This opens endless doors to the studies
of many more exoplanets. (9)

To be considered a terrestrial(Earth-like)planet, it has to be of a similar size, orbit its star habitable zone, and have a rocky surface. As Proxima B is within the habitable zone of its star, scientists believe that the planet may become one that continues the existence of the human species. The habitable zone of a red dwarf - 0.04 to 0.1 AU, distance from Proxima B to the star-0.05 AU. (10) Furthermore, due to the planet’s denseness(mass similar to Earth), the dry version of the planet may possess rocky surfaces. Since Proxima B has met the majority of the criteria, it is listed as one of
the most Earth-like planets.

However, being terrestrial does not guarantee the habitability of the planet. Criteria of a habitable planet include factors, such as the presence of liquid, suitable atmosphere, and orbital properties. The National Center for Scientific Research used simulations to predict the water composition of the planet and suggested that the planet would be surrounded by a rocky mantle and an ocean 200km deep occupying 0.05% of its mass. (11) Nevertheless, Proxima B encounters ultraviolet radiation from the sun 200 more times than Earth. This may lead to a temperature that is too high to maintain an Earth-like atmosphere and may strip away essential elements like oxygen over time. (12-14) Even though its habitability has yet to be confirmed and more advanced research is required on Proxima B, it remains as one Eureka discovery with its benefits to the study of planets orbiting red dwarfs and its many possibilities of being habitable that increases the likelihood for humans surviving and thriving on other planets.