The first step in the search for extraterrestrial life is to discover planets that could potentially host them. This grand quest of finding alien life has pursued astronomers and scientists around the world to develop advance detection techniques that reliably confirms the existence of exoplanets, i.e. planets out of the solar system. Since the 1990’s, such direct and indirect detection methods have established the presence of around 3,500 of such planets. On 8th June, 2018, a group of Indian scientists expanded this list by discovering a planet located 600 light years away; enabling India to join the elite group of exoplanet discovering countries.
This historic feat was achieved by a scientific team operating out of Physical Research Laboratory (PRL), Ahmedabad – a subsidiary of Indian Space Research Organization (ISRO). The PRL team investigated reports obtained from NASA Kepler 2 photometry regarding a potential planetary source. The scientists then observed the target for 420 days, collecting information using the indigenously designed “PRL Advance Radial-velocity Abu-sky Search” (PARAS) spectrograph mounted on a 1.2m telescope in Mount Abu, India. A spectrograph precisely measures the radial velocity of the spectral shift caused due to the gravitational pull exerted by a planet on its host star. The radial velocity measurements are then used to indirectly infer the mass of the pertinent planet. PARAS, the first of its kind in India, found the mass of the exoplanet to be 27 times that of earth; thus joining a handful of other spectrographs around the world (USA and Europe) that have successfully used radial velocity measurements to conform the existence of a planet.
Orbiting around the host star EPIC 211945201 or K2-236, the planet was accordingly named as EPIC 211945201b or K2-236b. The planet is 6 times larger than earth, classifying as super-Neptune or sub-Saturn in its size. Despite its relatively enormous volume, the planet lies 7 times closer to its parent star than the distance between the sun and earth; thus taking just 20 days for a complete revolution. Model based calculations suggest that 60-70% of its total mass comprises of ice and heavily elements like silicates and iron. Moreover, the PRL team takes pride in the fact that only less than 1% of discovered exoplanets have such precise measurements of weight and size.
With surface temperature reaching 600°C, K2-236b most definitely lies out of the “goldilocks zone” – the habitable range of distance from a parent star at which liquid water can exist on the surface. The discovery of a planet that lies in this zone significantly bolsters their chance of being able to host life-forms. Out of the 3,730 exoplanets discovered so far, only 53 have been found to lie in the goldilocks zone – deeming them “potentially habitable”. Nonetheless, the discovery of K2-236b is extremely vital as it can help scientists understand the mechanism by which large planets form so close to their parent star.
With a recent string of groundbreaking feats, India has established their formidable presence in space research and technology. In 2014, India successfully launched its first Mars Orbital Mission, Mangalyaan, at first attempt. This mission received universal accolades for being considerably cheap than western counterparts. With the discovery of K2-236b, ISRO announced its plan to launch PARAS-2 and upgrade the telescope atop Mt. Abu to 2.5 m by 2020. For India’s hungry cesspool of talented scientists, such indigenous advancement will not just fuel the quest to find extraterrestrial life but also might help answer questions about the origin of the universe.