An exoplanet is a planet outside the Solar System that orbits another star . They are also called extrasolar planets and are characterized by revolving around a star that has enough mass to be spherical and is in a more mature stage, that is, free of the dense gas disk that surrounds new stars.
The word exoplanet derives from the Greek, and is made up of the prefix exo -, which means ‘outside’, and planétes which refers to ‘something wandering’.
The discovery of exoplanets is important, as it helps to expand the knowledge about the theories and models of galaxy and star formation.
Our Solar System that revolves around our star, the Sun, is 4.6 billion years old. The discovery of younger or more mature systems with exoplanets orbiting other stars would help determine the nature of the Solar System and the habitability of other planets.
See also:
- Star.
- Planet.
Discovered exoplanets
More than 5,000 exoplanets have been discovered to date with ground-based telescopes such as ESO’s HARPS, and space telescopes such as NASA’s Kepler and CNES’s COROT in conjunction with ESA.
Among the discovered exoplanets, 2,950 of them have been confirmed as such by detection tools and 2,504 are awaiting confirmation.
In 2017, the discovery by ESO and NASA of seven Earth-size planets orbiting the TRAPPIST-1 system , a small red star the size of Jupiter, located in the constellation Aquarius 40 light-years from Earth, is already significant. that there are three planets that meet the ideal characteristics for the development of carbon-based life: ideal size and located within the range of habitability.
Habitable exoplanets
The astrobiology or exobiology , known as the study of the possibility of life beyond Earth, has defined the following two main features for the development of carbon – based life:
- The planet or exoplanet must be of adequate size: this means that it must be large enough (between 1 to 10 Earth masses) so that it can retain the atmosphere but, in turn, not so massive that it does not retain only gases such as hydrogen.
- The exoplanet must be in the habitable zone( Goldilocks zone ): a strip around the star is limited that would allow the existence of water in a liquid state, that is, exoplanets cannot be very close to their star, since water It would be in a gaseous state, but it cannot be too far from it for water to be in a solid state or in the form of ice.
In the coming decades, ESA’s Darwin and NASA Terrestrial Planet Finder missions contemplate exploring exoplanets to investigate the existence of oxygen, carbon dioxide and chlorophyll in them.
