This artist’s impression reveals the super-Earth exoplanet 55 Cancri e in entrance of its father or mother star. 55 Cancri e is about 40 light-years away and orbits a star barely smaller, cooler, and fewer vivid than our Sun. As the planet is so near its father or mother star, one yr lasts solely 18 hours, and temperatures on the floor are thought to succeed in round 2000 levels Celsius. Credit: ESA/Hubble, M. Kornmesser
An exoplanet is a planet that’s situated outdoors our Solar System.
While there’s at the moment no formal settlement on what precisely defines an exoplanet, the word is used to refer to planet-sized bodies that are located beyond our Solar System. By convention, exoplanets have sufficient mass to maintain a roughly spherical shape, but not so much mass that nuclear fusion is triggered in them (as is the case for stars). They might orbit one star, a pair of stars, or multiple stars — or not orbit a star at all. The categorization of exoplanets is also not formalized, but certain categories are typically used, including Super Earths, Hot Jupiters, and Mini Neptunes. The discovery of the first exoplanet was only confirmed in 1992, when two exoplanets were discovered orbiting a pulsar.
While not one of its original science goals, the Hubble Space Telescope has made a name for itself as an exoplanet explorer — in particular by studying the atmospheres of exoplanets. The chemical makeup of a planet’s atmosphere leaves a unique fingerprint on the starlight that passes through it, which Hubble can study.
An exoplanet is a planet that’s situated outdoors our Solar System. Credit: ESA/Hubble, M. Kornmesser
In 2001, astronomers utilizing Hubble introduced the primary direct detection of the environment of a planet orbiting a star outdoors our Solar System. The planet orbits a yellow, Sun-like star known as HD 209458, situated 150 light-years away. The planet was not seen immediately by Hubble. Rather, the presence of sodium, in addition to evaporating hydrogen, oxygen, and carbon, was detected in mild filtered by way of the planet’s environment when it handed in entrance of its star as seen from Earth. These observations demonstrated that with Hubble and different telescopes it’s doable to measure the chemical make-up of alien planet atmospheres and to seek for the chemical markers of life past Earth.
Exoplanet. Credit: ESA/Hubble, M. Kornmesser
In 2008 Hubble detected the primary natural molecule on an exoplanet. This breakthrough was an essential step towards sooner or later figuring out indicators of life on a planet outdoors our Solar System. Hubble discovered the tell-tale signature of the molecule methane within the environment of the Jupiter-sized exoplanet HD 189733b. Although methane has been detected on most of the planets in our Solar System, this was the first time any organic molecule was detected on a world orbiting another star.
In 2019, in an exciting discovery, Hubble data were used to detect water vapor in the atmosphere of a super-Earth within the habitable zone of its host star. K2-18b, which is eight times the mass of Earth, is now the only planet orbiting a star outside the Solar System, or exoplanet, known to have both water and temperatures that could support life.
You can learn more about how Hubble studies exoplanets in this video.
