Exoplanet earth-like

Earth-like exoplanets are rocky worlds located in the habitable zone of their stars, where liquid water can exist on the surface.

About this subject

Earth-like exoplanets, also called terrestrial exoplanets, are celestial bodies orbiting other stars with characteristics similar to our planet. They are primarily composed of rock and metal, with a solid surface that can support liquid water oceans. The search for these worlds is one of the main goals of modern astronomy, as they represent the most promising candidates for hosting extraterrestrial life.

The habitable zone, or 'Goldilocks Zone', is the region around a star where temperatures allow liquid water to exist. Exoplanets such as Proxima Centauri b, discovered in 2016 orbiting the closest star to the Sun, and the planets of the TRAPPIST-1 system, which has seven rocky worlds, lie in this region. As of 2025, the James Webb Space Telescope (JWST) has identified dozens of terrestrial exoplanet candidates, analyzing their atmospheres for gases like oxygen, methane, and water vapor.

Detection of an Earth-like exoplanet is primarily done through two methods: the transit method, which measures the dimming of a star when a planet passes in front of it, and the radial velocity method, which detects small stellar wobbles caused by the planet's gravity. Missions like Kepler, TESS, and PLATO have revolutionized the field, cataloging thousands of exoplanets. Despite this, finding an exact Earth twin remains challenging due to technological limitations.

Interestingly, the first exoplanet orbiting a Sun-like star was discovered in 1995, and since then over 5,000 exoplanets have been confirmed. Among them, some rocky planets in the habitable zone, such as Kepler-452b and the planets of the LHS 1140 system, draw great interest. Future studies with telescopes like the Extremely Large Telescope (ELT) may obtain direct images of these worlds, revealing details about their geology and climate.

Frequently Asked Questions

How many Earth-like exoplanets have been discovered so far?

As of 2025, over 5,000 exoplanets have been confirmed. Of these, about 50 to 100 are considered rocky and in the habitable zone, but no exact Earth twin has been found yet.

How do scientists identify if an exoplanet is Earth-like?

They analyze the planet's radius and mass (to estimate density and rocky composition) and its location in the habitable zone. Atmospheric composition is also a key indicator.

Which Earth-like exoplanet is closest to us?

Proxima Centauri b, which orbits the closest star to the Sun, about 4.2 light-years away. It is rocky and in the habitable zone, but its star is a red dwarf with frequent flares.