The dream undercut

Wikipedia has a list of potentially habitable exoplanets and possible exoplanets. The list is based on estimates of habitability by the Habitable Exoplanets Catalog (HEC), and data from the NASA Exoplanet Archive. The HEC is maintained by the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo.

Surface planetary habitability is thought to require orbiting at the right distance from the host star for liquid surface water to be present, in addition to various geophysical and geodynamical aspects, atmospheric density, radiation type and intensity, and the host star’s plasma environment.

In astronomy and astrobiology, the circumstellar habitable zone (CHZ or sometimes “ecosphere”, “liquid-water belt”, “HZ”, “life zone” or “Goldilocks zone”) is the region around a star where a planet with sufficient atmospheric pressure can maintain liquid water on its surface.

However, the question of what makes a planet habitable is much more complex than having a planet located at the right distance from its host star so that water can be liquid on its surface: various geophysical and geodynamical aspects, the radiation, and the host star’s plasma environment can influence the evolution of planets and life, if it originated.

Based on Kepler space mission data, there could be on the order of 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way.

A 2015 review concluded that the exoplanets Kepler-62fKepler-186f and Kepler-442b were likely the best candidates for being potentially habitable. Kepler-186f is similar in size to Earth with a 1.2-Earth-radius measure and it is located towards the outer edge of the habitable zone around its red dwarf.

In 2017, NASA’s Spitzer Space Telescope revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.

The discovery sets a record for greatest number of habitable-zone planets found around a single star outside our solar system. All these seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.

The dream is to find not just life, but to discover evolved-intelligent-human-like beings, or even better, the conditions for human life without pesky competitors. Never mind that all possibilities are hundreds of million light-years away and that we are compromising the chances of human civilizations lasting not beyond a few centuries more.

About arnulfo

veterano del ciberespacio
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