Habitable Zone. An example of a system based on stellar luminosity for predicting the location of the habitable zone around various types of stars. Planet sizes, star sizes, orbit lengths, and habitable zone sizes are not to scale. In astronomy and astrobiology, the circumstellar habitable zone (CHZ) (or simply the habitable zone), colloquially known as the Goldilocks zone, is the region around a star within which planetary-mass objects with sufficient atmospheric pressure can support liquid water at their surfaces.[1][2] The bounds of the CHZ are calculated using the known requirements of Earth's biosphere, its position in the Solar System and the amount of radiant energy it receives from the Sun.
Due to the importance of liquid water to life as it exists on Earth, the nature of the CHZ and the objects within is believed to be instrumental in determining the scope and distribution of extraterrestrial life and intelligence. History[edit] Determination of the circumstellar habitable zone[edit] Terraforming. An artist's conception shows a terraformed Mars in four stages of development. Terraforming (literally, "Earth-shaping") of a planet, moon, or other body is the theoretical process of deliberately modifying its atmosphere, temperature, surface topography or ecology to be similar to the biosphere of Earth to make it habitable by Earth-like life. The term "terraforming" is sometimes used more generally as a synonym for planetary engineering, although some consider this more general usage an error.
[citation needed] The concept of terraforming developed from both science fiction and actual science. The term was coined by Jack Williamson in a science-fiction story (Collision Orbit) published during 1942 in Astounding Science Fiction,[1] but the concept may pre-date this work. History of scholarly study[edit] In March 1979, NASA engineer and author James Oberg organized the First Terraforming Colloquium, a special session at the Lunar and Planetary Science Conference in Houston.
Mars[edit] Planetary habitability. Understanding planetary habitability is partly an extrapolation of the Earth's conditions, as this is the only planet currently known to support life. Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and sustain life. Life may develop directly on a planet or satellite or be transferred to it from another body, a theoretical process known as panspermia.
As the existence of life beyond Earth is currently uncertain, planetary habitability is largely an extrapolation of conditions on Earth and the characteristics of the Sun and Solar System which appear favourable to life's flourishing—in particular those factors that have sustained complex, multicellular organisms and not just simpler, unicellular creatures. Research and theory in this regard is a component of planetary science and the emerging discipline of astrobiology. Suitable star systems[edit] Spectral class[edit] They live at least a few billion years, allowing life a chance to evolve. NASA's Kepler Mission Confirms Its First Planet in Habitable Zone of Sun-like Star. Click image for multiple resolutions. This diagram compares our own solar system to Kepler-22, a star system containing the first "habitable zone" planet discovered by NASA's Kepler mission.
Image credit: NASA/Ames/JPL-Caltech NASA's Kepler mission has confirmed its first planet in the "habitable zone," the region where liquid water could exist on a planet's surface. Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets. The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive. Kepler-22b is located 600 light-years away.
Planetary Habitability Laboratory @ UPR Arecibo.