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Geoffrey A. Landis of NASA's Glenn Research Center has summarized the perceived difficulties in colonizing Venus as being merely from the assumption that a colony would need to be based on the surface of a planet: However, viewed in a different way, the problem with Venus is merely that the ground level is too far below the one atmosphere level.
Planetary habitability in the Solar System is the study that searches the possible existence of past or present extraterrestrial life in those celestial bodies. As exoplanets are too far away and can only be studied by indirect means, the celestial bodies in the Solar System allow for a much more detailed study: direct telescope observation, space probes, rovers and even human spaceflight.
Nevertheless, life need not originate during this stage of stellar evolution for it to be detected. Once the star becomes a red giant, and the habitable zone extends outward, the icy surface would melt, forming a temporary atmosphere that can be searched for signs of life that may have been thriving before the start of the red giant stage. [100]
Even though Venus is violently hostile to life, the planet is so similar to our own in makeup and location that it's often referred to as Earth's twin Venus may once have been habitable. Now it ...
Today's Venus can be described as hellish: there is almost no water vapor, the carbon dioxide atmosphere is 90 times as thick as that on Earth and temperatures can reach a scorching 864 degrees.
Until the mid-20th century, the surface environment of Venus was believed to be similar to Earth, hence it was widely believed that Venus could harbor life. In 1870, the British astronomer Richard A. Proctor said the existence of life on Venus was impossible near its equator, [11] but possible near its poles.
Astronomers have found a potential sign of life high in the atmosphere of neighboring Venus: hints there may be bizarre microbes living in the sulfuric acid-laden clouds of the hothouse planet.
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.