Question

can there be life on other planet except earth?

write 1000 words essay

Answer 1

Extraterrestrial life occurs in planets other than earth.Life may have emerged independently at many places throughout the universe. According Big Bang theory the the planetsemerged from an explosion of unimaginable energy. Planets including Earth evolved from it. During the the beginning the conditions of many planets were moral similar.This suggest the existence of extraterrestrial life in planets other than earth

Mercury

There may be scientific support , for considering that parts of the planet Mercury may have been habitable, and perhaps that life forms, albeit likely primitive microorganisms, may have existed on the planet.

Venus

Venus was considered to be similar to Earth for habitability, but observations since the beginning of the Space Age revealed that the Venus surface temperature is around 872 °F (467 °C), making it inhospitable for Earth-life.Likewise, the atmosphere of Venus is almost completely carbon dioxide, which can be toxic to Earth-like life. Between the altitudes of 50 and 65 kilometers, the pressure and temperature are Earth-like, and it may accommodate thermoacidophilic extremophile microorganisms in the acidic upper layers of the Venusian atmosphere. Furthermore, Venus likely had liquid water on its surface for at least a few million years after its formation.

Mars

Life on Mars has been long speculated. Liquid water is widely thought to have existed on Mars in the past, and now can occasionally be found as low-volume liquid brines in shallow Martian soil.The origin of the potential biosignature of methane observed in Mars' atmosphere is unexplained, although hypotheses not involving life have also been proposed.

There is evidence that Mars had a warmer and wetter past: dried-up river beds, polar ice caps, volcanoes, and minerals that form in the presence of water have all been found. Nevertheless, present conditions on Mars' subsurface may support life. Evidence obtained by the Curiosity rover studying Aeolis Palus, Gale Crater in 2013 strongly suggests an ancient freshwater lake that could have been a hospitable environment for microbial life. The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on Mars is now a primary NASA objective.

Ceres

Ceres, the only dwarf planet in the asteroid belt, has a thin water-vapor atmosphere.The vapor could have been produced by ice volcanoes or by ice near the surface sublimating (transforming from solid to gas).Nevertheless, the presence of water on Ceres had led to speculation that life may be possible there. It is one of the few places in our solar system where scientists would like to search for possible signs of life. Hence, it is a possibility that the planet could support life to very small microbes similar to bacteria. Although the planet might not have living things today, there could be signs it harbored life in the past.

Jupiter

Carl Sagan and others in the 1960s and 1970s computed conditions for hypothetical microorganisms living in the atmosphere of Jupiter. The intense radiation and other conditions, however, do not appear to permit encapsulation and molecular biochemistry, so life there is thought unlikely. In contrast, some of Jupiter's moons may have habitats capable of sustaining life. Scientists have indications that heated subsurface oceans of liquid water may exist deep under the crusts of the three outer Galilean moons—Europa,Ganymede,and Callisto.The EJSM/Laplace mission is planned to determine the habitability of these environments.

Europa

Internal structure of Europa. The blue is a subsurface ocean. Such subsurface oceans could possibly harbor life.

Jupiter's moon Europa has been subject to speculation about the existence of life due to the strong possibility of a liquid water ocean beneath its ice surface.Hydrothermal vents on the bottom of the ocean, if they exist, may warm the water and could be capable of supporting nutrients and energy to microorganisms.It is also possible that Europa could support aerobic macrofauna using oxygen created by cosmic rays impacting its surface ice.

The case for life on Europa was greatly enhanced in 2011 when it was discovered that vast lakes exist within Europa's thick, icy shell. Scientists found that ice shelves surrounding the lakes appear to be collapsing into them, thereby providing a mechanism through which life-forming chemicals created in sunlit areas on Europa's surface could be transferred to its interior.

Saturn system

Like Jupiter, Saturn is not likely to host life. However, Titan and Enceladus have been speculated to have possible habitats supportive of life.

Enceladus

Enceladus, a moon of Saturn, has some of the conditions for life, including geothermal activity and water vapor, as well as possible under-ice oceans heated by tidal effects. The Cassini–Huygens probe detected carbon, hydrogen, nitrogen and oxygen—all key elements for supporting life—during its 2005 flyby through one of Enceladus's geysers spewing ice and gas. The temperature and density of the plumes indicate a warmer, watery source beneath the surface.

Titan

Titan, is the only known moon in the Solar System with a significant atmosphere. Data from the Cassini–Huygens mission refuted the hypothesis of a global hydrocarbon ocean, but later demonstrated the existence of liquid hydrocarbon lakes in the polar regions—the first stable bodies of surface liquid discovered outside Earth.Analysis of data from the mission has uncovered aspects of atmospheric chemistry near the surface that are consistent with—but do not prove—the hypothesis that organisms there if present, could be consuming hydrogen, acetylene and ethane, and producing methane.

Small Solar System bodies

Small Solar System bodies have also been speculated to host habitats for extremophiles. Fred Hoyle and Chandra Wickramasinghe have proposed that microbial life might exist on comets and asteroids.

Other bodies

Models of heat retention and heating via radioactive decay in smaller icy Solar System bodies suggest that Rhea, Titania, Oberon, Triton, Pluto, Eris, Sedna, and Orcus may have oceans underneath solid icy crusts approximately 100 km thick. Of particular interest in these cases is the fact that the models indicate that the liquid layers are in direct contact with the rocky core, which allows efficient mixing of minerals and salts into the water. This is in contrast with the oceans that may be inside larger icy satellites like Ganymede, Callisto, or Titan, where layers of high-pressure phases of ice are thought to underlie the liquid water layer.

Hydrogen sulfide has been proposed as a hypothetical solvent for life and is quite plentiful on Jupiter's moon Io, and may be in liquid form a short distance below the surface.