We could be on the verge of answering one of the essential questions of humanity that has captivated our minds for centuries. As we advance in technology the search for extraterrestrial life becomes more sophisticated and promising. But the real frosting on the cake would be finding any signs of an intelligent alien civilization. In an interview with astrowatch.
This hypothesis relies on the vast size and consistent physical laws of the observable universe. According to this argument, made by scientists such as Carl Sagan and Stephen Hawking as well as well-regarded thinkers such as Winston Churchill  it would be improbable for life not to exist somewhere other than Earth.
Alternatively, life may have formed less frequently, then spread—by meteoroidsfor example—between habitable planets in a process called panspermia. Numerous discoveries in such zones since have generated numerical estimates of Earth-like planets —in terms of composition—of many billions.
One of the study authors, Sam Levin, notes "Like humans, we predict that they are made-up of a hierarchy of entities, which all cooperate to produce an alien.
At each level of the organism there will be mechanisms in place to eliminate conflict, maintain cooperation, and keep the organism functioning.
We can even offer some examples of what these mechanisms will be. It has been suggested that this capacity arises with the number of potential niches a planet contains, and that the complexity of life itself is reflected in the information density of planetary environments, which in turn can be computed from its niches.
Sufficient quantities of carbon and other elements, along with water, might enable the formation of living organisms on terrestrial planets with a chemical make-up and temperature range similar to that of Earth.
It is also conceivable that there are forms of life whose solvent is a liquid hydrocarbonsuch as methaneethane or propane. These six elements form the basic building blocks of virtually all life on Earth, whereas most of the remaining elements are found only in trace amounts.
The carbon atom has the unique ability to make four strong chemical bonds with other atoms, including other carbon atoms.
These covalent bonds have a direction in space, so that carbon atoms can form the skeletons of complex 3-dimensional structures with definite architectures such as nucleic acids and proteins.
Carbon forms more compounds than all other elements combined. The great versatility of the carbon atom makes it the element most likely to provide the bases—even exotic ones—for the chemical composition of life on other planets. Planetary habitabilityHabitability of natural satellitesand Exobiology Some bodies in the Solar System have the potential for an environment in which extraterrestrial life can exist, particularly those with possible subsurface oceans.
According to NASA's Astrobiology Strategy, "Life on other worlds is most likely to include microbes, and any complex living system elsewhere is likely to have arisen from and be founded upon microbial life. Important insights on the limits of microbial life can be gleaned from studies of microbes on modern Earth, as well as their ubiquity and ancestral characteristics.
If extraterrestrial life was found on another body in the Solar Systemit could have originated from Earth just as life on Earth could have been seeded from elsewhere exogenesis. The first known mention of the term 'panspermia' was in the writings of the 5th century BC Greek philosopher Anaxagoras.
The Nobel prize winner Francis Crickalong with Leslie Orgel proposed that seeds of life may have been purposely spread by an advanced extraterrestrial civilization,  but considering an early " RNA world " Crick noted later that life may have originated on Earth.
Life on Venus In the early 20th century, Venus was often thought to be similar to Earth in terms of habitability, but observations since the beginning of the Space Age have revealed that Venus's surface is inhospitable to Earth-like life.
However, between an altitude of 50 and 65 kilometers, the pressure and temperature are Earth-like, and it has been speculated that thermoacidophilic extremophile microorganisms might exist in the acidic upper layers of the Venusian atmosphere.
Life on 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. Nevertheless, present conditions on Mars' subsurface may support 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.
Life on Europa Internal structure of Europa. The blue is a subsurface ocean. Such subsurface oceans could possibly harbor life. 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.
Enceladus Enceladusa 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 temperature and density of the plumes indicate a warmer, watery source beneath the surface. Life on Titan Titanthe largest moon of Saturnis 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. Fred Hoyle and Chandra Wickramasinghe have proposed that microbial life might exist on comets and asteroids.A Tale of 2 Habitable Planets.
New study explores how life on one exoplanet could spread to its neighbor. Scientists shrink chemistry lab to seek evidence of life on Mars Date: May 24, Source: NASA/Goddard Space Flight Center Summary: An international team of scientists has created a tiny.
Take part in the search for life on vetconnexx.com Learn about the Fermi paradox, the search for extraterrestrial intelligence (SETI) and astrobiology.
Jul 18, · From CCTV footage of two believed men in black looking for UFO witnessers to the believed sighting of extraterrestrials on the moon and orbiting our planet.
Here are 5 strongest signs of Alien. But while Anonymous is right to point out that NASA is probably closer than ever in human history to discovering extraterrestrial life, it may be a leap to say concrete evidence for it exists.
Extraterrestrial life Its existence is currently purely hypothetical as there is yet no evidence of any planets that can support life, or actual extraterrestrial life that has been widely accepted.