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Top 10 Places Where Life Might Exist Beyond Earth

VO: Rebecca Brayton

Script written by Nick Roffey.

Finding life beyond Earth is one of humanity’s greatest goals. But is life possible on other planets except Earth? If so, what other places in the solar system have habitats that might support life? From planets like Mars and Venus, to Meteorites, there are some places in space that may house living things. WatchMojo counts down ten locations in the universe that could sustain life.

Special thanks to our users EmJay, TomWoodley, woodfinestuff@gmail., Hascerflef and Joao S for suggesting this idea! Check out the voting page at http://WatchMojo.comsuggest/Top%20Ten%20Places%20Life%20Might%20Exist%20Beyond%20Earth

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Transcript
Script written by Nick Roffey.

Top 10 Places Where Life Might Exist Beyond Earth


Extraterrestrial life is probably out there; we just have to find it. Welcome to WatchMojo.com, and today we’re counting down our picks for the top 10 places life might exist beyond Earth.

For this list, we’re looking at moons, planets, and other celestial bodies with conditions conducive to life.

#10: Kepler-186f

The name doesn’t really have a ring to it, but Kepler-186f is a rare find, as it’s the first discovered planet with a radius similar to Earth’s and an orbit inside its star’s habitable zone. Also known as the “Goldilocks zone,” the habitable zone is the region around a star within which a planet can support liquid water. Kepler-186f is probably about 10% bigger than Earth, and could well be terrestrial. Don’t hold your breath though; it’s 500 light-years away, so we won’t be able to detect life there for a while. The good news is that scientists estimate there are billions of other planets in the galaxy with similar conditions.

#9: Venus

The surface of our closest neighbor is currently inhospitable, a scorching desert of dust and stones beneath thick clouds of sulfuric acid. But what about billions of years ago? Before a runaway greenhouse effect cooked the planet, it may have supported liquid water. Astrobiologists believe that ancient Venusian oceans could possibly have harbored microbial life. The years have not been kind to our sister planet’s surface, but some parts of the atmosphere continue to exhibit Earth-like pressures and temperatures. Some researchers speculate that aerial microbes might have continued to exist at these altitudes with potentially habitable characteristics.

#8: Io

At first glance, Jupiter’s moon Io seems an unlikely place to find life. Caught between the gravitational pulls of Jupiter and the gas giant’s outer moons, Io is the most volcanic object in the solar system. Its surface is a patchwork of sulfurous yellow plains, volcanic peaks, and frequent lava flows. Belts produced by Jupiter’s magnetosphere blast the moon with radiation, which doesn’t bode well for life. But astrobiologist Dirk Schulze-Makuch suggests there could be water hidden underground, where microbes would be protected from the extreme conditions on the surface.

#7: Meteorites

Some researchers believe that certain microorganisms could spread to new planets, “seeding” them with life. The hypothesis, called panspermia, suggests that during massive collisions microscopic life forms are ejected into space, surviving in debris until crash landing somewhere new. So technically we could all be aliens, or at least descendants of them. In 1996, NASA astrobiologist David S. McKay controversially claimed to have discovered microfossils on a Martian meteorite in Antarctica. There’s experimental evidence to support the idea that some organisms can survive in space, including water bears (those weird microscopic animals that pretty much look like aliens). Japanese researchers are currently conducting an experiment on the International Space Station to test the hypothesis.

#6: Callisto

Where there’s water, there’s the potential for life. In 1997, NASA’s unmanned Galileo spacecraft discovered the possible existence of a salt-water ocean buried beneath the surface of Jupiter’s frigid moon, Callisto. Until the Galileo mission, scientists saw Callisto as a dead chunk of rock and ice. But the discovery of liquid water, believed to be a key ingredient for the emergence of life, turned this belief on its head. The European Space Agency is aiming to launch Jupiter’s Ice Moon Explorer, JUICE for short, in 2022 to investigate conditions of Callisto, as well as Ganymede and Europa, in detail.

#5: Ganymede

The Galileo spacecraft also discovered a subsurface sea on Callisto’s neighbor Ganymede, the largest moon in the Solar System. Ganymede was long suspected to conceal water beneath its surface. In 1996, data from Galileo confirmed this, and also demonstrated that Ganymede has a weak magnetic field generated by a liquid iron core. Scientists believe that the Jovian moon’s ocean sits between external and internal sheets of ice, or that several oceans might exist stacked on top of each other. The detection of low levels of oxygen in the atmosphere also gives hope to the possibility of life on this moon.

#4: Mars

If Venus is our “sister planet”, Mars is our brother, with a similar solar day and seasonal cycle. Before its atmosphere was stripped away, the Red Planet was warmer and wetter and could potentially have supported life. Although Mars’ oceans are long gone, in 2015 NASA discovered that liquid water continues to exist. The salt in briny ice would melt it enough for it to seep downhill. Orbiteers have detected traces of methane in the atmosphere, which some hopeful scientists interpret as the biosignature of microorganisms living below the Martian surface.

#3: Titan

Saturn’s largest moon is icy cold, but the atmosphere is rich in nitrogen, and it’s the only known place besides Earth to boast stable bodies of surface liquid. Titan’s rivers, lakes and seas are composed of methane and ethane, so if life does exist there, it would look very different than life on Earth. But scientists speculate that methane-based life forms that consume hydrocarbons could have evolved in Titan’s alien seas. In fact, lower than expected levels of hydrogen and acetylene near the surface are consistent with the presence of such organisms. NASA is currently funding a project to explore Titan’s mysterious oceans by submarine.

#2: Europa

Scientists believe that this Jovian moon’s smooth surface probably hides a vast sub glacial ocean underneath thick ice. The ocean remains liquid thanks to tidal flexing, which means friction from Jupiter’s gravitational influence dissipates as heat. Europa possesses a fragile atmosphere composed mostly of oxygen, which could feasibly reach the subterranean ocean. Europa’s smoothness suggests it’s quite young, geologically speaking, so it may still be developing. The moon has become a central focus in the search for extraterrestrial life. NASA’s Europa Clipper, which will investigate for signs of life, will be ready for launch in the 2020s.

#1: Enceladus

Like Europa, Saturn’s moon Enceladus is believed to harbor an internal ocean, discovered when the Cassini space probe flew through plumes of water vapor vented by cryovolcanoes. The main source of heat on the moon is unknown, but is contributed to by tidal flexing from the gravitational tug of nearby moon Dione. The presence of liquid water, possible hydrothermal vents, and organic molecules make Enceladus a prime candidate for extraterrestrial life. Best of all, we might find out fairly soon: German researchers are working on a probe that will bore through the ice looking for signs of life, and NASA hopes to send another space probe through the moon’s plumes.
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