Welcome back! We are now half-way through the solar system in our search for the possibility of life in space apart from our home Earth. Let’s continue our journey! We will have a look at planets of Solar system like Jupiter, Saturn etc and also their moons.
Read also: Life in and beyond the solar system? Imagining the possibility– Part 1
Jupiter
Jupiter is the largest gas planet in the solar system. Jupiter is completely uninhabitable because of its immense gravity! Its atmospheric pressure is so dense that it could crush anything trying to reach its surface! FYI it is named after Roman God Jupiter and is known to ancient civilizations.
Ganymede (Jupiter’s largest Moon)
Ganymede is the biggest moon in the solar system and larger than Mercury. Oxygen has been discovered in its atmosphere, but since it has an icy exterior, chances of life surviving there are slim. However, underneath the ice, there could be water that can harbour life.
Europa (one of Jupiter’s smaller moons)
Europa is covered in a thick icy crust but under the crust, it is believed there could be free-flowing water. Plumes of hot steam have been observed shooting out of its exterior. NASA is planning to send science missions there to study its ability to expand and contract due to the gravity of Jupiter and produce heat which in turn can support life.
Saturn
Saturn is the second-largest gaseous planet in the solar system and famous for its rings which are made up of rocks and ice. Saturn has an average radius about nine times that of Earth. The planet is not suited for life since it is a gaseous planet, however, Saturn’s moon Titan can possibly support life.
Titan (one of Saturn’s moons)
Titan is almost as large as Ganymede. It is the only moon in our solar system that has an atmosphere of its own. The Cassini-Huygens Spacecraft sent to investigate the moon in the nineties discovered methane in the atmosphere of Titan. The Huygens module was parachuted down to the planet’s surface whilst the other part (Cassini) orbited the planet and its moon to observe its orbit. Cassini was recently smashed into the Saturn atmosphere in 2017. The methane produced on Titan is destroyed by excessive sunlight, but the quantity of methane that exists there indicates that it is most probably being regenerated by something else (probably some form of life) since, on Earth, methane is a byproduct of organic life.
Enceladus (a moon of Saturn)
NASA believes that Enceladus is the most likely place in the solar system to have a life other than Earth. The moon is ice-covered but underneath the ice, free water could be present.
Uranus
Uranus like Saturn and Jupiter is a gas giant and thus cannot support life due to its toxicity and high-pressure atmosphere. It has an atmosphere of Hydrogen and Helium, but since it is too far from the Sun, it is too cold to breed life.
Neptune
Since the International Astronomical Union (IAU) downgraded the planet, Pluto, to dwarf planet, Neptune is now the furthest planet from the Sun. It is also a gas giant that no solid surface like Earth or Mars, but it has a rocky core. The high atmospheric pressure is unlikely to support life, but the presence of methane on the planet suggests that maybe microscopic organisms could inhabit the planet. For us humans, it is a strict no as far as living there is concerned.
Pluto
Pluto is a rocky dwarf planet just like Mercury and Earth. It is very far from the sun and thus, it is too cold to have any free-flowing water to be found on it. The likelihood of life on the planet is very slim.
Charon (one of Pluto’s moons)
Charon is the biggest moon of the dwarf planet Pluto. It is said to have cracks on its icy surface which means that strong, warm, tidal oceans beneath its surface are likely to be found by future probes.
Eris
This dwarf planet was at one time considered as the tenth planet of our solar system. The atmosphere there is considered to contain methane, but we are yet to observe it closely. Current observations have been done only via Earth-based telescopes
Sedna
It is a dwarf planet found in the intergalactic space beyond Pluto. If it has life, it can only be one that is not dependent on solar power which means the planetoid must be able to generate its own heat from within its core to sustain life.
List of potentially habitable exoplanets beyond the solar system
In astronomy and astrobiology, the circumstellar habitable zone (CHZ or sometimes “ecosphere”, “liquid-water belt”, “HZ”, “life zone” or “Goldilocks zone”) is the region around a star where a planet with sufficient atmospheric pressure can maintain liquid water on its surface.
A potentially habitable planet implies a terrestrial planet within the circumstellar habitable zone and with conditions roughly comparable to those of Earth (i.e. an Earth analogue) and thus potentially favourable to Earth-like life. However, the question of what makes a planet habitable is much more complex than having a planet located at the right distance from its host star so that water can be liquid on its surface: various geophysical and geodynamical aspects, the radiation, and the host star’s plasma environment can influence the evolution of planets and life if it originated.
In November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way, 11 billion of which may be orbiting Sun-like stars. – Source: Wikipedia
Here is a list of the exoplanets (extrasolar planets) that are more likely to be able to sustain life. Please note that research is ongoing to ascertain whether these planets can actually support the life of any kind or not. An extra-solar planet is a planet doesn’t orbit our Sun but orbits a star somewhere else in the universe within the vast cosmos.
List of exoplanets in the conservative habitable zone (are more likely to have a rocky composition)
- Proxima Centauri b
- Gliese 667 Cc
- Kepler-442b
- Kepler-452b
- Wolf 1061c
- Kepler-1229b
- Kapteyn b*
- Kepler-62f
- Kepler-186f
- Luyten b
- TRAPPIST-1d
- TRAPPIST-1e
- TRAPPIST-1f
- TRAPPIST-1g
- LHS 1140 b
- Kepler-1638b
List of exoplanets in the optimistic habitable zone (are less likely to have a rocky composition or maintain surface liquid water)
- Kepler-438b
- Kepler-296e
- Kepler-62e
- Gliese 832 c
- K2-3d
- Kepler-1544b
- Kepler-283c
- Tau Ceti e*
- Gliese 180 c
- Kepler-440b
- Gliese 180 b
- HD 40307 g
- Gliese 163 c
- K2-18b
- Kepler-61b
- Kepler-443b
- Kepler-22b
- Gliese 422 b*
- K2-9b
- Gliese 3293 c
- Kepler-298d
- Kepler-174d
- Kepler-296f
- Gliese 682 c
- KOI-4427 b*
- Kepler-1090b
- Ross 128 b
- HD 20794 e*
- Gliese 625 b
- HD 219134 g*
* represents an unconfirmed planet or planet candidate.
Conclusion
Currently, there is only one confirmed location at the moment that contains life and that is our very own home planet, Earth! Yes, we may inhabit other planets like mars someday and discover life forms there, but since Mars is itself a dead planet, chances of finding life there are very, very slim! On Earth, only micro-bacterial life has been discovered to exist at very high altitudes, but it doesn’t rule out the possibility that life could exist on gas giants and Venus. Exo-planets are currently the most likely place for life to exist in the Universe, but to get there, we would have to build freakishly fast spacecraft to make us reach there.
Until then, Earth has the right ingredients to support life, but with a massive seven billion humans and an untold number of other organisms inhabiting it, the planet is choking to its eventual death due to excessive pollution. We need to protect our home planet first before we even plan to colonize other areas in the cosmos!We better start conserving our resources here before it is too late and Earth dies a slow death.
