Universe Guide

Life on other Planets and Moons in the Solar System

At present the only planet or moon that is known to support life in The Solar System is Earth. It is not to say that life doesn't or ever existed on other planets and moons, its just we've not finished checking everywhere yet and have not found any evidence yet. There are eight planets and an untold number of moons that have to be checked. The Earth has one moon but Jupiter has sixty plus moons.


Mercury, the closest planet to The Sun, is far too hot and far too cold to support any life. It may have a thin atmosphere of oxygen but the heat from the Sun would vapourise and prevent any life forms from forming. It is safe to say that there is no life on the planet. There might be life forms deep under ground but that is highly unlikely. The side of Mercury that faces the Sun will be too hot and the side that faces away from the Sun will be too cold therefore it has no ability to support life.


Venus was once thought to contain life given its near proximity planet and it is within the Goldilocks Zone. The Goldilocks Zone is the area of space that is not too far and not too near but just the right distance from the Sun for life to exist. Eagle comics in United Kingdom had a race of aliens known as the Treens in the Dan Dare comic stories that hid under the thick atmosphere. When space probes primarily from Russia or as it was known then, the Soviet Union sent Venera probes to the planet, they discovered that the planet was hot and a sulphuric atmosphere, an environment in which no life could exist because it was too toxic.

However, on Earth, life has been known to exist in the most extreme of locations, near hot spurs under water but the atmosphere is too toxic at ground level. Those life forms are known as Etremophiles. There is a possibility that life forms, bacterial could life high in the atmosphere, at the very edge where the atmosphere is may just be right to support life. Seeker Neither Venus nor Mercury have any moons which could support life.


Earth, the third planet from the Sun, our home in the Solar System is the only planet or moon that is known to have the ability support support life. Earth has the right ingredients and is sufficiently far enough from the Sun to have just the right temperature to support life. At present, there are about seven billion humans and an untold number of other animals that could run into millions of other life forms types including dogs, cats and Micro-Organisms. Micro-organisms include viruses and bacteria, however it depends on whether you class them as life. the moon has no atmosphere and therefore no life could ever exist on the planet. Whilst the moon was created by a planetoid smashing into the early Earth, life was not thought to have existed at the time of the smash and so no viral pollution would have ended up on the Moon.


Panspermia is the theory that life didn't originate on Earth but hitched a ride on a comet or an asteroid. If we did, there is a chance that life like ours could exist out there in the depths of the Universe, waiting to be discovered.


There has always been speculation as to whether there is life on Mars or whether there had and no longer is life on Mars. The planet has featured in many science fiction stories as the home of warrior races that who wish to conquer the Earth such as in War of the Worlds by H.G. Wells. In Mars Attacks, the Martians lived underground whilst they plotted their conquest of our planet as they could not breathe on the surface. We've been sending probes to the planet for tens of years but have not found any concrete evidence. The best evidence of life that scientists are hoping for is bacterial life forms. As mentioned previously, bacteria on Earth have been found in the most extreme of locations. Even though probes that are sent to outer space are sterilised to ensure that they don't contain hitch-hiking bacteria, it is not 100% fail proof and Earth bacteria could in the most extremely rare case survive on the planet. The planet has ice caps on its north and south poles, bacterial could be encased inside them.

One theory is that life did take off on Mars but lost its ability to support life. Mars lost its atmosphere and scientists are looking into why. Ref: Time On Earth, we have a magnetic field that protects us from the Sun's radiation however on Mars, its shielding has disappeared and therefore advanced life would be killed off on the planet. There is a new race between the nations to get a community on Mars but we would need to build living quarters that would shield us from the Suns power, not an easy thing to do. Kim Stanley Robinson wrote about a trilogy of books (Red Mars, Green Mars, Blue Mars) about setting up on Mars and terraforming the planet. Terraforming the planet would be expensive and whether it could actually be done would need to be answered.

Mars is currently in the the Goldilocks Zone and therefore in theory life could have started on the red planet. The picture below is a N.A.S.A. artists impression of Kepler-22 solar system, in the bottom picture, you will see that Mars is in the Goldilocks zone. Mars doesn't have a magnetic field so can't protect against dangerous particles from the Sun. It used to and have an atmosphere but its all gone. ref: The Atlantic

Goldilocks Zone

Mars is a cold planet, humans wishing to survive will move to that planet before having to move again when the Sun expands further. Hopefully before we have to move from Earth or Mars, we will have created faster than light travel and have left the Solar System, having set up on an Extrasolar Planet somewhere out there in the Cosmos. An extrasolar planet is a planet doesn't orbit our Sun but orbits a star somewhere else in the Universe.

The two moons of Mars, Deimos and Phobos are thought to be two Asteroids that flew too close to Mars and were pulled into orbit around the red planet. Scientists now believe that they were created when something crashed into the planet. Astronomy Now.

Asteroid Belt

The asteroid belt contains an unknown number of rocky objects, none of which have been proven to have the ability to support life. The rocks are believed to have been debris left over from the creation of the solar system that couldn't form into a rocky planet because of the influence of Jupiter, the largest planet in our solar system. The largest object is Ceres, now classified as a dwarf planet. Scientists now believe there is water vapour on Ceres but not life. Ref:Sci-News. The chances of any life on any object within the asteroid belt is low, next to zero.


Jupiter is the largest planet in the solar system, some theorized it is a failed star that didn't have enough energy or mass to become a star. It is thought to have a small rocky core but has been proven outright yet Ref: Universe Today. The atmosphere has high pressure and anything would be crushed to a pea by the strength of the gravity on the planet. The best chance of life existing here would be on a moon that is in orbit around the planet. Jupiter's ability to support life is therefore zero.


Ganymede is the biggest moon in the solar system, it is even bigger than the planet Mercury. Oxygen has been discovered in the atmosphere on the planet. Like Europa, Ganymede has an icy exterior but underneath the ice could be water if the planet core is hot enough to allow water to free flow. ref:Discovery

In addition to being bigger than Mercury, it is the largest planetary satellite in the Solar System. Ganymede is larger than our Moon. The Moon is the largest satellite in comparison to the object it orbits.


Europa is long seen as being a possibly moon that has the ability to support life forms. It has a icy crust which plumes of steam have been seen shooting out of its exterior. In the film 2010, sequel to 2001, a Space Odyssey, Europa is the moon where Earth is told to avoid but they could visit every other planet and moon in the solar system YouTube.

The moon is covered in a thick icy crust but under the crust, it is believed there could be free flowing water. it is one of the most likely candidates for life to exist on other than the Earth. Future N.A.S.A. science missions are being planned to visit the moon to study it. The first voyage to the planet would be to survey the planet from a satellite with ice penetrators. Later missions would be to break the crust and send down a probe. Sending a probe into the ice crust does open possible ethical questions as we might be introducing a virus to their ecosystem which would kill the life forms off. An example of this is that when Europeans went to the Americas, they unwittingly introduced diseases which the natives had no natural resistance to. One of the things that life needs is heat and heat is generated on Europa by the gravity of Jupiter which causes the planet to expand and contract. Ref:Caltech


Saturn is the second largest planet in the solar system, the first being Jupiter. Saturn is famous for its rings which all four gas giants. Saturn's rings are more prominent than the other planets in the Solar System. Ref:CalTech.

Like Jupiter which is also a gas planet, Saturn is likely to have a rocky core. It doesn't have a breathable atmosphere unlike Bespin, the gas giant in Star Wars. The rings are made up of rocks and ice and neither of those would be sufficient to support life. The most likely place to have the ability to support life is on the atmospheric moon of Titan.


Although its name might create the impression it is the biggest, Titan is not bigger than the Jupiter moon Ganymede. Titan is the only moon in the solar system with an atmosphere and therefore of interest to scientists as to whether the moon has the ability to support life. NASA/ESA/Italian Space Agency sent Cassini-Huygens Spacecraft to the moon in the nineties to investigate the planet. The space probe was two parts, one (Huygens) was parachuted down to the planet whilst the other part orbited the planet and its moon. Cassini was smashed into Saturn in the middle of September 2017 so as not to contaminate any of the moons.

Although Cassini is over, the project is still in progress as it reviews the data that it has received so far. As of yet no reports of life has been reported yet. Cassini mission was not equipped with equipment to search for organic compounds so it is unlikely anything will be found as part of the mission. Ref:Wiki. According to ESA, there has been methane discovered in the atmosphere which is destroyed by sunlight but the quantities of methane that exists on the planet must indicate it is being regenerated by something else. Methane on Earth is a byproduct of organic life. Ref:E.S.A.


The Saturnian moon of Enceladus is being hailed as the most likely place in the solar system to have the ability to support life in the Solar System other than Earth. According to press reports in early April 2017, N.A.S.A believes this could be the place to look further. The moon is ice covered but under the ice, they believe there could be free water. Where there's water, there could be life. Further analysis of the planet needs to be carried out, another probe would need to be sent to carry out the necessary experiments needed. Ref: BBC


Uranus is a gas giant and like the other gas planets has a large number of moons. Uranus does not have the ability to support life as we know it as it is too toxic for and it has a high pressure atmosphere. Uranus is too far from the Sun and therefore cold and life that we know of needs heat. According to Universe Today, life could possibly but unlikely exist on the planet. The planet has an atmosphere of Hydrogen and Helium but more importantly Methane. Ref:Universe Today. Methane would have needed to have been produced somehow but probably not through the same way as it is on Earth.


At present due to the International Astronomical Union (IAU) downgrading the planet Pluto to dwarf planet, Neptune is currently the furthest planet from the Sun and Earth for that matter as well. Neptune is a large gas giant, blue in colour and with an untold number of moons. Whilst this site might detail 14 of its moons, they'll be quite a few more, some undiscovered.

Back to the planet at hand, the planet doesn't have a solid surface like that of Earth or Mars, it will most likely have a rocky core, not one on which life could exist on. The atmosphere would be heavy pressure and any life forms would need to have a strong body to withstand. The atmosphere contains methane which on Earth is a by-product of organic material so extremely small but possible something living could have created it. Like with all the other gas giants, if anything does live there, it would be microscopic organisms. Ref:Mysterious Universe


Up until the mid-noughties, Pluto was classified as a planet but then it was downgraded after a vote by the I.A.U. What prompted the downgrading was the discovery of Eris, an object that was at first seen as being bigger than Pluto. Unlike the other outer planets, Pluto is a rocky planet like Mercury and Earth. We're only just learning about the planet since N.A.S.A. sent the New Horizons space probe out to study it for the first time. It is so far from the Sun, the Sun is nothing more than a dot. Pluto is far too cold to allow for water to be free flowing on the planet but water has been found on the planet by the New Horizons probe which does increase the likelihood of life. Ref: Express.


Charon is the biggest moon of the dwarf planet Pluto and the first Plutonian moon to be discovered. According to NASA scientists, there is a remote chance that the moon could contain life under its icy crust. According to scientists analyzing the moon, cracks on the surface of the frozen moon say it points to the existence of strong, warm, tidal oceans beneath. As the discovery is new, the New Horizons craft would not have been kitted out with equipment to check for any possible life on the moon. Ref:Daily Mail


The one time tenth planet provisionally called Xena after the Warrior Princess television character is so far away from Earth that we don't know much about the dwarf planet. The only thing we do know is that its about the same size of the planet Pluto. The only observations we have of the planet and its moon is from Earth based telescopes. At the moment, nothing is being sent out towards the planet. It is too far away from Pluto for the New Horizons to be redirected to it. The atmosphere at present is said to contain methane which could indicate a slight chance for its ability to support life. The inner core of the planet could be heated from the core. Ref:Mysterious Universe.


Sedna is one of the furthest objects in our solar system. Technically it is not part of the Solar System because it is so far from Pluto that it is intergalactic space. For any life as we know it to exist, the life would need to be not dependant on solar power and the planetoid must be able to generate its own heat source from within. Unless we get faster than light travel, there is no change of any space probe visiting the planet.

Earth is the only planet in the Solar System that has the ability to support life.

There is only one confirmed location at the moment that contains life presently and that is our home, planet Earth. Unless there is free flowing underwater activity on some of the moons in our solar system, the only life forms that we could possibly find elsewhere is bacterial.

One day, we might get to Mars and discover that life once did exist but when the planet died, life died too. On Earth, high in the sky, talking at cloud level, micro-bacterial life has been discovered to exist which raises the possibility that life could exist on gas giants and Venus Ref: LiveScience. The most likely place for life exist in the Universe is on extrasolar planets.

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Ccol04Tuesday, 31st October 2017 8:11:24 PM
hey, if there is water, water= H2O, as in 1 hydrogen, 2 OXYGEN. if there is water, there is oxygen, RIGHT!?!
Ccol04Tuesday, 31st October 2017 8:09:09 PM
well, Marco, how would it stay up??? 1. say that its true, how would, a bird 4 example, fly??? A BIRD MUST LAND!! and, I bet, there is a possibility of it, as it probably has stronger gravity in the middle, pulling in materials, but, how would life be there with that strong gravity??? I think Europa would be a good suit, but as it is probably cold, and infact IS COVERED in ice, (meltable), its a good choice.
Scientist Abhishek Kumar TripathiSunday, 6th May 2018 10:14:39 AM
This information is really very helpful for me. I wish to be life there in any moon or any planet. I think uncountable stars are there and if we talk about parallel universe then you know there could be life on the third number of each planet... or it may be that every life is caused of asteroids collision having enough water with any planet or moon.
MarcoMonday, 27th March 2017 2:07:39 AM
Why is it that life could not live within the gas planets? In other words, how do we know that the gas atmosphere is not concealing an interior that supports some kind of life? Has anybody confirmed there is no ground to walk on underneath that gas? Is it possible the gas acts for the living on that planet as oxygen works for us? I know this is kind of far fetched but I think our biggest setback is that we cannot seem to get our brains to think outside the box. I believe whatever intelligent life we do find will be completely different than us and their life will require completely different "ingredients" than us, like icy cold atmospheres per se
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