11 Celestial Bodies In Our Solar System That Might Possibly Have Life
Humanity's search for life in outer space has been going on for decades. The fact that nobody has answered our calls yet doesn't mean that we should or will give up; especially when we have all these exciting possibilities!
Scientists are very optimistic about finding life in space; because even in our solar system, there are celestial bodies that can possibly host a form of life. Considering this, one cannot help but think about what the case could be in other solar systems.
While searching for life, one of the first criterion is water. Life can be based on many things: maybe other living things don't need water, but another liquid; or no liquid at all. However, as humanity, we know that water is indeed a necessary material for life. Hence, the planets which have water are the most likely candidates for hosting a life form.
1. Enceladus
Enceladus, which is the sixth biggest moon of Saturn with its 252 km diameter, is thought to have large amounts of water under its surface. During the observations made in 2005, it was found out that there are big ice bodies on its surface, especially around geysers. Scientist assume that the water under the surface can be kept in the liquid form because of the gravitational interactions Enceladus has with Saturn and with other moons.
2. Europa
Europa, which was first discovered by Galileo Galilee 400 years ago, is one of Jupiter's moons. It is one of the celestial bodies in our solar system that is most likely to have life; so much that its odds even beat those of Mars. Scientist think that there is a gigantic ocean stretching as wide as the moon itself. It is very well likely that Europa has more water than the Earth.
The problem is that this ocean lies under an ice layer, whose surface thickness varies between 10 and 30 km. First of all, it is impossible to send a device to Europa that is technologically advanced enough to dig that deep and search for life. Secondly, Europa's ocean cannot get any sun light, which cancels out the possibility of photosynthesis.
Still, there can be life on Europa due to the geothermal energy coming out of the hydro thermal vents, possibly located at the surface of the ocean. It is known that this is the case for Earth: there are living creatures in the hydro thermal vents down at the surfaces of Earth's oceans. Moreover, Europa is known to have all of the vital elements for life: carbon, hydrogen, nitrogen and oxygen.
3. Titan
Titan, which is the biggest moon of Saturn with its diameter of 2576 km, is even bigger than Mercury. It is the only celestial body other than Earth that is known to have liquid on its surface. It is also the only natural satellite that is known to have an intense atmosphere.
We have mentioned that there is liquid there, however it is unfortunately not water, but hydrocarbon and methane. Therefore all of Titan's rivers, lakes and oceans are completely made up by those two. All of this causes its atmosphere to consist of 98% nitrogen and the rest, gases such as methane and ethane. This is a very lethal atmosphere and environment.
On Titan, there are clouds and hence rain; however it isn't the rain as we know it. It is liquid form of gases. It also has seasons and winds, but the temperature is about -180 Celsius degrees. Although it isn't suitable for us -yet- there might be some life forms that have adapted to methane and hydrocarbon.
We know everything we know about Titan thanks to the Huygens spacecraft!
4. Callisto
Callisto, which too, was first discovered by Galileo Galilee 400 years ago, is the second biggest moon of Jupiter, and the third biggest in our solar system.
It is known as the most suffering moon of our solar system. It owes this reputation to having been hit by countless asteroids and therefore its surface is full of craters. The surface temperature is around -138 degrees and it is thought to be dead, which means that there is no geological activity.
Callisto was one of the first land bodies formed in the solar system, and its surface is believed to have been dead for quite a long time. To be more specific, it is thought that there hasn't been any changes on its surface in the last 4 billion years. Its very thin atmosphere consists of carbon-dioxide and molecular oxygen.
If you feel like asking the obvious question 'Why look for life on a dead moon?'; scientists think that there might be an ocean 100 km beneath the surface of Callisto.
5. Ganymede
Ganymade, which is the biggest moon in our solar system, and therefore of Jupiter, is likely to have an ocean 100-150 km deep down under its surface. It is also very well possible that the amount of water exceeds that of Earth.
As it is the only moon that has its own magnetic field, it also enjoys having its own auras. The scientists who studied these auras assume that there is a huge ocean of salty water under the surface that affects this magnetic field.
6. Io
Io, which could be one of the ugliest moons ever, rotates around Jupiter; and is one of the least likely celestial bodies that might have life. The reason for that is the highly intensive volcanic activity. It is also exposed to lots and lots of radiation because of Jupiter.
Scientists think that there are more than 400 active volcanoes, which makes Io rich in sulfur and sulfur dioxide. Although the surface temperature is -130 degrees, it is possible to find areas around the volcanoes whose temperature exceeds 1000 degrees.
Even though all this evidence is quite discouraging to believe that Io might host a form of life, scientists are more optimistic that that. They think that no matter how hard it can be to come across with any kind of life form on the surface, it is still possible to find life once you go deeper down.
7. Ceres
Ceres, which is located in the asteroid belt between the orbits of Mars and Jupiter, is not only famous for its two shining points; but also thought to have a layer or ice or water hundreds of kilometers below the surface. Scientists also argue that is is very well possible that this ice or water layer includes a larger amount of water than the total amount of water on Earth; however there is no certain evidence yet.
The data that the spacecraft Dawn will be able to collect by the end of this year by flying closer to it will help us know more about Ceres.
8. Mimas
With its 396 km diameter, Mimas, which is thought to be the smallest round celestial body, is a moon of Saturn. This moon, whose surface area is smaller than Spain, looks like a Death Star from the Star Wars universe.
Scientists believe that under the surface of Mimas, there is a rock core or a liquid ocean.
9. Triton
Triton, which is one of the moons of Neptune (and also the biggest), rotates in the opposite direction of other big moons in our solar system; which makes it the only moon out among 13 others that doesn't rotate in the direction of the planet itself. Scientist think that Triton used to be a celestial body in the Kuiper Belt, but then later on got caught in the gravitation of Neptune; however, we don't know anything certain.
Just like Pluto, Triton also has a thin atmosphere, which consists of the nitrogen that evaporates from the surface. Scientists argue that there is a possibility that Triton has a big ocean beneath its surface, and if they are right, Triton is at the top of the list of celestial bodies that could have life.
10. Venus
Venus could be the least likely to host any form of life among other candidates. Why? It is incredibly barren, its atmosphere is so thick that it applies 90 times more pressure than that of the Earth and the surface structure is too high (464 °C). It is dire that all the spacecrafts that are sent there melt and break into pieces in couple of hours, as they can't take the pressure of the thick atmosphere and the high temperatures.
Considering all of the above, it seems wise to ask 'How could we then expect to find life in Venus?'. Some scientists believe that there could be life in the outer layers of its atmosphere: life in the clouds! The reason why is simple: the higher you go, the more suitable the conditions become to host a from of life.
11. Mars
And last but not least: Mars. It is now a very well known fact that there could be life on Mars. The announcement about the salty water streams that we have recently heard is another sign that we are now one step closer to finding life on Mars!
Considering its rivals, Mars is clearly very high up in the list of possible candidates to host life. As Mars is the second most studied celestial body after the Moon, is also very likely to be the first place where we will find extra terrestrial life, assuming that there is indeed a form of life there.
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