Our planet’s biosphere has all the known ingredients necessary for existence as we know it. These are liquid water, one source of energy, and a wide range of biologically useful molecules and elements. However, the recent discovery of potentially biogenic phosphine in Venus’ clouds reminds us that some of these factors exist elsewhere, too.
Titan is Saturn’s biggest moon. It’s also the only moon in our solar system with an atmosphere. It has a thick orange haze of organic molecules, as well as a methane weather system. The planet has seasonal rains, surface sand dunes, and dry periods. Its atmosphere is composed mostly of Nitrogen, a crucial chemical element used in protein construction in all forms of life.
Moreover, radar observations have discovered the presence of lakes and rivers of liquid ethane and methane. There was also the possibility of cryovolcanoes and volcano-like features that deliver liquid water, not lava. This conveys the idea that Titan, similar to Enceladus and Europa, has a reserve of liquid water.
In the entire solar system, Mars is the most Earth-like. It has contracts with the seasons, polar ice caps, and a 24.5-hour day. Furthermore, there is a wide range of features that were sculpted by water during Mars’ history.
The exploration of methane in its atmosphere and a lake beneath its southern polar ice cap makes it an amazing candidate for life. Methane is important as it can be created by biological processes. However, the actual source for Mars methane is not yet known.
Today, Mars has a dry, thin atmosphere composed mostly of carbon dioxide. This provides scant protection from cosmic and solar radiation. If the red planet has managed to retain water reserves beneath its surface, it’s not impossible that some form of life may still exist.
Europa was discovered by Galileo Galilei back in 1610, along with Jupiter’s 3 other bigger moons. It’s a bit smaller than our moon, and it orbits Jupiter at a distance of around 670,000 km once every 3.5 days. Europa is stretched and squeezed constantly by the gravitational fields of Jupiter, as well as the other Galilean moons. This process is also called tidal flexing. Europa is said to be a geologically active world, similar to Earth.
Just like Europa, Enceladus is ice-covered and comes with an ocean of liquid water. It first came to scientists’ attention as a potentially habitable world after the discovery of geysers near its south pole.
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