Life in Our Solar System
Man has often wondered if life exists on other planets in our solar system, and if so what kind of life? Up until the 20th century it was thought every planet could harbour life, even more advanced than ourselves. You just have to point to the Orson Wells radio broadcast in the 1930’s where widespread panic was caused by a theatre production of “War of the Worlds”, which listeners mistakenly thought was real. This was an indication of how much this belief was held in the common psyche.
Nowadays we know this is just fantasy and that we’re not under imminent attack from little green men from Mars. So is there life anywhere in the solar system apart from Earth and who are the suspects? Well you may be surprised to learn that there are several candidates in our varied solar system.
Let’s start with Mars, the planet that captures our imagination the most. Even though we knew there were no canals on Mars or advanced civilisations scientists involved in the Viking lunar landings in the 1970’s still expected to find something. Viking 1 landed on the Martian surface in June 1976 but unfortunately found nothing. Subsequent missions have also found no sign of life but there’s still hope and it lies underground. The reason for this theory is that methane is present in the Martian atmosphere and one way methane can be produced is biologically. In the warmer summer months on Mars the presence of methane increases dramatically giving more credence to the idea that there are organisms living under the surface.
There are two intriguing moons around Saturn which could maybe support life. Both are very different from one another, they are called Enceladus and Titan. Enceladus is a very small icy world with an area only slightly larger than Texas. Under its surface though there is believed to be a salt water ocean. How can there be an ocean on such an icy world you may ask? Well the tremendous gravitational force of Saturn pushes and pulls the small moon heating up its interior and melting the ice underneath its surface. If so this could provide an environment for micro-organisms or some other forms of life to exist.
Enceladus’s near neighbour, well 600,000 miles away, is another of Saturn’s moons, Titan. This moon is exceptional in the solar system as it is the only one with a significant atmosphere. What’s even more surprising is that its atmosphere is comprised mainly of nitrogen, just like our own. Even more amazing is that it is the only object in our solar system apart from Earth to have large areas of liquid on its surface, not of water but liquid methane. Methane on Titan acts like water on Earth, there are methane clouds which produce methane rain and methane lakes. Titan is often compared to primordial Earth, but unfortunately it’s in deep freeze with surface temperatures around -179C (-290F). Still it is possible that methane based microbial life could exist there breathing hydrogen instead of oxygen, might well be a bit too chilly though.
In my opinion I have left the best till last. It’s an icy moon orbiting around Jupiter called Europa. Scientists believe this moon, just slightly smaller than our own moon, presents the best possibilities for life in the entire solar system. The force of Jupiter’s gravity produces tremendous tidal heating inside Europa warming its interior and producing a salt water ocean which is 62 miles (100 km) deep. It is possible that there is twice the amount of liquid water on Europa than there is on Earth! It has been speculated that Europa’s ocean could be teeming with life, not just bacteria but complex organisms could be swimming in the warm water. Unfortunately we won’t find out until around 2025 when NASA hopes to land a probe on its surface which will then melt through the ice and investigate the ocean for signs of life. Maybe then we will found out that we are not alone.
