on Earth doesn't get energy from the Sun?
In 1977 an amazing mini-volcano was discovered deep
in the ocean and since then many more have been
found. Officially known as hydrothermal vents, these
features blast hot (around 300 °C), black water
into the ocean. Because of their colour they are also
known as 'black smokers'.
Even more surprising than the vents themselves
was the fact that a whole colony of creatures was
living around them. These plants and animals, like
the tube worms in the picture, were thriving where
no sunlight had ever reached; they must have another way of deriving energy from their surroundings.
Instead of using sunlight in the photosynthesis
process, these forms of life transfer the energy
they need from the chemicals in the vent water in
a process known as chemosynthesis.
What is really exciting about the discovery of these forms of life is that it shows that planets with warm surfaces and thick, protective atmospheres may not always be necessary for life to evolve. That opens the possibility that life might have evolved on many other planets - planets that we had previously thought unsuitable.