The search for Goldilocks planets.
It has long been a theory of astronomers that the exploration of the universe for habitable planets was likened to the Goldilocks story. The star supporting the planet would need to be not too big and not too small so the right amount of heat and radiation would be produced. The planet would need to be close enough to this star to be able to have an ambient temperature in which water would be in its liquid state, but not too far. It would need to be of a similar size to Earth not too big or not too small in order for the effect of gravity to not be too powerful. However, researchers at NASA and Yale University this year have looked at new evidence suggesting that we need to look inside the planets structure not just at the position in space. Scientists looked at the early evolution of our planet; the importance of the internal temperature of the newly formed Earth and the way in which plate tectonics have affected life forming.
The starting temperature of the core of the planet is now thought to be crucial and although this has fluctuated in Earth’s history it has now been relatively stable for the last 3 billion years, the same time frame in which life has evolved. It is also thought to be linked to the formation of the oceans as if it had been too hot inside the earth these would never have occurred.
Plate tectonics provides a mechanism to react like a global thermostat. Most volcanism on the Earth occurs at plate boundaries in response to plate tectonics and mantle dynamics. And the most important volcanic products by mass – by a large amount – are two greenhouse gases: carbon dioxide and water which has created a ‘blanket’ for the biosphere. Plate tectonics also create mountains which are a way of locking up CO2 and therefore regulating its concentration in the atmosphere.
These two factors may be a larger determinant to how life can begin than first expected and would need to be present in a habitable planet.