We point of telescopes at distant solar systems searching for exoplanets in the “Goldilocks Zone,” it being defined as the habitable zone around a star where water can remain in liquid form. But that was not always the case for planet Earth, even if we are the model for this zone.
A recent New York Times article, “How Earth Might Have Turned Into a Snowball,” discusses how the Earth became a frozen ball about 717 million years ago. And it remained in this deep freeze for approximately 56 million years.
While the article goes on to discuss the reasons for this freeze, I am more interested in the idea of what this may mean for our own plans to someday travel to a distant star.
If a civilization on another planet was viewing our solar system from afar 750 million years ago, they too may have mistaken our Earth as a perfectly place planet to support life on its surface. However, they would have needed to wait another 23 million years for our planet to revert back to having a liquid surface.
It appears timing is everything, and the inner workings of a planet can be just as important as its placement in the solar system. I expect our telescopes will be able to tease our more information about each exoplanet in the future, though it also makes sense to send robotic probes before ever attempting to send a human that far.
In the meantime, we have a few moons here in our own solar system with frozen oceans. We can start to learn more about the potential for life in such places and our ability to survive in such climates. NASA’s Europa Clipper, set to launch later this year, is part of that learning process.
Our Awesome Universe 