Are We Too Focused on the Goldilocks Zone?

Image (Credit): Saturn’s moon Enceladus. (NASA)

Astronomers peering into the night sky always talk about exoplanets located in the “Goldilocks Zone,” or “Habitable Zone,” similar to the Earth’s location from the sun. But what if that is too limited? What if we should also be focusing on colder regions as well as exomoons?

The new study released this week based on data from NASA’s spacecraft Cassini has found that Saturn’s moon Enceladus contains the ingredients for life as we know it. The study states:

Saturn’s moon Enceladus harbours a global ice-covered water ocean. The Cassini spacecraft investigated the composition of the ocean by analysis of material ejected into space by the moon’s cryovolcanic plume. The analysis of salt-rich ice grains by Cassini’s Cosmic Dust Analyzer enabled inference of major solutes in the ocean water (Na+, K+, Cl, HCO3, CO32–) and its alkaline pH. Phosphorus, the least abundant of the bio-essential elements, has not yet been detected in an ocean beyond Earth. Earlier geochemical modelling studies suggest that phosphate might be scarce in the ocean of Enceladus and other icy ocean worlds. However, more recent modelling of mineral solubilities in Enceladus’s ocean indicates that phosphate could be relatively abundant.

Again, this represents the building blocks of life and it is the first time all these ingredients have been discovered in our solar system outside of Earth. We did not find it on Venus or Mars, two other planets in the Goldilocks Zone. No, it was found in a much colder part of the solar system on a tiny moon.

This discovery certainly mixes up the situation and provides a much broader region for life to appear in other solar systems. It’s not a new idea, but it has more credibility now that we know a little more about our own neighborhood.

Maybe Goldilock’s concerns about something being too cold was not such a problem after all.

Note: It seems James Cameron figured this out years ago. The planet visited in the Avatar movies, Pandora, is portrayed as a moon (or exomoon) in the Alpha Centauri System.

Image (Credit): Pandora and its host  gas giant Polyphemus from the movie Avatar. (20th Century Fox)