One of the awesome things about studying space and astronomy is that the science can jump between being really darn pretty and really darn meaningful. Astronomy can answer how did it start and how will it end, and in planetary science, we can look for “where might there be life”. 

Before we found planets, it was good enough to say, “If a planet is in its star’s habitable zone, where water can be liquid, it could have life.” Now that we are finding planets in that place, we’d like to be a bit more specific. Researcher Brendan Dyke and his team have taken inspiration from our own Earth as they look for the answer. It turns out, it all comes down to the iron. 

According to Dyke: Just because a rocky planet can have liquid water doesn’t mean it does. Take a look right in our own solar system. Mars is also within the habitable zone and although it once supported liquid water, it has long since dried up. Our findings show that if we know the amount of iron present in a planet’s mantle, we can predict how thick its crust will be and, in turn, whether liquid water and an atmosphere may be present. It’s a more precise way of identifying potential new Earth-like worlds than relying on their position in the habitable zone alone. 

Measuring the amount of iron in the mantle of a distant planet isn’t something we can do today, but it may be possible in the future. JWST should open the door to exploring the chemistry of alien worlds. Here is to hoping that that much-delayed telescope someday flies and functions.

More Information

UBCO press release

“The effect of core formation on surface composition and planetary habitability,” Brendan Dyck, Jon Wade, and Richard Palin, to be published in The Astrophysical Journal Letters (preprint on arxiv.org)