I was browsing ye olde Wired today and came across an interesting article about planetary classification. Essentially, they’re now classifying planets in two ways, similarity to Earth with the Earth Similarity Index (ESI) and the chances that it might be habitable with the Planetary Habitability Index (PSI).
What the “S” in the PSI stands for, I have no idea. Guess they liked the whole “SI” thing. Anyway, they go on to explain its use as so:
Within our own solar system, for instance, Saturn’s moon Titan is a tiny world where water is only available in frozen chunks hard as rock. But its temperature range makes possible the existence of lakes and rivers of liquid hydrocarbons, leading some researchers to speculate that native life could exist there.
As such, Titan gets a rather low ESI but a more optimistic, middle-range PSI. Mars, in contrast, is closer to Earth in size and composition, giving it a high ESI, but has no known liquid on its surface, placing it lower than Titan on the PSI range.
Fucking fantastic! And it makes tons of sense.
The really neat thing about this is that it opens up the possibility that scientists will begin searching for life that may not have evolved under similar conditions to that of Earth.
What will also be interesting to find out is where scientists might consider planets that are sulfurous on the PSI scale when it comes to possible silicon-based lifeforms. While still only theoretical right now, it’s been floating around in science-fiction circles for so long now, one wonder when it will prove to be true like tricorders, deflector shields, and all the other suff that’s happened in the technology realm.
It seems the question is, when might science-fiction biology prove to be real also?
Photo credit: Wikimedia/Lucianomendez
Correction: It looks like Wired updated the article, so the new Planet Habitability Index logically is named “PHI”. Too bad. I kind of was looking forward to seeing someone justify the acronym.