Can we stop calling exoplanets ‘Earth-like,’ please?
Claiming an exoplanet to be “Earth-like” is a trend that needs to bite the dust
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From what I can gather, Freddie Mercury—the rightfully celebrated lead singer of Queen—was about the same height as I am.
So while I’m certainly not Freddie Mercury’s twin, would you say I’m Freddie Mercury–like? Besides having our heights in common, I also am male, have facial hair and can carry a tune (though at that, I am not a champion). Weirdly, we both also worked with rock stars named Brian with Ph.D.s. related to physics, too.
You might argue that, if you squint really hard, I am at best extremely vaguely Freddie Mercury–ish. Really, all you can say is that I’m Freddie Mercury–sized—I certainly wouldn’t go so far as to say Freddie Mercury–like.
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That’s why, among many other reasons, I need not worry about ever being described that way by the media. But then again, I’m not an exoplanet.
To date, astronomers have found more than 6,300 of these alien worlds orbiting other stars, with new entrants to our exoplanetary catalogs arriving practically every day.
Many of these are so weird that they’re difficult to imagine. The very first ones discovered were radiation-riddled worlds orbiting a pulsar—the burned-out stellar remnant of a catastrophic supernova explosion and pretty much the last place anyone would have expected a planet to hide. Next, astronomers spied several exoplanets that are gas giants like Jupiter—but in orbits so tight that these worlds practically skim the surfaces of their stars. Others orbit so far out that it’s hard to explain how they got there. Some exoplanets are rocky but so hot that their surfaces are molten; others are so cold that they’re frozen solid.
Each and every one we find isn’t just a world—it’s an additional data point in the grand scientific quest to understand how planets form and how they change over time, putting our own solar system into context with the rest of the galaxy.
There’s an emotional, almost personal aspect of this, too, because the story of planets is also the story of life’s origins—including our own. And the element of this that calls out to us is the search for another world like Earth.
Just finding a single true twin to our planet would be a huge landmark in science, putting a framework around our very existence. It’s clear the public feels this way, too. The media certainly does: any time an exoplanet pops up with any sort of vaguely familiar terrestrial characteristic, press conferences are held, news stories are written and headlines speculate on what that world may actually be like.
And here we run into a problem: the adjective “Earth-like.” It gets used frequently to describe exoplanets we’ve discovered, but in my opinion, it has never been true.
While the term has been around a long time, it started getting used to describe actual exoplanets once technologies and methods for the search for distant worlds improved, which allowed for smaller, harder-to-see planets to be found. Eventually, astronomers uncovered ones with dimensions similar to Earth’s, and these were sometimes dubbed Earth-like worlds.
Source: Read the original article on www.scientificamerican.com
