Tuesday at the European Week of Astronomy and Space Science meeting in Hatfield, England, astronomers announced a new milestone: an extrasolar planet with the lowest confirmed mass of any yet discovered around a normal star.
“Confirmed” . . . “normal star” . . . seems like a lot of caveats, doesn’t it? Let me explain.
The planet is called Gliese 581 e, and the research says it contains 1.9 times Earth’s mass. Earth-mass planets are the holy grails of extrasolar studies right now. That’s because planets about the size and (rocky) composition of Earth — assuming the right surface conditions and the presence of liquid water — could potentially give rise to life in a form that would be familiar to us. You know, biological bug-eyed monster-type thingies. Or at least a brightly colored slime mold or bacterial colony.
The caveats gum up the works a bit, but they are essential. For instance, it’s important to include “confirmed,” because there is an unconfirmed contender for the lightweight-earthlike-exoplanet crown: MOA-2007-BLG-192-L b.
This little guy might be a mere 1.4 Earth masses, but that depends on certain assumptions being correct — like estimates of how big the planet’s parent star is. The mass of the star could affect the calculated mass of MOA-2007-BLG-192-L b.
And it’s also important to say “normal star” because smaller and lighter planets exist around decidedly abnormal stars called pulsars. A pulsar is the superdense core of an aged star that spins rapidly, causing energy radiating from hotspots on the star to appear to pulsate as seen from a distance, as if you were watching a faraway lighthouse. One known pulsar, called PSR B1620-26, hosts a planet significantly LESS massive than Earth.
The downside for science writers is that when reporting biggest/smallest/fastest scientific discoveries, those caveats sure get in the way of a snappy headline. But in science, the caveats are everything. Scientists are obsessively precise about their claims. They have to be. It’s what we pay them to do – to be careful.
We struggle every day with how to handle those caveats. We want to describe discoveries in the most simple, direct, and clear way possible. But to be accurate, we have to find ways to sneak in the important caveats without tripping up the reader. It’s hard to do, but never impossible.
My first editor — um, let me qualify that: my first editor at a paying professional science-writing job — assured me that the English language is powerful and flexible enough to solve any problem. You just have to work hard to find that perfect turn of phase, that vivid verb, or that ideal sentence structure that does the job.
But I wonder if she ever had to write about low-mass exoplanets.