Bit of a joke there. What the paper is about is, we found a new planet, about 18.2 light years away. That means that we’re seeing the planet as it appeared 18.2 years ago, in the summer of 2007.
Summer 2007: the first iPhone had just hit the market, the last Harry Potter book was fresh on the bookshops, Rihanna’s “Umbrella” was all over the radio, and “The Big Bang Theory” was about to premiere on TV. Britain’s Tony Blair had just handed off to Gordon Brown, while in the US a freshman Senator named Barack Obama was quietly preparing his Presidential bid. And the world economy was sliding inexorably towards the Great Recession.
Anyway, the planet. The planet is a “Super-Earth“. That means it’s basically the same sort of planet as Earth: a ball of rock, probably with an iron core, possibly with an atmosphere. But it’s bigger than Earth, hence the “Super”. Like, if the Earth was a golf ball, this planet would be more like a cricket ball or a baseball. Definitely bigger, but not so much bigger that it’s a different sort of thing.
Okay, so we’ve found lots of planets around other stars. Like, literally thousands of them. And we’re finding more new planets every day. So what’s interesting about this one?
[this shows something like one quarter of the currently known planets. and yes, that lower right one is not a proper sphere.]
Well… maybe a couple of things. But first, a brief digression!
Earth’s atmosphere is about 20% oxygen. And oxygen, as we all learned in grade school, is produced by plants.
[kid was obviously not expecting this]
So the oxygen in Earth’s atmosphere is “biogenic”: created by life. So if we detect oxygen in the atmosphere of an alien planet, would that be evidence of life?
Turns out the answer is not “of course yes”! Right now it seems to be somewhere between “maybe” and “probably”. Apparently there are hypothetical scenarios that could maybe, perhaps, put a lot of oxygen into a planet’s atmosphere through geological and astronomical processes, without life being involved. In this case the oxygen would be “abiogenic”. So finding oxygen would be suggestive, but — given the current state of the art — not definitive.
But! Earth’s atmosphere also contains a little bit of methane. Methane is produced naturally by certain sorts of bacteria. Some of these bacteria live in the guts of large land animals. This is why your burps and farts contain a little bit of methane. (Cows have a lot more of these bacteria, so their burps and farts contain a lot more methane.) For various reasons, planet Earth has a lot more plants than it has methane-producing bacteria. And this is good, because it means Earth’s atmosphere contains lots of oxygen but only a faint wisp of methane. If it was the other way around, we wouldn’t like it very much.
[strictly speaking the burps produce more, but well]
Here’s where it gets interesting: methane and oxygen do not get along. If there’s even a little oxygen around, then methane breaks down pretty quickly. The average life expectancy of a methane molecule in Earth’s atmosphere? It’s about 10 years. If all methane production stopped tomorrow, within a century or so that wisp of methane would disappear completely.
So while oxygen alone may not be a conclusive sign of life, oxygen and methane combined… as best we can tell, that’s pretty much a lock. Nobody can think of a way to get those two gases into an atmosphere together, at the same time, without resorting to biology. Finding oxygen in a planet’s atmosphere would be suggestive. Finding oxygen plus methane — or any other combination of gases that aren’t chemically compatible — would be definitive. 
It would be what astronomers are calling a “biosignature”.
We haven’t found any biosignatures yet. But then, we haven’t been looking very long. The first discovery of an exoplanet around another star was in 1995. That’s just thirty years ago!
[Top grossing movies of 1995. I will admit to seeing like two of these in the theater]
In 1990 you could stand up and say “There’s literally zero evidence for planets outside the Solar System. So far as we know, the Sun’s nine planets are all the planets that exist.” And that would have been an intellectually defensible, philosophically valid statement. In fact, there were perfectly respectable thinkers who came out with milder versions of this. We just didn’t know.
As a result, up until the 1990s it wasn’t really possible to have a meaningful discussion about life in the Universe outside the Solar System. I mean, obviously people did talk about it — Sagan and Shlovskii wrote a long book about it, I used to have it on my shelf — but it was all speculation. We just didn’t have enough facts to discuss the topic seriously.
Okay, so now we have some facts. Most obviously, we know that planets are pretty common. We’re getting some ideas of how planets form, what categories there are, what sorts of atmospheres are possible. Our data pool is badly biased, because our current planet-finding techniques skew strongly towards finding large planets, hot planets, and planets around small stars — but we recognize the bias, and it’s an actual no-kidding data pool.
At some point in the future, we’ll have a pretty good conclusion about life outside the Solar System. Either we’ll detect a strong, unambiguous biosignature — something like the oxygen / methane combination — or we’ll amass such a towering pile of negative results that “no life” becomes, if not a certainty, a very strong and reasonable conclusion. 
[copyright Jorge Cham, phdcomics 2009]
How far off is that future time? Probably less than a century. I would guess that by 2100 — 75 years from now — there will be a fairly strong consensus one way or the other, and the question will be considered pretty well settled. You can of course argue with that particular estimate. But the general point is obviously valid: at some point in the future, a time will come when the question is pretty clearly settled.
What that means is that now, right now, we’re in a very special time. It’s a time when we’re actively looking for life out there — The Search is underway — but the question is still open.
For all of human history until the 1990s we couldn’t do anything but speculate. And at some point in the future — I suspect around 2100, but it could be 2150 or 2200 or 1500, whatever — we’ll know, or anyway we’ll be pretty sure we know. Right now is the only time in history when we’re able to actually Look, but we haven’t yet Found. This brief period is epistemologically unique. We are living through the short-lived Age Of The Search. And when it’s over, one way or another, it will be over forever.
Phew. Okay, so this one particular planet. Turns out The Search breaks down fractally into lots of smaller questions. And right now, at this particular stage of things, one open unanswered question is: can red dwarf stars have habitable planets around them?
Red dwarf stars are small, dim, red stars. They’re smaller and cooler than our Sun, and much dimmer. And they’re by far the most common sort of star! About three quarters of all stars are red dwarfs.
If red dwarf stars can’t have habitable planets, then The Search abruptly narrows by quite a lot. Basically that leaves the medium sized stars: the K, G and F types, orange and yellow and white. That’s less than a quarter of the total. (The big blue B and O types are probably too short lived to allow life to form — they burn hot and fast, and blow up after just a few million years.) So if life needs habitable planets
The Red Dwarf Question is, itself, fractally complicated. I’m going to blow past a bunch of stuff and just focus on one issue: solar flares. Despite being generally cool and dim, most red dwarf stars go through a period of producing truly massive solar flares. Like, far bigger and worse than anything our Sun has ever done. Usually this period is when the star is young, and then after a while they grow out of it. In some cases older red dwarfs can still keep it going. As I said, fractally complicated.
Now as far as we know, life requires liquid water. Yes, that “as far as we know” is doing a lot of work! Maybe the universe is full of super-cold life that lives in liquid methane, or super-hot life that swims around in oceans of lava. But the first place we’re going to look for life is where there’s liquid water, because we know life is possible there. And that means in the “habitable zone” — the region around a star where it’s neither too cold nor too hot.
Okay, so: because red dwarfs are so dim and cool, the habitable zone around a red dwarf is very close to the star. Which raises some issues. One big issue is, if you’re that close to your star, then a solar flare can erode your atmosphere. And if your star continues to flare regularly? Then over millions of years, it can erode your atmosphere right out of existence, leaving your planet a dead, airless rock.
[copyright HapNStance, Reddit, 2022]
So “will red dwarfs destroy the atmospheres of planets in their habitable zones?” is a subset of the Red Dwarf Question, which is itself a subset of the Life Question.
And we are actively working on it! We’re looking for planets in the habitable zones of red dwarf stars — which is a bit of a challenge, because reasons, but we’re working on it — and when we find them, we’re staring hard at them looking for atmospheres. It’s early days, but we’re making progress.
Which loops us back around to that Super-Earth, which currently bears the euphonious designation of “GJ 251 c”. This planet is interesting because (1) it’s in the habitable zone of a red dwarf star, and (2) it’s a star that is close to us. I mean, really close to us. By galactic standards, 18.2 light years away is pretty much next door. So GJ 251 c is, as the paper puts it, “amenable to direct imaging”. That means it’s close enough that the next generation of telescopes, coming online in the early 2030s, will be able to see the planet directly. And they’ll be able to measure whether it has an atmosphere, and if so, of what sort.
Which will bring us closer to answering the Red Dwarf Planet Atmosphere Question, which will move us forward on the Red Dwarf Question, which will probably be a big part of the Life Question.
And then one day we’ll know.
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