For centuries, humanity has gazed at the stars, wondering if there’s another world like ours out there.
That question got a lot more interesting in August when astronomers confirmed the discovery of Proxima b, a potentially habitable exoplanet orbiting Proxima Centauri – the closest star to our Solar System.
At just 4.25 light-years away, Proxima b immediately became the most promising candidate for an Earth-like world.
Early studies hinted that it was rocky and situated in the habitable zone, where liquid water could exist.
Now, new research suggests something even more astonishing: Proxima b might be covered in vast oceans of liquid water, making it a serious contender for hosting alien life.
If that’s true, it would mean our cosmic neighbor isn’t just another lifeless rock—it could be a water world, teeming with the ingredients necessary for life as we know it.
And given its unprecedented proximity, it’s a world we could potentially explore within our lifetime.
A Game-Changing Discovery
Before Proxima b’s discovery, the closest known potentially habitable exoplanet was Wolf 1061c, located 14 light-years away—a staggering 126 trillion kilometers from Earth.
To put that in perspective, traveling there with current technology would take thousands of years.
But with Proxima b just 40 trillion kilometers away, scientists are already brainstorming ways to send spacecraft there within 20 years.
That alone makes Proxima b one of the most exciting discoveries in recent history.
It’s so close that we can actually see two of its neighboring stars—Alpha Centauri A and Alpha Centauri B—in the night sky.
In fact, Alpha Centauri A is the fourth-brightest star visible from Earth.
A Planet Drenched in Water?
Now, a team of scientists from the Marseille Astrophysics Laboratory in France has strengthened the case for Proxima b’s habitability.
Using advanced simulations, they calculated the planet’s size, composition, and surface properties more precisely than ever before.
Their findings? Proxima b might be entirely covered in liquid water, making it a true “ocean planet”—similar to some of the icy moons orbiting Jupiter and Saturn.
“The planet could be an ‘ocean planet’, with an ocean covering its entire surface, similar to some icy moons around Jupiter or Saturn,” the team explains.
But Isn’t It Too Close to Its Star?
One of the biggest concerns about Proxima b’s habitability is its extreme proximity to Proxima Centauri.
The planet orbits at just 7.4 million km (4.6 million miles) from its star—a tenth of the distance between Mercury and the Sun.
That might sound like a death sentence.
After all, Mercury—our Solar System’s closest planet to the Sun—boils at 427°C (801°F) during the day and plunges to -173°C (-279°F) at night. Not exactly prime real estate for life.
However, Proxima Centauri is not like our Sun. It’s a red dwarf, meaning it’s only 0.1% as bright and has just 12% of the Sun’s mass.
Because of this, its habitable zone is 25 times closer than the Sun’s.
Even so, some scientists feared that Proxima b might be too hot to support liquid water. But this new study suggests otherwise.
Proxima b Might Be Just Right
Using simulations based on its estimated size and density, the French team determined that Proxima b’s radius is likely between 0.94 and 1.4 times that of Earth.
- If Proxima b is on the smaller end of that estimate (5,990 km radius), it’s likely a dense planet with a metallic core making up two-thirds of its mass, surrounded by a rocky mantle. If it has water, it would likely make up no more than 0.05% of its mass—very similar to Earth.
- If it’s on the larger end (8,920 km radius), things get interesting. The researchers estimate that half of its mass could be water, forming a planet-wide ocean 200 km deep.
And the most exciting part? The simulations suggest that Proxima b has a thin, gassy atmosphere—crucial for regulating temperature and sustaining life.
“Contrary to what one might expect, such proximity does not necessarily mean that Proxima b’s surface is too hot for water to exist in liquid form,” the team reports.
So What’s Next?
Right now, these are still educated guesses.
We won’t know for sure whether Proxima b is a true ocean planet until we send spacecraft to investigate.
Luckily, that might not be as far-fetched as it sounds.
Billionaire Yuri Milner is already funding Breakthrough Starshot, a project aimed at sending laser-propelled nanocraft to Proxima Centauri within 20 years.
Meanwhile, NASA’s James Webb Space Telescope (JWST)—which is finally launching soon—could analyze Proxima b’s atmosphere from Earth by examining the way its light filters through Proxima Centauri’s glow.
The Bottom Line
If Proxima b does indeed have vast oceans, it raises one of the biggest questions in science: Could life exist there?
Water is the single most crucial ingredient for life as we know it, and where there’s water, there’s potential for biology.
While we can’t jump to conclusions just yet, one thing is clear: Proxima b is the most intriguing exoplanet we’ve ever found.
And it’s so close that in the coming decades, we might finally have an answer to the question that has haunted humanity for generations: Are we alone in the universe?
