Astronomers have recently identified an exoplanet that stands out from the familiar rocky worlds we know. This planet is larger than Earth, yet appears to be composed in large part of water — possibly even entirely covered by it.
The discovery challenges our assumptions about planetary formation and opens up exciting possibilities about the diversity of worlds in the universe.
How It Was Found
The planet in question, known as TOI‑1452 b, orbits a red dwarf star about 100 light‐years away in the constellation Draco. Scientists detected it by using the transit method: the planet passes in front of its star and causes a slight dimming of the star’s light.
Detailed measurements of its mass and radius then allowed the researchers to infer its average density.
Because its density is lower than would be expected for a purely rocky planet of its size, the team concluded that it must contain a large proportion of water or other low‐density material.
What We Know About the Planet
TOI-1452 b size compared to our planet is about 1.67 times the radius of Earth and roughly five times as massive.
That combination means the planet’s overall density is significantly less than Earth’s, suggesting a large portion of the volume could be made up of water or ice in some form rather than solid rock.
In other words, rather than being a scaled‐up version of Earth (rocky and dry), this world may be a “water‐world” — perhaps with a global ocean covering its surface, or with water in very deep layers beneath a high‐pressure atmosphere.
Why the “Water Worlds” Are Special
For a planet to be largely water, several conditions must align. Its density must be lower than that of purely rocky planets, indicating the presence of lighter constituents.
For TOI-1452 b, the low density is a strong clue. Scientists modelling water‐rich planets find that when you have a “super‐Earth” (larger than Earth) with a low density, you can no longer assume it is simply rock and iron.
It could instead be largely water or a combination of water and ice. In addition, being placed in a region where water can remain in liquid form or at least in stable phase under pressure helps.
Although TOI-1452 b may not meet all the ideal habitable-planet criteria, the fact that water is hypothesized at all is significant: it shows that planetary diversity includes entire worlds dominated by water rather than rock, according to NASA Jet Propulsion Laboratory.
Implications for Planetary Science
The discovery of a likely water‐covered planet has several important implications. First, it broadens the kinds of planets we expect to find.
We might not just find “Earth-twins” (rocky, Earth‐size) but also “Ocean worlds” or “Water worlds” where the surface is not land plus ocean, but perhaps only ocean.
That changes how we think about habitability, geology, atmospheric processes, and internal structure for exoplanets.
Second, such planets force us to refine our models of formation and evolution. How does a planet acquire so much water?
Did it form beyond the so‐called “snow line” (the region of a star system where ice is stable) and migrate inward? Or did it accrete large amounts of water‐rich material early on?
The case of TOI-1452 b suggests that the migration and accumulation models for super-Earths must allow for large water fractions.
Third, for the search for life beyond Earth, water worlds are intriguing. Liquid water is a key ingredient for life as we know it.
A planet like TOI-1452 b invites questions: Could life exist beneath a vast global ocean? What kind of internal heating and chemical cycling might be required? While we are far from answering these, the existence of such a world widens the canvas of possible habitats.
What We Still Don’t Know
Despite the excitement, many uncertainties remain. Because the planet is so far away and faint, direct imaging remains impossible for now.
We lack detailed atmospheric data: we don’t yet know the composition of any atmosphere it might have, the surface conditions, or the exact state of its water (liquid, ice, high‐pressure forms).
Also, although the density suggests a lot of water, “entirely covered” is still a hypothesis rather than a confirmed fact.
Furthermore, even if water dominates, we don’t know how deep the ocean might be, whether there is a rocky core beneath, or whether high pressures lead to exotic phases of water (such as supercritical fluid or high‐pressure ice).
Some models show that on very water‐rich planets, the “ocean” might be hundreds of kilometers deep, or the surface might be steam or super‐critical under extreme conditions.
