In 2026, astronomers added a new name to the growing list of worlds beyond our solar system: TOI-201 d. It is a super-Earth — a planet bigger and heavier than our own — and it sits about 371 light-years away. Learning about worlds like this one helps scientists piece together how planets form and what kinds of places exist across the galaxy.
Where Is TOI-201 d?
TOI-201 d orbits a star called TOI-201. That star is 371 light-years from Earth. A light-year is the distance light travels in one year — about 9.5 trillion kilometres. So 371 light-years is an almost unimaginable distance, far beyond anything a spacecraft could reach in a human lifetime.
TOI-201 is a star that is somewhat similar to our Sun, though it runs a little hotter. Its surface temperature is 6,423 K — that is degrees on the Kelvin scale, which scientists use to measure very high temperatures. Our Sun’s surface sits at around 5,778 K, so TOI-201 is a bit warmer and likely a bit brighter. That extra heat matters a great deal for any planet orbiting close to it.
TOI-201 d is one of at least three known planets in this system. You can explore other confirmed worlds from across the galaxy in the Atlas.
What Kind of World Is TOI-201 d?
TOI-201 d belongs to a group called super-Earths. A super-Earth is simply a planet that is larger and more massive than Earth but smaller than the giant ice worlds like Neptune. The name does not mean the planet is Earth-like — it is just about size.
TOI-201 d has a radius of 1.39 times Earth’s. Picture Earth, then imagine a world roughly 40 percent wider. That is a noticeable step up in size, though not enormous compared to some exoplanets. Scientists have also measured its mass at 5.8 times Earth’s. That means it is considerably heavier for its size.
When you know both the size and the mass of a planet, you can work out its density — how tightly packed its material is. A planet that is small but very heavy is probably made mostly of rock or metal. One that is large but light is likely wrapped in thick gases. TOI-201 d sits in an interesting middle range. Scientists think it may have a rocky interior, possibly with some heavier material at its core, but they have not yet confirmed exactly what it is made of. More observations would be needed to say for certain.
A Blazing Hot Orbit
One of the most striking things about TOI-201 d is how hot it is. Its estimated surface temperature is about 1,237 K — roughly 964 degrees Celsius. That is far hotter than any oven, hotter than molten lava, and well above the melting point of most common rocks. As far as scientists can tell, this is not a place where life as we know it could survive.
The reason for all that heat is simple: TOI-201 d orbits extremely close to its star. One full orbit — what we would call a year on that world — takes only 5.85 Earth days. Compare that to Earth’s 365-day year. A planet racing around its star that quickly must be very nearby, and being that close means it is constantly bathed in intense starlight and heat.
The temperature figure scientists have calculated is called an equilibrium temperature. This is an estimate of how hot the planet should be based on the starlight it receives, assuming no atmosphere. If TOI-201 d does have an atmosphere — and scientists haven’t confirmed whether it does — the real temperature at the surface could be different, possibly higher if gases trap heat the way they do on Venus.
How Scientists Found It
TOI-201 d was discovered in 2026 using a technique called the transit method. When a planet passes in front of its star as seen from Earth, it blocks a tiny fraction of the star’s light. Sensitive telescopes can detect that small dip in brightness. By watching how often the dip repeats, scientists can work out how long the planet’s orbit is. By measuring how deep the dip is, they can estimate the planet’s size.
The transit method is one of the most successful tools astronomers have for finding planets around distant stars. It works best for planets that orbit close to their star — which is exactly the kind of planet TOI-201 d is. A short, tight orbit means transits happen often and are easier to detect and confirm.
The TOI-201 System as a Whole
TOI-201 d is the third known planet in its system. As of 2026, astronomers have confirmed three worlds orbiting TOI-201. The other two planets in the system have their own characteristics, though the details of what they are like have not all been measured yet. It is worth noting that many multi-planet systems discovered so far have even more planets that haven’t been found — smaller or more distant worlds that simply haven’t shown themselves clearly in the data yet.
Each new world added to a known system helps scientists understand how that system formed and evolved. Did the planets grow where they are now, or did they slowly drift inward over millions of years? Questions like these are still being worked out. You can follow the story of how our knowledge of exoplanets has grown on the Discovery Timeline.
TOI-201 d is not a soft, quiet world like Earth. It is hot, dense, and fast-moving — a place that challenges what we think a planet can be. And that, quietly, is what makes it worth knowing about.