In 2026, astronomers confirmed a new world orbiting a distant star. That world is called TOI-4363 b, and it belongs to a growing family of planets known as super-Earths — planets bigger than our own but smaller than the ice giants Uranus and Neptune. It is 254 light-years away, which is quite far, yet scientists have already learned a surprising amount about it.
Where in Space Is TOI-4363 b?
TOI-4363 b sits 254 light-years from Earth. A light-year is the distance light travels in one full year — about 9.5 trillion kilometres. So 254 light-years is an enormous distance, far beyond anything any spacecraft has ever reached. Even so, in the grand scale of our galaxy, it is actually a fairly close neighbour. The Milky Way stretches roughly 100,000 light-years across, so TOI-4363 b is practically in our own backyard, astronomically speaking.
You can browse other worlds at similar distances in the Extremetica Atlas, which maps confirmed exoplanets by their distance and type.
How Scientists Found It
TOI-4363 b was discovered using the transit method. Here is what that means: when a planet passes in front of its star, it blocks a tiny fraction of the star’s light. Telescopes watching the star notice a small, regular dip in brightness. By measuring how deep that dip is and how often it repeats, scientists can work out a planet’s size and how long its year is.
The “TOI” in the planet’s name stands for TESS Object of Interest. TESS is a NASA space telescope designed to watch hundreds of thousands of stars for exactly these small flickers of light. When TESS flags a candidate planet, astronomers follow up with other observations to confirm whether the dip is really caused by a planet. That follow-up work is what led to the official confirmation of TOI-4363 b in 2026.
The Extremetica Discovery Timeline shows how techniques like the transit method have transformed our understanding of planets beyond our solar system.
Size and Mass: A Chunky Little World
TOI-4363 b has a radius 1.77 times that of Earth. Picture Earth, then imagine a world about three-quarters wider — that gives you a rough sense of its size. Its mass is 3.77 times Earth’s, meaning it contains nearly four times as much material as our planet.
Knowing both the size and mass of a planet is really useful. Scientists can use those two numbers together to work out a planet’s density — how tightly packed its material is. A rough calculation suggests TOI-4363 b is fairly dense for its size, which hints that it may be a rocky world, perhaps with a thick layer of heavier elements inside. However, scientists are careful about this kind of estimate. Without more detailed measurements, we cannot say for certain what the planet is made of on the inside.
A Very Short, Very Hot Year
One of the most striking things about TOI-4363 b is how fast it travels around its star. One full orbit — what we would call a year on that planet — takes just 2.12 Earth days. That is less than two and a half days for an entire year. To complete an orbit that quickly, the planet must be orbiting very close to its star.
That closeness has a serious consequence: heat. Scientists estimate the planet’s surface temperature is around 885 K, which works out to roughly 612 degrees Celsius. That is far hotter than any oven, hotter even than some lava flows on Earth. At that temperature, many rocks would melt, and any water would exist only as vapour — if it exists at all. TOI-4363 b does not sit in the habitable zone, the range of distances from a star where liquid water could exist on a planet’s surface. It is far too close and far too hot for that.
It is worth noting that the 885 K figure is an estimate. It assumes certain things about how the planet reflects light, and those details have not been directly measured. So while scientists are fairly confident the planet is extremely hot, the exact number could shift as more data comes in.
What Kind of Star Does It Orbit?
TOI-4363 b orbits a star called TOI-4363. The star’s surface temperature is 4,278 K. Our own Sun has a surface temperature of around 5,778 K, so TOI-4363 is noticeably cooler. Cooler stars tend to appear more orange or red rather than the yellow-white of our Sun. A star like this is often called a K-type star or, if it is on the cooler end, an early M-type star — though the exact classification of TOI-4363 has not been listed in our data, so we won’t guess beyond what the temperature tells us.
Cooler, smaller stars are very common in our galaxy, and they are popular targets in the search for planets. TOI-4363 b is so far the only known planet in this system, but that does not mean no others exist. It simply means none have been confirmed yet.
What We Still Don’t Know
There is quite a lot about TOI-4363 b that science hasn’t pinned down. We don’t have a confirmed measurement of its atmosphere — or whether it has one at all. At such high temperatures and in such a close orbit, any light gases might have been stripped away long ago by radiation from the star. Scientists also haven’t measured its exact composition. Whether it has a solid surface, a magma ocean, or something else entirely remains an open question.
TOI-4363 b is a good example of how exoplanet science works: each confirmed planet is a new data point, and most data points raise at least as many questions as they answer. What we do know is that this small, dense, scorching world is a real place, orbiting a real star, 254 light-years away — and that alone is worth pausing to think about.