About 61.6 light-years away — one light-year is the distance light travels in a whole year — a small planet circles a dim star in less time than most school holidays last. That planet is TOI-6716 b, discovered in 2026. The way astronomers found it is a beautiful piece of detective work, and it starts with watching a star’s light very carefully.
What Is TOI-6716 b?
TOI-6716 b is a rocky world that sits remarkably close in size to Earth. Its radius — the distance from its center to its surface — is about 0.98 times Earth’s radius. Its mass, meaning how much matter it contains, is about 0.91 times Earth’s mass. Those numbers make it one of the more Earth-sized planets scientists have measured.
Its likely surface temperature is around 369 K, which works out to about 96 degrees Celsius. That is close to the boiling point of water, so the surface would be quite hot by our standards. Scientists haven’t confirmed whether TOI-6716 b has an atmosphere, and without knowing that, we can’t say for certain what conditions are really like on the ground. An atmosphere could trap heat or reflect it — we simply don’t know yet.
One year on TOI-6716 b lasts just 4.72 Earth days. It orbits its star much faster than Earth orbits the Sun, which tells us it is much closer to its star than we are to ours. So far, it is the only planet scientists have found in this system.
Its Quiet, Cool Star
The star TOI-6716 is what astronomers call a red dwarf — a star that is smaller, dimmer, and cooler than our Sun. Its surface temperature is about 3,110 K. For comparison, our Sun’s surface sits at around 5,778 K, so TOI-6716 is significantly cooler.
Red dwarfs are the most common type of star in our galaxy. Because they give off less light than the Sun, any planet crossing in front of one causes a relatively noticeable dip in brightness. That makes red dwarfs very useful targets for planet hunters. TOI-6716 is close enough to Earth, at 61.6 light-years, that space telescopes can gather good measurements from it.
Red dwarfs can also be active, sometimes sending out bursts of radiation called flares. Whether TOI-6716 is a calm or active star is something scientists continue to study. The character of the star matters a lot when thinking about what a nearby planet’s environment might be like.
How the Transit Method Works
The transit method is the technique that led to the discovery of TOI-6716 b. A transit is what happens when a planet moves across the face of its star, as seen from Earth. The planet blocks a tiny portion of the star’s light, causing a small but measurable dip in brightness.
Here is how astronomers use that dip, step by step.
- Watch the star. A space telescope stares at a patch of sky and measures how bright each star is, over and over again, thousands of times.
- Spot the dip. If a planet is crossing in front of the star, the brightness drops slightly. The drop is often less than one percent — sometimes far less.
- Wait for it to repeat. A real planet orbits on a regular schedule. If the same dip happens again after the same amount of time, that is a strong sign something is orbiting the star.
- Measure the dip’s depth. A deeper dip means a larger planet. By comparing the dip to the known size of the star, scientists can work out how big the planet is.
- Rule out other explanations. Sometimes a dip is caused by two stars orbiting each other, not a planet. Scientists do extra checks to make sure what they are seeing is real.
This method only works if the planet’s orbit is lined up so that it passes between us and its star. Many planets in the galaxy are probably tilted the wrong way for us to see them transit at all. That means transit surveys find a sample of planets, not all of them.
If you want to see how this works visually, the How We Find Them simulator lets you watch a virtual planet cross its star and see the light curve change in real time.
What the Numbers Tell Us
When scientists know both the radius and the mass of a planet, they can calculate its density — how tightly packed its material is. TOI-6716 b’s radius and mass are both slightly below Earth’s, which hints at a rocky composition similar to our planet. Scientists think it is probably not a gas-dominated world, though confirming the internal structure takes more work.
The likely temperature of 369 K is an estimate based on how much light the star gives off and how close the planet orbits. This is called the equilibrium temperature. It assumes the planet reflects a certain amount of starlight and has no atmosphere altering things. The real surface temperature could be higher or lower depending on factors we haven’t measured yet.
TOI-6716 b sits much closer to its star than Earth does to the Sun. At that distance, and with a surface temperature near boiling, it does not sit in the region called the habitable zone — the range of distances where liquid water could potentially exist on a planet’s surface. That doesn’t make it uninteresting. Understanding hot, rocky worlds helps scientists build a fuller picture of how planets of all kinds form and behave.
The Wobble Method: A Second Tool
While the transit method measures a planet’s size, astronomers often use a second technique to find its mass. This is called the radial velocity method, and it works by detecting a tiny wobble in the star itself.
A planet’s gravity tugs on its star as it orbits. That tug makes the star rock back and forth ever so slightly. When the star moves toward us, its light shifts to slightly shorter wavelengths — a change called a blueshift. When it moves away, the light shifts to longer wavelengths, called a redshift. These tiny shifts in color let scientists measure the star’s motion and work backward to estimate the planet’s mass.
For TOI-6716 b, the mass of 0.91 times Earth is a measurement scientists have been able to make. That is a precise result for such a small planet, and it takes very sensitive instruments to pull off.
Why Short Orbits Help Astronomers
TOI-6716 b completes one orbit every 4.72 Earth days. That rapid pace is genuinely useful for planet hunters. The more times a planet transits its star during a telescope’s observation window, the more data astronomers collect. A planet that orbits in under five days can transit dozens of times in just a few months.
Short-period planets are therefore easier to confirm than ones with long orbits. A planet with a year as long as Earth’s would only transit once per year, making it much harder to gather enough data to be sure of the discovery. Many of the planets found by space telescopes so far have short orbital periods for exactly this reason.
TOI-6716 b is a fine example of what modern planet-finding can achieve — a world close to Earth in size, measured carefully from 61.6 light-years away, found by watching the gentle flicker of a distant star.