Exoplanet · super-Earth
TOI-521 b
TOI-521 b is a super-Earth orbiting the star TOI-521. Its year lasts 1.54 Earth days. It was discovered in 2025 by the Transit method.
| Host star | TOI-521 |
|---|---|
| Distance | 198.8 light-years (60.9 pc) |
| Orbital period | 37 hours |
| Orbital radius | 0.0195 AU |
| Eccentricity | 0.000 |
| Radius | 1.98 R⊕ · 0.177 R♃ |
| Mass | 5.3 M⊕ · 0.0167 M♃ |
| Density | 3.8 g/cm³ |
| Surface gravity | 1.35 × Earth |
| Equilibrium temperature | 794 K (521 °C) |
| Stellar flux received | 66 × Earth |
| Discovery method | Transit |
| Discovery year | 2025 |
| Discovered by | Transiting Exoplanet Survey Satellite (TESS) |
Habitable zone
Inside the inner edge of the habitable zone: it receives 66 times the light the Earth does, too hot to keep liquid water on its surface.
Its star in the sky
In the planet's sky its star is a disc 11° across: 22 times the Sun as we see it from Earth.
In the sky
A telescope is needed to see it: its apparent magnitude is 14.64. Visible from the whole Northern Hemisphere and south to latitude 78° S. North of latitude 78° N it never sets. It stands highest at midnight in January, the best time to observe it.
Light's journey
The light you see tonight set out around the year 1827. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 3.5 million years.
Data: NASA Exoplanet Archive, PSCompPars. Its look in the simulation is a rendering based on the measured radius, mass and temperature.