We found a 'Mega-Earth' that’s a total rebel—it orbits its star over the poles, top-to-bottom, instead of around the middle like our planets.
March 27, 2026
Original Paper
GJ 523b is a Massive, 170 Myr-old Mega-Earth, Likely on a Polar Orbit
arXiv · 2603.24682
The Takeaway
This planet is a massive rocky world twice the size of Earth but with no gas atmosphere. Even weirder, it orbits at a 71-degree angle, traveling over the 'top' and 'bottom' of its star, which completely defies standard models of how solar systems form from flat disks of dust.
From the abstract
We use WIYN/NEID radial velocity measurements to confirm the planetary nature and measure the mass of the TESS transiting exoplanet candidate around the mid-K dwarf GJ 523 ($V=9.23$, $K=6.525$). We find that GJ 523b is on a 17.75 day orbit and has a radius of $2.55\pm0.15\,R_\oplus$, a mass of $23.5\pm3.3\,M_\oplus$, and a zero-albedo equilibrium temperature of 538 K. GJ 523b's high bulk density of $7.8\pm1.8$ g cm$^{-3}$ and position on a mass-radius diagram implies a surprising low atmospheric