Astronomers have launched an ambitious program to explore one of the strangest regions of exoplanet space: the so-called Neptunian Desert.
Here, planets the size of Neptune are mysteriously rare, while just beyond this region — in what scientists call the “savanna” and the “ridge” — they suddenly become much more common.

To solve this puzzle, researchers created the ATREIDES program, using Europe’s most powerful telescopes and the ultra-precise ESPRESSO spectrograph. Their first target? The planetary system TOI-421.

This system contains two worlds: a smaller inner planet, TOI-421 b, and a hot Neptune, TOI-421 c. But here’s the surprise — their orbits are highly misaligned with the star’s equator.
That’s very different from our solar system, where all planets orbit neatly around the Sun’s equatorial plane.

This tilted architecture suggests a violent past: instead of forming and migrating smoothly, these planets may have been scattered into place by chaotic gravitational interactions.

The results are just the beginning. By mapping many more exo-Neptunes across the desert, savanna, and ridge, astronomers hope to uncover the hidden rules of planetary formation — and perhaps discover new surprises that will force us to rewrite the story of how worlds are made.