Star with planets

K2-18

Also EPIC 201912552

A red dwarf whose planet K2-18 b, a sub-Neptune in the habitable zone, has been studied by JWST.

Measured

124 light-years. To cross it:

Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.

K2-18 b is about 8.9 times Earth's mass per the NASA Exoplanet Archive as of October 2026 (other measurements go down to 7.2), and orbits in its star's habitable zone.
JWST detected methane in 2023 and also reported carbon dioxide. A 2025 reanalysis confirmed the methane but not the CO2; a 2025 preprint on newer JWST data detects both.
Claims of a possible biosignature gas there are disputed and unconfirmed.

Gaia DR3 parallax 26.2469 ± 0.0266 mas, Gaia DR3 3910747531814692736 (Gaia Collaboration 2023, A&A 674, A1)

Every catalogue Ouranos draws is credited on the credits page.

Star with planets

Also EPIC 201912552

A red dwarf whose planet K2-18 b, a sub-Neptune in the habitable zone, has been studied by JWST.

124 light-years. To cross it:

Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.

K2-18 b is about 8.9 times Earth's mass per the NASA Exoplanet Archive as of October 2026 (other measurements go down to 7.2), and orbits in its star's habitable zone.
JWST detected methane in 2023 and also reported carbon dioxide. A 2025 reanalysis confirmed the methane but not the CO2; a 2025 preprint on newer JWST data detects both.
Claims of a possible biosignature gas there are disputed and unconfirmed.

Gaia DR3 parallax 26.2469 ± 0.0266 mas, Gaia DR3 3910747531814692736 (Gaia Collaboration 2023, A&A 674, A1)

Every catalogue Ouranos draws is credited on the credits page.