![KOI-351 b: 8-Planet System, 0.074 AU Out](https://cdn.slatesource.com/a/5/e/a5e9a5fa-543f-4cd7-9644-f8f1826f36e2.webp) # KOI-351 b: 8-Planet System, 0.074 AU Out - [Made in Slatesource](https://slatesource.com/@steph/koi-351-b-8-planet-system-0-074-au-out) - By [Steph](https://slatesource.com/@steph) - Created on Sep 19, 2026 ## Super-earth around KOI-351 It is 1.31 times Earth's radius, closest in size to Earth. A year there lasts 7.01 days, on an orbit 5 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 1080 K (derived from the star rather than measured), hot enough to melt lead. The host star KOI-351 runs at 6080 K with 1.20 times the Sun's mass. journey·5 Planets # KOI-351 from the inside out Orbit / Planet "super-Earth, 1080 K. "terrestrial, 985 K. "mini-Neptune, 519 K. "mini-Neptune, 453 K. "mini-Neptune, 424 K. Radius 1.31 Earth radii Equilibrium temperature 1080 K (derived) One year 7.01 days Orbit radius 0.0740 AU Host star KOI-351 at 6080 K Distance 2767 light-years Starlight blocked 0.010% at each transit What you get from the shadow How deep the star dims fixes the planet's size relative to it. 🔭🪐📅01.01.2013 – 01.01.2017 01.01.2013KOI-351 b, KOI-351 c, KOI-351 d, KOI-351 e, KOI-351 f 01.01.2013 01.01.2017Kepler-90 i 01.01.2017 The state of the record for this planet 0% A radius from transit photometry. Yes. A measured mass. No. A density, the one clue to composition. No. A semi-major axis. Yes. A measured temperature rather than a derived one. No. An eccentricity, so the orbit shape is known. No. The archive lists no measured equilibrium temperature for this planet. The 1080 K quoted here is derived from the star's output and the orbital distance, assuming a third of the light is reflected. It is an estimate from two numbers, not an observation. The detection is a shadow crossing a disc. Shadows have no weight, which is the whole reason the mass column is empty. KOI-351 has 8 known planets. A crowded system is worth more than the sum of its planets: the timing of each transit constrains the others. Found by Kepler in 2013. Kepler's method needed repetition, not brightness. It could find small planets around faint stars, provided they came round quickly enough to be seen twice. # Half the temperatures quoted for exoplanets are calculated from the star, not \\ measured at the planet. Should a page like this show them at all, or leave the field blank? No comments yet. Be the first. Log in to comment [Every parameter ever published for KOI-351 b, at the NASA Exoplanet Archive](https://exoplanetarchive.ipac.caltech.edu/overview/KOI-351%20b?utm_source=slatesource)