Confirmed exoplanet · Database record + computed analysis
HD 168009 b
A confirmed world orbiting HD 168009, 76.0 light-years away.
A sub-Neptune
3.05 Earth radii, likely a rocky core under a thick gas or steam envelope rather than a walkable surface. At only 9.5 Earth masses for that size, it must be substantially gas or volatile ices: puffy, not rocky.
The orbit
Its year, one full orbit, takes just 15.1 Earth days.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 614 °C. Hotter than Venus's surface. It receives 99.4 times the starlight Earth gets.
Its sun
Its star is Sun-like (5,778 K, G2V; the Sun is 5,772 K).
How far is that, really?
At 76 light-years, tonight's light from this system left it around the year 1949. A Voyager-speed probe would need roughly 1,344,723 years to get there.
How we found it
It was found by the radial-velocity method: the planet's gravity swings its star in a small circle, and that wobble shows up as a rhythmic Doppler shift in the starlight. The wobble's size gives the planet's minimum mass. The discovery was announced in 2021 from Multiple Observatories.
Everything above is computed from the archive’s measured values for this planet. Where a quantity is missing, the statement is omitted rather than guessed.
About this record
The measured values come from the NASA Exoplanet Archive, and any missing value has not been determined yet; the Atlas never fills gaps with guesses. More standout worlds: Proxima b, TRAPPIST-1e, K2-18 b, 55 Cancri e, and the detection methods that found them all.