Confirmed exoplanet · Database record + computed analysis
HAT-P-17 b
A confirmed world orbiting HAT-P-17, 301.3 light-years away.
A gas giant
11.77 Earth radii, Jupiter-class (Jupiter is 11.2). At only 184.3 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 10.3 Earth days. The orbit is strongly stretched (eccentricity 0.35), so its distance from the star, and with it the climate, swings dramatically.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 527 °C. Hotter than Venus's surface. It receives 110.5 times the starlight Earth gets.
Its sun
Its star is an orange K-type (5,246 K), K: cooler and longer-lived than the Sun, a class some astronomers consider ideal for habitability. It shares the system with 1 other known planet.
How far is that, really?
At 301 light-years, tonight's light from this system left it around the year 1724. A Voyager-speed probe would need roughly 5,331,015 years to get there.
How we found it
It was found by the transit method: the planet crosses its star's face on schedule, dimming it by a tiny, repeating fraction. The dip's depth gives the planet's size. The discovery was announced in 2012 from HATNet.
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.