![HR 8799 b: Photographed, Not Inferred](https://cdn.slatesource.com/6/5/1/65171fdc-9b93-48cf-be8d-e27387886c43.webp) # HR 8799 b: Photographed, Not Inferred - [Made in Slatesource](https://slatesource.com/@steph/hr-8799-b-photographed-not-inferred) - By [Steph](https://slatesource.com/@steph) - Created on Sep 19, 2026 ## Gas giant around HR 8799 It is 1.16 times Jupiter's radius, closest in size to Jupiter, and 2000.0 times Earth's mass. A year there lasts 465.4 years, on an orbit 175.7 times Mercury's distance from the Sun. journey·4 Planets # HR 8799 from the inside out Orbit / Planet "gas giant, 1150 K. "gas giant, temperature unknown. "gas giant, temperature unknown. "gas giant, temperature unknown. Radius 13.00 Earth radii Mass 2000.0 Earth masses One year 465.4 years Orbit radius 68.0000 AU Distance 135 light-years 🔭🪐📅01.01.2008 – 01.01.2010 01.01.2008HR 8799 b, HR 8799 c, HR 8799 d 01.01.2008 01.01.2010HR 8799 e 01.01.2010 What the archive holds on this planet 0% A size. Yes. A measured mass. Yes. A density, which decides rock or gas. No. An orbital distance. Yes. A measured temperature rather than a derived one. No. An eccentricity, so we know if the orbit is a circle. No. What a direct image buys you A position, a brightness, and light that can be split into a spectrum. This is one of the rare planets that has actually been photographed. Fewer than a hundred of the thousands known were found this way, and they are mostly young giants far from their stars. HR 8799 has 4 known planets. A crowded system is worth more than the sum of its planets: the timing of each transit constrains the others. Found by Gemini Observatory in 2008. # Fewer than a hundred planets have been photographed rather than inferred. Does \\ seeing one directly change how real it feels to you? No comments yet. Be the first. Log in to comment [NASA Exoplanet Archive: every published measurement of this planet](https://exoplanetarchive.ipac.caltech.edu/overview/HR%208799%20b?utm_source=slatesource)