PDS 70b was the first confirmed protoplanet to be directly imaged. Unlike most exoplanets, which are inferred from stellar wobbles or repeated transits, PDS 70b was observed as a distinct source of light near its young host star.
The planet was imaged in 2018 with the SPHERE instrument on the European Southern Observatory’s Very Large Telescope. It is still embedded in the broad environment where planets are born: PDS 70 is a roughly 5.4-million-year-old T Tauri star surrounded by a protoplanetary disk. PDS 70b orbits at about 20.8 astronomical units and may be several times more massive than Jupiter.
“Protoplanet” describes a planet still forming, rather than a permanent class such as super-Earth or hot Jupiter. PDS 70b is hot—estimated at around 1,200 kelvin—and appears to have clouds, reflecting its youth and ongoing contraction. A second directly imaged planet, PDS 70c, was identified later. Researchers have also studied possible circumplanetary material around the pair, but those disks are separate from the original achievement: directly imaging a confirmed planet in the act of formation.