# Exoplanet and protoplanet discoveries

> Live situation record from CLSTR: https://clstr.news/situations/exoplanet-and-protoplanet-discoveries
> Updated: 2026-09-12T13:55:34.000Z. Sources: 7. Developments: 2.

Astronomers have reported two significant findings regarding planetary bodies outside our solar system.

Researchers identified GJ 523b, a “mega-Earth” with a mass approximately 23.5 times that of Earth. Despite its size, the planet appears to be primarily rocky rather than a gas giant, a characteristic that challenges current models of planetary formation. Scientists suggest the planet may have lost its original thick atmosphere through stellar radiation or planetary collisions.

In a separate discovery, evidence of a massive protoplanet was detected 430 light-years away. Using the ALMA radio telescope, astronomers observed gas and dust disturbances indicating a forming gas giant with a mass estimated between four and five times that of Jupiter. 

Recent details confirm the object is located around the star J16120, situated roughly 32 astronomical units from its host star. While the protoplanet has not been photographed directly, its presence is inferred from structural alterations in the surrounding material. An international team of researchers intends to conduct further observations using the Very Large Telescope to better understand the object’s temperature and mass.

## Claims

- Astronomers have detected evidence of a massive planet in the process of formation. (corroborated by 4 sources)
- The object's mass is estimated to be between four and five times that of Jupiter. (corroborated by 4 sources)
- The ALMA radio telescope was used to detect unusual gas movements indicating the presence of the protoplanet. (corroborated by 4 sources)
- The protoplanet is located approximately 32 astronomical units from its host star. (corroborated by 4 sources)
- The planet has not been directly photographed; its existence is inferred from gas movement patterns. (corroborated by 4 sources)
- The discovery may provide insights into the formation of gas giants like Jupiter and Saturn in our own Solar System. (corroborated by 4 sources)

## Timeline

### 2026-09-12: Astronomers discover giant protoplanet 430 light-years from Earth

Astronomers have discovered a giant protoplanet forming 430 light-years away. The object, 4-5 times the mass of Jupiter, was detected via gas movements around the star J16120 using the ALMA radiotelescope.

5 sources. https://clstr.news/cluster/protoplanet-discovery-massive-gas-giant-forming-430-light-years-away

### 2026-09-12: Exoplanet GJ 523b discovered with 23 times Earth's mass

Astronomers discovered GJ 523b, a massive exoplanet 23.5 times the mass of Earth that remains rocky instead of becoming a gas giant, challenging current planetary formation theories.

2 sources. https://clstr.news/cluster/exoplanet-gj-523b-discovered-with-23-times-earths-mass

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Cite as: Exoplanet and protoplanet discoveries. CLSTR, https://clstr.news/situations/exoplanet-and-protoplanet-discoveries