# JWST reveals dawn-dusk atmosphere split on ultra-hot exoplanet WASP-121 b

> **Open Intelligence Dossier** · First detected: 2026-06-11 17:26 UTC · Category: Science

## Executive Summary
New James Webb Space Telescope observations reveal distinct atmospheric conditions between dawn and dusk on the ultra-hot exoplanet WASP-121 b.

## Intelligence Brief
Data captured by the James Webb Space Telescope shows that the atmosphere of WASP-121 b varies significantly between its morning and evening sides. The planet experiences extreme heat, which results in the breakdown of water molecules. ScienceBlog.com, ScienceDaily, and Phys.org report that these differences create distinct weather patterns at dawn and dusk.


Related coverage from IFLScience discusses atmospheric phenomena on WASP-94A b, where rock clouds appear to form and vanish on a diurnal cycle. Universe Today highlights that these findings are supported by a new method for detecting clouds on exoplanets. Future updates will likely depend on continued analysis of JWST imaging and the application of new cloud-detection methodologies.


Coverage does not yet specify the full chemical composition of these dawn-dusk atmospheric divides.

## Multi-Source Evidence Table
| Source Outlet | Headline | Verification URL |
|---|---|---|
| ScienceBlog.com | A Planet So Hot Its Water Falls Apart Has Different Weather at Dawn and Dusk | [Source Link](https://news.google.com/rss/articles/CBMitwFBVV95cUxQUDZHUkdwdVRxd1JFRG5fUmpXWkpMUS0zRXByMUdFbXlKRzFvSlA5NEhZWXpXdkdlNHMxYmFIY2xxeC1ScXNmeGppVXNYeGIwWDl0cG51WGg0TlNTZmJjMTNOZ0wtT0J3ZFY1SUFhRU9IRVpKMUdrTGVYOVZIZGZIakhOai1ZbjZDcDJTNEc1UlZuWUoxcXJIc3BwWi1JdHBaTm02V01QSzcyYjRwM01maWpsdkpfWk0?oc=5) |
| Universe Today | New Cloud-Detecting Method Will Help Astronomers Characterize Exoplanets | [Source Link](https://news.google.com/rss/articles/CBMisAFBVV95cUxNc3Z2eUtIVWdCbk1kVTl3ZUlhVmNpSzRRZ3JPcjBIaUdENUZUWnRFMGhnWW9DZ3dyV01sTHBBRFE1ek55dnlaaWlzVWk2QTFNTHFpUU1EVzgtSTJUUDc4S3hmVlhYck5OZlYtNFkzUHY1Vm92bndTSW5HbVN1Q2RQMlFxWF9KQXU4UmNBekJhWnYydy02Mmc2N0dsbmRDUWx1ZFRCdFZkOTU5VGpXOTQ3bg?oc=5) |
| ScienceDaily | James Webb reveals two completely different twilights on an alien world | [Source Link](https://news.google.com/rss/articles/CBMib0FVX3lxTE83amQ2UHFLUU1aX2xVb2V5SkxBNG5aNGlNZ2ZtdFdaamhkT2Z5Rk5DSUdsaU9vWEFyRGpHS0daNmZVMS1IX2VsenFlWHM2eEEtckF1TkhHc3pCNW1qNWwwdzMyX1hlVXJPb2tRRE1mdw?oc=5) |
| IFLScience | WASP-94A b: The Exoplanet Where Clouds Of Rock Form In The Morning And Vanish Every Night | [Source Link](https://news.google.com/rss/articles/CBMivgFBVV95cUxOT29RR1ZpLXZ0akJTLXh4T1VRNFFBTGNMQjJ0dGZBZm42Qlh1SmVPeTlXX0k0Y3FhdGlqNi1iXzlrRU56YTBOOENGajRQdHZDcFpPd29KWmMxLVNLSWVNbmhnS3NnWGs0R0tKMkcxdzdzaW1keTg1MFdPTk9aT09VRWxSYXdZYmFxMUprcUFjdWNhUFVUUWpBeUJCcFVRSDNwbC1SZkNhYWpjV0xjR3hPbWtiRXhhRUlGUUxMVmNB?oc=5) |
| Phys.org | JWST reveals dawn-dusk atmosphere split on ultra-hot exoplanet WASP-121 b | [Source Link](https://news.google.com/rss/articles/CBMid0FVX3lxTE1wSXhyZGJnSmZOcVRCNG1yREdWeEVGY2hCTXdlMXZ4ZjJLQ19WMlJoUDFwWlhNcW5oUDFIcWpkMWhzelFDTFRlNjVnN0o5MTZ0eE5oUlMyQnBiN2F3S0ZRZ3NIVTFZZnc2a1A5WmtJcDZveUFoMS1n?oc=5) |

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*Canonical Source: https://pulse.byoviral.com/trend/2026-06-11/jwst-reveals-dawn-dusk-atmosphere-split-on-ultra-hot-exoplanet-wasp-121-b*