Tasked to watch Earth, Japanese satellite makes big discovery on Venus

Assigned to monitor Earth, Japan’s Himawari-8 and -9 weather satellites have been effectively repurposed to detect variations in Venus’ cloud-top temperatures, uncovering hidden patterns in atmospheric waves.

Researchers, guided by the University of Tokyo, utilized data from 2015 to 2025 to assess brightness temperatures on both daily and yearly scales. This research emphasizes how meteorological satellites can enhance future planetary explorations and ground-based telescopes.

The Himawari-8 and -9 satellites, launched in 2014 and 2016, were initially created to observe Earth’s atmospheric events using their multispectral Advanced Himawari Imagers (AHIs). The research team compiled a data archive by retrieving all Venus images from the AHI datasets, uncovering 437 instances. Taking into account background noise and Venus’s perceived size in the images, they successfully monitored changes over time in cloud-top temperature during particular alignment phases of the satellite, Venus, and Earth.

After examining the data, the team validated differences in thermal tide amplitude and fluctuations in the amplitude of planetary waves over time. These results, despite being constrained by the AHI data’s resolution, indicated potential connections to changes in Venus’ atmospheric composition.

Observing the temperature changes in the cloud tops of Venus is essential for comprehending its atmospheric dynamics, encompassing thermal tides and large-scale planetary waves. Ground-based observations face restrictions because of Earth’s atmosphere and sunlight in the daytime.