Moon offers unique view of Earth's radiation signature: study

BEIJING -- A new study has revealed that observing Earth from the moon serves as a powerful way of seeing the planet's true, global radiation signature, cutting through the "noise" of local weather to capture its core climate patterns.

Earth's radiation budget, the balance between the energy it receives from the sun and the energy it radiates back into space, is fundamental to the climate. While satellites have been crucial in conducting such studies, they do face limitations. Low-Earth orbit satellites see different parts of the planet at different times, while geostationary satellites only watch a fixed hemisphere. This makes it hard to get a complete, consistent and continuous picture of Earth's entire energy output.

Published in the Journal of Geophysical Research: Atmospheres, this new research endeavor confirms that a moon-based platform effectively overcomes these limitations by providing a permanent, full-disk view of the planet.

"From the moon, Earth appears as a single, complete disk," explained Ye Hanlin, a researcher from the Institute of Atmospheric Physics at the Chinese Academy of Sciences (CAS), and the study's first author. "This allows us to extract the planet's dominant radiation signals while suppressing the interference from small-scale, local weather events."

The research team found that about 90 percent of the changes in Earth's emitted radiation, as seen from the moon, can be described via simple, planet-wide mathematical patterns called spherical harmonics.

These patterns act like Earth's unique global "radiation fingerprint." This process effectively performs "noise reduction" on the planet's energy signal, clearly revealing the large-scale features that matter most for climate studies, Ye said.

The study also decoded rhythmic cycles in this radiation data. Variations linked to lunar phases, the moon's orbital motion and Earth's daily rotation all leave distinct signatures in observed radiation patterns.

"A moon-based platform provides a new, long-lasting and holistic view of Earth, which is highly unique," said Guo Huadong, an academician of the CAS, and the study's corresponding author.

The findings confirm that this "big picture" perspective from the moon can provide critical support for accurately measuring Earth's outgoing radiation, ultimately advancing the understanding and monitoring of global climate change, he added.