A team of Chinese scientists and their overseas counterparts have, for the first time, discovered evidence of a lunar tide-induced signal in the Earth's plasmasphere, the inner region of the magnetosphere below the Earth's crust, which is filled with cold plasma.

The study, jointly conducted by scientists from Shandong University, the Institute of Geology and Geophysics of the Chinese Academy of Sciences, and other institutes, was recently published in the journal Nature Physics.

According to scientists, effects caused by lunar tides were reported in the Earth's crust, oceans, neutral gas-dominated atmosphere and near-ground geomagnetic fields. However, whether a lunar tide effect existed in the plasma-dominated regions had not been explored.

Xiao Chao, the paper's co-first author, a researcher at Shandong University, says that they made the new findings by analyzing data from more than 10 satellites over the past four decades.

They found that the lunar tide-induced signal in the Earth's plasmasphere possesses distinct diurnal and monthly periodicities, which are different from the semi-diurnal and semimonthly variations dominant in the previously observed lunar tide effects in other regions.

The new findings expand our understanding of Earth-moon interactions in a direction that had not been previously considered, says Xiao.

They also provide important clues for future investigations in broader regions and two-body celestial systems, including other planetary systems in our solar system and beyond, the researcher adds.