NASA researchers study how the solar system’s galactic journey affects Earth’s climate

Researchers at NASA’s SHIELD center are investigating how the movement of the heliosphere through the Milky Way has influenced Earth’s climate over millions of years. By using computer modeling, the team traced the solar system’s six-billion-year journey to understand how different galactic environments may have affected atmospheric conditions.

A study published in the Annual Review of Astronomy and Astrophysics, led by principal investigator Merav Opher of Boston University, indicates that the Sun has encountered cold gas and dust clouds at least three times in recent millions of years. These encounters occurred approximately two to three million, six to seven million, and thirteen to fourteen million years ago.

Simulations suggest that when Earth’s atmosphere interacted with these cold, dense hydrogen clouds, it triggered changes in water vapor and upper-atmospheric behavior. These shifts likely altered surface conditions and may have contributed to significant climatic changes, such as historical ice ages.