Earth may have lost the Sun’s protective shield millions of years ago

NASA-funded studies suggest Earth’s climate has been influenced by both the Sun’s travels through dense regions of the Milky Way and the violent superflares of its youth. Those events may help explain ancient ice ages as well as how early Earth stayed warm enough for liquid water when the Sun was much dimmer. Earth may have lost the Sun’s protective shield millions of years ago.

(Conceptual illustration showing the heliosphere.). Two recent NASA-funded studies suggest that events from the Sun’s distant past may have influenced Earth’s climate in unexpected ways, from helping drive ancient temperature shifts to keeping the young planet warm enough for liquid water and possibly life. One study from NASA’s SHIELD (Solar Wind with Hydrogen Ion charge Exchange and Large-Scale Dynamics) center, one of NASA’s DRIVE (Diversify, Realize, Integrate, Venture, Educate) Science Centers, examines how the heliosphere moved through the Milky Way over time.

The heliosphere is the vast protective bubble produced by the Sun that surrounds the solar system. Researchers found that changes in the galactic environment around this bubble may have affected conditions on Earth. A separate study led by a NASA scientist explores another ancient puzzle: how a much dimmer young Sun could have kept Earth warm.