In a groundbreaking discovery, scientists have confirmed the existence of a long-theorized electric field around Earth, known as the “ambipolar electric field,” which plays a critical role in shaping our planet’s atmosphere. First hypothesized over 60 years ago, this weak but significant phenomenon has been observed for the first time, thanks to recent measurements from NASA’s Endurance rocket mission. The findings, published in Nature, reveal that this electric field drives a “polar wind” that propels charged particles from Earth’s upper atmosphere into space at supersonic speeds.
According to NASA, the ambipolar electric field is a key factor in the continuous outflow of particles above Earth’s poles, lifting them to altitudes higher than they would otherwise reach. This process, in turn, has had a profound impact on the evolution of our planet’s atmosphere, particularly in the ionosphere, a crucial layer of Earth’s upper atmosphere.
“Something had to be drawing these particles out of the atmosphere,” explained Glyn Collinson, principal investigator of the Endurance mission at NASA’s Goddard Space Flight Center and lead author of the study. The ambipolar electric field, now confirmed, acts like a conveyor belt, steadily lifting the atmosphere into space and driving atmospheric escape.
The discovery opens new avenues for understanding not only Earth’s atmospheric dynamics but also those of other planets. Since the ambipolar field is created by the internal dynamics of an atmosphere, similar fields are expected to exist on planets like Venus and Mars. This could provide crucial insights into the atmospheric evolution of these planets and help determine their potential habitability.
“Any planet with an atmosphere should have an ambipolar field,” Collinson said. “Now that we’ve finally measured it, we can begin learning how it’s shaped our planet as well as others over time.”
This breakthrough offers a new perspective on the complex movements and evolution of planetary atmospheres, providing important clues to the history of Earth and beyond.