NASA Data Enables New Discoveries About The Magnetosphere

One of the features of Earth that is critical to protecting life as we know it is the magnetosphere. The Earth's magnetosphere is a magnetic field that protects the planet from the constant bombardment of solar wind. Scientists believed waves traveling along the magnetosphere would ripple in the direction of the solar wind. However, a new study has shown some waves perform exactly the opposite of how they expected.

Magnetospheric waves transport energy, and by studying them, researchers can understand the complex way solar activity acts in the space around Earth. It's critically important to learn as much as possible about space weather because it can impact satellites in orbit around the planet and powerlines on the ground. Researcher Martin Archer, the lead author of the new study, says that understanding the boundaries of any system is a key problem.

Archer and the team focused on surface waves or waves that require a boundary to travel along. The boundary in this instance is the edge of the magnetosphere. Past research by Archer and colleagues determined that the magnetosphere's boundary vibrates like a drum. If a strong burst of solar wind hits the magnetosphere, it generates waves that move towards the Earth's magnetic poles before being reflected back.

The study considered waves that form across the entire surface of the magnetosphere, leveraging models created from observations by the NASA THEMIS mission. The team found that when a pulse of solar wind hits the magnetosphere, waves form that move back and forth between the magnetic poles of the Earth in the front of the magnetosphere, but some also form that travel against the solar wind.

At the front of the magnetosphere, the waves appear to stand still. Observations from the THEMIS satellites first hinted some waves could travel against the solar wind. Project researchers leveraged models to illustrate how energy from the solar wind coming from the sun and waves generated by the magnetosphere could cancel each other out. They liken that to walking up an escalator that is moving down, which would make you seem to stand still. Scientists believe that studying the waves around the Earth could help them understand similar boundaries around other planets.