When the Photo voltaic Wind Slams Into Earth’s Magnetosphere, a Shocking Stillness Ensues

An animated illustration of magnetospheric waves, in gentle blue. On the entrance of the magnetosphere, these waves look like nonetheless. Credit score: Martin Archer/Emmanuel Masongsong/NASA

Power from the photo voltaic wind interacting with the magnetospheric ‘bubble’ round Earth creates waves of vitality that seem to face nonetheless.

This new discovering, from analysis led by Imperial scientists, improves our understanding of the circumstances round Earth that contribute to ‘area climate,’ which may affect our expertise from communications satellites in orbit to energy traces on the bottom.

The Solar releases a stream of charged particles known as the photo voltaic wind. On the Earth’s floor, we’re shielded from this barrage by the magnetosphere – a bubble created by the Earth’s magnetic subject.

When the photo voltaic wind hits the magnetosphere, waves of vitality are transferred alongside the boundary between the 2. Scientists thought the waves ought to ripple within the route of the photo voltaic wind, however the brand new research, printed lately in Nature Communications, reveals some waves just do the other.

Standing waves

Beforehand, lead researcher Dr. Martin Archer, from the Division of Physics at Imperial, and his colleagues established the magnetosphere’s boundary vibrates like a drum. When a drumstick-like pulse from the photo voltaic wind strikes the very entrance of our magnetospheric bubble, waves race towards Earth’s magnetic poles and get mirrored again.

The newest work considers the waves that kind throughout the whole floor of the magnetosphere, utilizing a mixture of fashions and observations from
Film of the simulation outcomes on the equator (left) and midday meridian (proper). The boundary of the magnetosphere (black) strikes as a consequence of floor waves, which compresses (pink) or rarefies (blue) the magnetosphere. The oscillations have additionally been transformed into accompanying audio.

The group used fashions as an example how the vitality of the wind coming from the Solar and that of the waves going in opposition to it may cancel one another out, creating ‘standing waves’ that contain loads of vitality however seem to go nowhere.

Dr. Archer mentioned: “It’s much like what occurs should you attempt strolling up a downwards escalator. It’s going to seem like you’re not transferring in any respect, although you’re placing in a great deal of effort.”

These standing waves can persist longer than people who journey with the photo voltaic wind. Which means they’re round longer to speed up particles in near-Earth area, resulting in potential impacts in areas like Earth’s radiation belts, aurora, or ionosphere.

The researchers additionally say that standing waves could happen elsewhere within the universe, from the magnetospheres of different planets to the peripheries of black holes.

Waves of sound

The researchers additionally translated the electromagnetic alerts from the THEMIS satellites into audio, permitting us to hearken to the sounds of the waves touring throughout the magnetospheric boundary.

Compressions and rarefactions of the magnetosphere as measured by the THEMIS satellites transformed into audible sound.

Dr. Archer added: “Whereas in a simulation we will see what’s occurring in all places, satellites can solely measure these waves the place they’re giving us solely time-series, wiggly traces. This form of knowledge is definitely finest suited to our sense of listening to than sight, so listening to the information can usually give us a extra intuitive concept of what’s occurring.

“You’ll be able to hear the deep respiratory sound of the standing floor waves persist all through, rising in quantity as every pulse hits. Increased pitched sounds, related to different kinds of waves, don’t final practically as lengthy.”

For extra on this analysis, see Shocking Standing Waves at Fringe of Earth’s Magnetic Bubble Present in NASA Information.

Reference: “Magnetopause ripples going in opposition to the move kind azimuthally stationary floor waves” by M. O. Archer, M. D. Hartinger, F. Plaschke, D. J. Southwood and L. Rastaetter, 6 October 2021, Nature Communications.
DOI: 10.1038/s41467-021-25923-7