Featured Research

from universities, journals, and other organizations

Earth's magnetosphere behaves like a sieve

Date:
October 24, 2012
Source:
European Space Agency (ESA)
Summary:
Our protective magnetic bubble lets the solar wind in under a wider range of conditions than previously believed. Earth’s magnetic field is our planet’s first line of defense against the bombardment of the solar wind. This stream of plasma is launched by the Sun and travels across the Solar System, carrying its own magnetic field with it. Depending on how the solar wind’s interplanetary magnetic field – IMF – is aligned with Earth’s magnetic field, different phenomena can arise in Earth’s immediate environment.

Solar wind entry at low latitudes.
Credit: AOES Medialab

ESA's quartet of satellites studying Earth's magnetosphere, Cluster, has discovered that our protective magnetic bubble lets the solar wind in under a wider range of conditions than previously believed.

Related Articles


Earth's magnetic field is our planet's first line of defence against the bombardment of the solar wind. This stream of plasma is launched by the Sun and travels across the Solar System, carrying its own magnetic field with it.

Depending on how the solar wind's interplanetary magnetic field -- IMF -- is aligned with Earth's magnetic field, different phenomena can arise in Earth's immediate environment.

One well-known process is magnetic reconnection, where magnetic field lines pointing in opposite directions spontaneously break and reconnect with other nearby field lines. This redirects their plasma load into the magnetosphere, opening the door to the solar wind and allowing it to reach Earth.

Under certain circumstances this can drive 'space weather', generating spectacular aurorae, interrupting GPS signals and affecting terrestrial power systems.

In 2006, Cluster made the surprising discovery that huge, 40 000 km swirls of plasma along the boundary of the magnetosphere -- the magnetopause -- could allow the solar wind to enter, even when Earth's magnetic field and the IMF are aligned.

These swirls were found at low, equatorial latitudes, where the magnetic fields were most closely aligned.

These giant vortices are driven by a process known as the Kelvin-Helmholtz (KH) effect, which can occur anywhere in nature when two adjacent flows slip past each other at different speeds.

Examples include waves whipped up by wind sliding across the surface of the ocean, or in atmospheric clouds.

Analysis of Cluster data has now found that KH waves can also occur at a wider range of magnetopause locations and when the IMF is arranged in a number of other configurations, providing a mechanism for the continuous transport of the solar wind into Earth's magnetosphere.

"We found that when the interplanetary magnetic field is westward or eastward, magnetopause boundary layers at higher latitude become most subject to KH instabilities, regions quite distant from previous observations of these waves," says Kyoung-Joo Hwang of NASA's Goddard Space Flight Center and lead author of the paper published in the Journal of Geophysical Research.

"In fact, it's very hard to imagine a situation where solar wind plasma could not leak into the magnetosphere, since it is not a perfect magnetic bubble."

The findings confirm theoretical predictions and are reproduced by simulations presented by the authors of the new study.

"The solar wind can enter the magnetosphere at different locations and under different magnetic field conditions that we hadn't known about before," says co-author Melvyn Goldstein, also from Goddard Space Flight Center.

"That suggests there is a 'sieve-like' property of the magnetopause in allowing the solar wind to continuously flow into the magnetosphere."

The KH effect is also seen in the magnetospheres of Mercury and Saturn, and the new results suggest that it may provide a possible continuous entry mechanism of solar wind into those planetary magnetospheres, too.

"Cluster's observations of these boundary waves have provided a great advance on our understanding of solar wind -- magnetosphere interactions, which are at the heart of space weather research," says Matt Taylor, ESA's Cluster project scientist.

"In this case, the relatively small separation of the four Cluster satellites as they passed through the high-latitude dayside magnetopause provided a microscopic look at the processes ripping open the magnetopause and allowing particles from the Sun direct entry into the atmosphere."


Story Source:

The above story is based on materials provided by European Space Agency (ESA). Note: Materials may be edited for content and length.


Journal Reference:

  1. K.-J. Hwang, M. L. Goldstein, M. M. Kuznetsova, Y. Wang, A. F. Viñas, D. G. Sibeck. The first in situ observation of Kelvin-Helmholtz waves at high-latitude magnetopause during strongly dawnward interplanetary magnetic field conditions. Journal of Geophysical Research, 2012; 117 (A8) DOI: 10.1029/2011JA017256

Cite This Page:

European Space Agency (ESA). "Earth's magnetosphere behaves like a sieve." ScienceDaily. ScienceDaily, 24 October 2012. <www.sciencedaily.com/releases/2012/10/121024101654.htm>.
European Space Agency (ESA). (2012, October 24). Earth's magnetosphere behaves like a sieve. ScienceDaily. Retrieved October 26, 2014 from www.sciencedaily.com/releases/2012/10/121024101654.htm
European Space Agency (ESA). "Earth's magnetosphere behaves like a sieve." ScienceDaily. www.sciencedaily.com/releases/2012/10/121024101654.htm (accessed October 26, 2014).

Share This



More Earth & Climate News

Sunday, October 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Gets Climate Deal, UK PM Gets Knock

EU Gets Climate Deal, UK PM Gets Knock

Reuters - Business Video Online (Oct. 24, 2014) — EU leaders achieve a show of unity by striking a compromise deal on carbon emissions. But David Cameron's bid to push back EU budget contributions gets a slap in the face as the European Commission demands an extra 2bn euros. David Pollard reports. Video provided by Reuters
Powered by NewsLook.com
Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) — Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) — A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Fast-Moving Lava Headed For Town On Hawaii's Big Island

Fast-Moving Lava Headed For Town On Hawaii's Big Island

Newsy (Oct. 24, 2014) — Lava from the Kilauea volcano on Hawaii's Big Island has accelerated as it travels toward a town called Pahoa. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins