Featured Research

from universities, journals, and other organizations

Earth's Magnetic Field Expanded Immensely After "The Day The Solar Wind Ran Out Of Gas"

Date:
December 15, 1999
Source:
University Of Colorado At Boulder’s
Summary:
A rare space weather event May 11 marked by a sharp decrease in solar wind helped cause Earth's magnetosphere to balloon to more than 100 times its normal volume, reaching nearly to the moon in the process, according to a new study.

A rare space weather event May 11 marked by a sharp decrease in solar wind helped cause Earth's magnetosphere to balloon to more than 100 times its normal volume, reaching nearly to the moon in the process, according to a new study.

Daniel Baker, director of the University of Colorado at Boulder’s Laboratory for Atmospheric and Space Physics, said the density and speed of the particle-toting solar wind creates a dynamic pressure that confines Earth's magnetic field to form its magnetosphere. Under normal conditions, a cross-section of Earth’s magnetosphere resembles a halved apple, although a comet-like tail sweeps back from the side of the planet facing away from the sun.

But on May 11, the solar wind density – the number of energetic electrons and protons per cubic centimeter -- was only about 2 percent of normal, and the wind’s speed dropped by more than half. This caused the pressure on the magnetic field to plummet by more than 99 percent, said Baker, lead author on the study. The event was dubbed by some scientists as "The Day the Solar Wind Ran Out of Gas."

"This was a very rare occurrence that has been seen only a few times since satellites began taking solar wind measurements 35 years ago," he said. While the magnetosphere generally reaches out about 40,000 miles from Earth toward the sun, it stretched to nearly 235,000 miles on May 11, about the distance from the Earth to the moon.

A paper on the subject by Baker, CU graduate student Sean Yarborough and CU Research Associate Xinlin Li was presented at the fall meeting of the American Geophysical Union held Dec. 13 to Dec. 17 in San Francisco. Other co-authors included Niescja Turner and Shrikanth Kanekal of NASA's Goddard Space Flight Center, J.B. Blake of the Aerospace Corp. in Los Angeles and Howard Singer of NOAA’s Space Environment Center in Boulder.

NOAA is the National Oceanic and Atmospheric Administration.

Baker and his colleagues used data from the SAMPEX, POLAR, GOES, GPS and many other satellites to take data on Earth's Van Allen radiation belts, which are deeply embedded in the magnetosphere. The radiation belts became much more symmetric during the event, with the comet-like tail of radiation apparently disappearing in the process.

Although the density of energetic electrons in the solar wind returned to normal on May 12, as did the solar wind speed, the density of very high-energy electrons in the magnetosphere dropped mysteriously once again on May 13 and remained "severely depleted" for an extended period, said Baker.

"It appears this episode fundamentally changed the magnetosphere by causing the energetic electrons to all but disappear for about two months," said Baker. "Everything the solar wind was throwing at the magnetosphere should have re-started its engine after May 13, but for some reason it failed."

Although scientists once thought Earth’s radiation belts slowly waxed and waned and were not particularly dynamic, they recently have been shown to be powerful particle accelerators for the magnetosphere’s energetic electrons, he said.

The solar wind spins off the rotating sun much like a circular lawn sprinkler sprays water, accelerating up to nearly 1 million to 2 million miles per hour by the time it hits Earth's magnetosphere, said Baker.

"It’s possible that a large 'vacuum bubble’ formed on the edge of the sun and was blown toward Earth, causing the solar wind to slow and become less dense during the May 11 event," he said. "This illustrated the solar wind, like the radiation belts, are highly dynamic and variable."

Although the shape of the magnetosphere and the density of its charged particles returned to normal levels after about two months, the surprising 1999 phenomenon may prove significant to space-weather experts like Baker. "I think these rare, extreme events eventually will help us to understand how the magnetosphere's engine works under normal circumstances," he said.


Story Source:

The above story is based on materials provided by University Of Colorado At Boulder’s. Note: Materials may be edited for content and length.


Cite This Page:

University Of Colorado At Boulder’s. "Earth's Magnetic Field Expanded Immensely After "The Day The Solar Wind Ran Out Of Gas"." ScienceDaily. ScienceDaily, 15 December 1999. <www.sciencedaily.com/releases/1999/12/991215072215.htm>.
University Of Colorado At Boulder’s. (1999, December 15). Earth's Magnetic Field Expanded Immensely After "The Day The Solar Wind Ran Out Of Gas". ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/1999/12/991215072215.htm
University Of Colorado At Boulder’s. "Earth's Magnetic Field Expanded Immensely After "The Day The Solar Wind Ran Out Of Gas"." ScienceDaily. www.sciencedaily.com/releases/1999/12/991215072215.htm (accessed October 1, 2014).

Share This



More Earth & Climate News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Newsy (Sep. 30, 2014) A new study published by the World Wide Fund for Nature found that more than half of the world's wildlife population has declined since 1970. Video provided by Newsy
Powered by NewsLook.com
Seismic Activity Halts Recovery at Japan Volcano

Seismic Activity Halts Recovery at Japan Volcano

AP (Sep. 30, 2014) Rescuers were forced to suspend plans to recover at least two dozen bodies from near the summit of Mount Ontake in central Japan on Tuesday after increased seismic activity raised concern about the possibility of another eruption. (Sept. 30) Video provided by AP
Powered by NewsLook.com
Dolphins Might Use Earth's Magnetic Field As A GPS

Dolphins Might Use Earth's Magnetic Field As A GPS

Newsy (Sep. 30, 2014) A study released Monday suggests dolphins might be able to sense the Earth's magnetic field and possibly use it as a means of navigation. Video provided by Newsy
Powered by NewsLook.com
How To Battle Stink Bug Season

How To Battle Stink Bug Season

Newsy (Sep. 30, 2014) Homeowners in 33 states grapple with stink bugs moving indoors at this time of year. Here are a few tips to avoid stink bug infestations. 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