A Cloudy Day in Space

On October 18, 1995, the NASA WIND spacecraft detected a huge magnetic cloud traveling toward the earth at 2.1 million miles per hour.

Such interplanetary clouds cause magnetic storms on earth, and often affect power grids and communications systems. NASA alerted the U.S. Air Force and the government's Space Environment Center (SEC) in Boulder, Colorado, of the detection of the cloud. SEC sent a "space weather alert" to commercial communications satellite operators, electric utilities, and other organizations around the world to warn them of the cloud's approach.

The cloud ejected from the sun was 65 million miles across. The drawing shows the cloud enveloping the earth's magnetic field. The cloud compressed the earth's magnetic field on the sun side and stretched it out on the night side. This caused a large magnetic storm and a display of northern lights, or aurora borealis, that was seen as far south as Denver, Colorado. North American auroras are normally seen only in Canada and Alaska, and occasionally in the northern United States.

The WIND spacecraft is part of the International Solar-Terrestrial Physics (ISTP) Program.

More Cool Stuff

To learn more about magnetic storms, northern lights and the earth's space environment, check out these resources.

The Exploration of the Earth's Magnetosphere:

http://lepmp.gsfc.nasa.gov/Education/Intro.html

The Space Environment Center's Primer on the Space Environment:

http://www.sel.noaa.gov/primer/primer.html

Michigan Technical University Aurora homepage:

http://www.geo.mtu.edu/weather/aurora/

The University of Alaska forecast of auroral activity:

http://www.pfrr.alaska.edu/~pfrr/AURORA/INDEX.HTM

The aim of ISTP is to better understand the earth's space environment and how the sun affects it. To learn more about ISTP, WIND, and the other partners in the program, check out these resources.

The International Solar Terrestrial Physics Program:

http://nssdc.gsfc.nasa.gov/space/istp/istp.html

The WIND Mission:

http://nssdc.gsfc.nasa.gov/space/istp/wind.html

The NASA Space Physics Program:

http://umbra.nascom.nasa.gov/spd/spd.html

The images and background information were provided courtesy of Mr. James Sahli of the NASA Goddard News.

Check out other observations in the Observation of the Week Archive.