From NASANews@luna.osf.hq.nasa.govWed Nov  8 13:14:11 1995
Date: Mon, 6 Nov 1995 16:19:25 -0500
From: NASA HQ Public Affairs Office <NASANews@luna.osf.hq.nasa.gov>
To: press-release-com@mercury.hq.nasa.gov
Subject: Space Disturbance Detected by NASA Satellite before
Reaching Earth

Don Savage
Headquarters, Washington, DC            November 6, 1995
(Phone:  202/358-1547)

Jim Sahli
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-0697)

RELEASE:  95-202

SPACE DISTURBANCE DETECTED BY NASA SATELLITE BEFORE REACHING EARTH

       A NASA spacecraft detected a huge interplanetary 
disturbance which struck the Earth's protective magnetic 
field on Oct. 18, producing a magnetic storm and auroral 
displays, or "Northern Lights" that persisted for two days. 

       The phenomenon was visible in the United States as 
far south as Denver, according to scientists at NASA's 
Goddard Space Flight Center, Greenbelt, MD, who reported 
critical satellite data to other government agencies and 
scientists around the world.

       The information was relayed electronically to the 
U.S. Air Force and to the National Oceanic and Atmospheric 
Administration's Space Environment Laboratory, in Boulder, 
CO, where evaluators issued an updated "space weather alert" 
to commercial satellite operators, electrical utilities and 
other organizations worldwide.

       "The rapid response to the Wind observations and the 
prompt issuance of the alert were made possible by advanced 
data systems, technology and networks," said Dr. Keith 
Ogilvie of Goddard, NASA's Project Scientist for Wind.  The 
central processing and distribution systems were developed 
and implemented by NASA and supported by the Wind science 
teams, NOAA, the Air Force, and international partners.

       The disturbance, called a "giant magnetic cloud," was 
65 million miles across and speeding toward the Earth at 
over 2.1 million miles per hour when it was detected at 3 
p.m. EST on Oct. 18 by NASA's Wind spacecraft.  Wind is an
unmanned spacecraft patrolling interplanetary space 662,000 
miles from Earth, pointed toward the Sun.  Invisible to 
normal telescopes and to the human eye, the cloud was 
composed of magnetic fields and electrified subatomic 
particles ejected from the outer atmosphere or corona of the Sun.

       About thirty minutes after the front edge of the 
giant cloud passed over the Wind probe, it swept over 
Japan's GEOTAIL satellite, which was located on the sunward 
side of the Earth in its 120,000 X 40,000 mile elliptical 
orbit.  GEOTAIL also gathered important scientific data.  
Minutes later, the disturbance struck the outer limits of 
the Earth's magnetic field, which acts as a protective 
buffer.  The impact compressed the magnetic field on the 
sunward side of the Earth and stretched it out away from the 
Sun on the night side, triggering the magnetic storm and aurora.

       "It was detected with instruments on Wind that sense 
the magnetic fields, particles and waves in interplanetary 
space," said Dr Ogilvie.  "This is a good example of what we 
had been expecting since Wind was launched Nov. 1, 1994.  
This wonderful observation is a great first birthday present 
from Wind."

       A complete analysis of the Oct.18 Wind data, and data 
from other spacecraft and instruments, may take months or 
years, but is expected to tell scientists much about how 
interplanetary disturbances propagate through space and 
affect the Earth's environment.  Future disturbances are 
anticipated as the 11-year sunspot cycle is expected to peak 
shortly after the year 2000, according to NASA scientists.

EDITOR'S NOTE:  A color drawing depicting the disturbance is 
available to news media representatives by calling the 
Headquarters Imaging Branch on 202/358-1900.  

Photo numbers are: 	Color:  95-HC-651  B&W:  95-H-664

       Users of the Internet World Wide Web can obtain 
background information on Wind, GEOTAIL and related space 
missions, and view scientific data on the Oct. 18 
disturbance at the following URL:

http://bolero.gsfc.nasa.gov/~solart/cloud/cloud.html 

                            -end-

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