For solar wind dials without any explanatory text, see this page. It also has a few dials that are not shown here. A web page with more explanatory text
is also available.
Current Space Weather Status
This "stoplight" shows the more severe of the following three gauges of space weather:
This index is based on the most recent USAF/NOAA estimated planetary
geomagnetic activity (KP) 1-hour index. Our index is determined as follows:
|Condition||Estimated (1-Hour) KP|
|Green||0 <= KP < 4|
|Yellow||4 <= KP < 7|
|Red||KP => 7|
This index is keyed to the estimated instantaneous asymptotic voltage across the polar cap, the
single most important measure of electrical power delivered to the atmosphere
from the solar wind. We now use data from the
ACE Real-Time Solar Wind
package since this spacecraft is tracked more often than WIND.
(The old estimate was based on observations from NASA's
An updated graph of
that estimate is still available.) The index is determined as follows:
|Condition||Polar Cap Potential (PCP) Range|
|Green||0 kV <= PCP < 100 kV|
|Yellow||100 kV <= PCP < 200 kV|
|Red||PCP >= 200 kV|
Note: Yellow-to-Green transitions will now occur at 90 kV, and Red-to-Yellow
transitions will occur at 190 kV. This should reduce condition changes
caused by small fluctuations near the thresholds.
This index is based on the forecasted geomagnetic event probabilities over
the next two days (section VI of the NOAA/SEC Forecast)
|Condition||Next Day Probabilites (P1)||Second Day Probabilities (P2)|
|Green||P1 <= 35%||P2 <= 35%|
|Yellow||35% < P1 <= 50%||P2 > 35%|
|Red||P1 > 50%||Not Applicable|
Latest Observations from the ACE spacecraft
Last Measurement (at Sun-Earth L1 Point): May 14, 2001 8:44 UT
Sun-Earth L1 Point is approximately 45 minutes upwind of the Earth.
Interplanetary Magnetic Field
You can now receive e-mail notification whenever the stoplight sets to red!
(Actually, you can be notified whenever any of these conditions change.) Just
send e-mail to
firstname.lastname@example.org with the following in the body of the message:
SUBSCRIBE SPACALRT first_name last_name
For "Joe User" to subscribe, this would be:
SUBSCRIBE SPACALRT Joe User
Stoplight state changes are now logged. There are three logs, one for each
condition index (KP,Solar Wind,and NOAA/SEC.) The earliest logged transition
occurred on January 23, 1999.
More about the solar wind's recent behavior can be found on my Current Solar Wind Conditions page.
Also, here's an index to Space Weather Resources.
Other items of interest include NOAA/SEC Current Conditions, my composite current Auroral Images page,
Windows on the Universe:
Space Weather, and Public Outreach Index,
Department of Space Physics and Astronomy, Rice University.
This page has been accessed times since March 22, 1996.
Please accept my apologies for the recent inavailability of this page. The
web server was taken down for an upgrade in late March 2000, and my account
was locked out in the process. It took until April 7, 2000 for me to regain
Andrew L. Urquhart
Department of Space Physics & Astronomy
Static information was last revised on 4/7/2000.