Solar Wind Pressure Lowest in 50 Years

“The entire sun is blowing solar wind significantly less harder, about 20% to 25% less harder and 13% lower temperature, than it was during the previous solar minimum a decade ago. ...Over the entire record of solar wind observations (about 50 years), this is the lowest prolonged pressure that we’ve ever observed.”

– Dave McComas, Ph.D., Solar Wind Principal Investigator, Ulysses

Sun depicted as bright white-yellow object on left blowing off electrons, protons and some heavy ions at nearly 1 million mph (400 kilometers/second) past the earth and out through the solar system. NASA's and ESA's Ulysses spacecraft has measured the pressure of the solar wind decreasing 20% to 25% since 1990. Implications for Earth and solar system are unclear. Graphic illustration by NASA Goddard Space Flight Center.

September 23, 2008 Pasadena, California - NASA produced a media teleconference today with Ulysses spacecraft scientists to announce, “The entire sun is blowing significantly less hard, about 20% to 25% less hard, than it was during the previous solar minimum a decade ago and its solar wind temperature has lowered 13%.” Ulysses is the first spacecraft from Earth to orbit around the poles of the sun. Since its launch on October 6, 1990, from the Space Shuttle Discovery (mission STS-41) as a joint venture of NASA and the European Space Agency, Ulysses has completed almost three orbits around the sun's poles that began with the 1990 solar minimum, included the 2000 solar maximum and is running out of heat and power as it nearly completes a third orbit during this 2008 solar minimum that has had a prolonged period without sunspots.

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