January 20, 2000 -- What's 1.4 million kilometers across, covered with magnetic spots, and the hottest box office attraction in the Solar System? (Hint: It's bigger than Tom Hanks.)

With solar maximum just around the corner, the Sun is putting on a show that rivals the most sizzling Hollywood thrillers. Powerful solar flares and coronal mass ejections happen almost every day. You can't see them with the naked eye, but the European Space Agency and NASA have a front row seat, thanks to the Solar and Heliospheric Observatory (SOHO). SOHO monitors solar activity from a permanent vantage point 1.5 million kilometers ahead of the Earth in a around the L1 Lagrangian point. Unlike an Earthbound observer, it can see the Sun 24 hours a day.

Above: On January 18, 2000, the space-based Solar and Heliospheric Observatory Extreme Ultraviolet Imaging Telescope captured these images of a huge eruptive prominence escaping the Sun. Click on the animation for a close-up view of the figure "8" shaped eruption visible in the lower left corner of the animation.
 

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On January 18, 2000, SOHO spotted a spectacular prominence, pictured above in an animation spanning a 24 hour period. At maximum, the prominence was about 100 times wider than the Earth.

Prominences are loops of magnetic fields with hot gas trapped inside. Sometimes, as the fields become unstable, the they will erupt and rise off of the Sun in just a few minutes or hours. Beautiful prominences like these become more common as we approach solar maximum.
 

When will the solar maximum actually take place? Recent work by David Hathaway, a solar physicist at the Marshall Space Flight Center, and his collaborators indicate that the solar activity will peak around the middle of the year 2000.

 

"Our predictions have consistently targeted 2000 as the beginning of solar maximum," said Hathaway in a recent interview, "but the latest numbers suggest that the peak sunspot count in 2000 will be a bit lower than expected. The projected peak is comparable to, but lower than the peaks of the last two maxima (in 1989 and 1978). That would put all three of the recent sunspot maxima in the same class -- above average compared to all the sunspot cycles since the mid 1700's."

Above: By combining data about geomagnetic activity during the previous solar cycle with sunspot counts for the current cycle, David Hathaway and collaborators are able to predict when the next sunspot maximum will occur. [Click here for details]. According to their results, the sunspot number -- and other forms of solar activity -- will peak beginning in mid-2000. The dotted lines above and below the solid curve line indicate the prediction curve's range of error.

"The sunspot maximum is usually a broad peak. There is a two or three year period when activity is quite high. I expect solar activity to be highest in 2000 and 2001, and then in 2002 it may decline back to where we [were] in 1999."
 

Right: A January 10, 2000 SOHO EIT image showing an eruptive prominence on the Sun. .

During this period of heightened solar activity, the Sun puts on a nearly non-stop show. For instance, just one week ago SOHO captured another sequence of prominences. This time, the Extreme Ultraviolet Imaging telescope was observing in a mode with a higher-than-usual telemetry rate, due to the fact that the Large Angle Spectrometric Coronagraph (LASCO) instrument had its doors closed in anticipation of spacecraft maneuvers. The resulting movies (click on the image for a Quicktime animation) are awesome. If eruptions like these are directed toward the Earth they can cause a significant amount of aurora and other geomagnetic activity.

For more information about space weather see http://SpaceWeather.com. SOHO (the Solar and Heliospheric Observatory) is a mission of international cooperation between NASA and the European Space Agency. It is managed by the Goddard Space Flight Center for the NASA HQ office of Space Science.

Web Links

 

SpaceWeather.com -Science news and information about the Sun-Earth environment.

NOAA Space Environment Center -official site for space weather forecasts and information

Solar and Heliospheric Observatory -home page