Above: This image, courtesy of Dr. Judith Lean at the US Naval Research Laboratory, shows three extreme ultraviolet (EUV) pictures of the Sun captured by the ESA/NASA Solar and Heliospheric Observatory at different times during the current solar cycle. In 1996, near solar minimum, the EUV Sun was nearly featureless. Now, near the peak of the cycle, the Sun is dotted by fiery regions of hot gas trapped in magnetic fields above sunspots and plages. These active regions produce copious numbers of EUV and X-ray photons that are absorbed in outer layers of our atmosphere before they reach Earth's surface. The red curve in the image is a computer model of the solar EUV flux at 304 Angstroms derived from ground-based Ca K images made at the Big Bear Solar Observatory.

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 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 vertical bars indicate the full range of daily sunspot numbers that were averaged to obtain monthly data points. Large excursions, like the one on April 2 when the daily Boulder sunspot number reached 301, are not uncommon.