EXPANDING SUNSPOT: In a span of only 24 hours, sunspot 826 has grown from a barely-visible speck into a Saturn-sized active region, and it is still growing. This large sunspot is crackling with low-level solar flares and may soon pose a threat for a major eruption. Readers who own a safely-filtered solar telescope will want to monitor this sunspot; it is changing by the hour. Or visit http://spaceweather.com to view up-to-date images and movies.