The Solar and Heliospheric Observatory (SOHO) turns 25 this week. Originally designed to operate for only two years, SOHO has lived through two complete solar cycles (1995 - now). During those long years, SOHO discovered more than 4000 comets, alerted Earth to 30,000 CMEs , found the first 'solar tsunamis,' and endeared itself as the #1 favorite spacecraft of Spaceweather.com.