Observations of CMEs from SOHO/LASCO

The LASCO experiment on board the SOHO satellite has been making observations of the solar corona out to 30 Ro since first light on 29 December 1995, and routinely since 15 May 1996. Over 120 coronal mass ejections have been observed to date. LASCO represents a significant advance over previous coronagraphs in many ways, but principally in an expanded field of view, increased sensitivity and increased dynamic range. The satellite, orbiting about the Lagrangian point, L1, is in continual sunlight, providing the opportunity to view the corona continuously, uninterrupted by orbit night as is common with near-Earth orbits. While the CMEs observed by LASCO are similar to those observed with previous coronagraphs, there are several new aspects: (1) Many are accompanied by a global response of the solar corona, (2) Many show acceleration to the edge of the field, (3) Disconnection is a frequent occurrence, (4) CMEs are occurring more frequently than had been expected at this minimum phase of the solar activity cycle, and (5) CMEs undergo extensive internal evolution as they move outward.