APL Colloquium

November 19, 1999

Colloquium Topic: Space Weather

The Sun provides many inputs to the terrestrial environment. Space weather refers to the conditions in space that affect us on Earth. The impact of this variability onto our increasing technological society needs to be better understood. The Earth is continually being bathed by the solar wind, a continuous flow of ionized particles and magnetic field from the Sun. This highly variable wind provides a highly variable input into the Earth's magnetosphere. One of the consequences of this variability are the aurora borealis, which are generally seen at northern latitudes, but sometimes are seen to very low latitudes. Also, electric power grids experience induced currents resulting in transformer failures and blackouts for example. In recent years, a shift has occurred in our understanding of the cause of these effects. The solar flare has been replaced by the coronal mass ejection as being the cause of geoma genetic disturbances. These events are shown very beautifully in the SOHO data. What do we know about such events and what will new missions such as Solar Terrestrial Relations Observatory (STEREO) provide?

Colloquium Speaker: Russell Howard

Dr. Russell A. Howard received a B.S. degree from the University of Maryland in Mathematics in 1964 and a Ph.D. in Chemical Physics in 1969. He was a National Research Council Postdoctoral Research Associate at the Naval Research Laboratory from 1969-1971 in ultraviolet spectroscopy and joined the staff of NRL in 1971. In 1998 he was appointed the head of the Solar Physics Branch of NRL. Dr. Howard has been active in developing experimental and analytical techniques to understand the physics of the coronal mass ejection phenomenon - its initiation, propagation, and eventual interplanetary effects. As an experimental physicist he developed the Change Coupled Devices (CCD) and CCD cameras for Large Angle Spectrometric COronograph (LASCO) and Extreme ultra-violet Imaging Telescope (EIT) for which he received the NRL Royalty Award. He was the Project Scientist and is now the Principal Investigator of the LASCO experiment on the SOlar and Heliospheric Observatory (SOHO) satellite, as well as a co-investigator of the EIT experiment on SOHO.