University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, November 23, 2009
Coffee, Tea & Snacks 4:15-4:30 PM

Phillip C. Chamberlin
NASA Goddard Space Flight Center
Connecting the Sun to the Earth Through Solar Irradiance

The solar photon output, which was once thought to be constant, varies over all time scales from seconds during solar flares to years due to the solar cycle, and even longer-term variations throughout the life of the Sun. These solar variations cause significant deviations in the Earth and space environments on similar time scales, such as affecting the atmospheric densities and composition of particular atoms, molecules, and ions in the atmospheres of the Earth and other planets. These changes then affect many things including satellite drag, radio communications, and the accuracy of the Global Positioning System (GPS). Presented and discussed will be examples of the accurate, space-based measurements of the integrated photon output of the Sun, referred to as the solar irradiance, with the main focus on the X-ray and ultraviolet wavelength regions of the spectrum as well as the total solar irradiance (TSI). Connections will then be made to show how changes in the solar ultraviolet irradiance on the minutes to years time scales drive changes in the Earth, Moon, and Mars and lead to challenges in a society that is becoming more and more dependent on technologically.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Catha Stewart at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.