Join NASA’s Langley Research Center and the National Alliance of Black School Educators for a series of free, interactive programs that allow you and your students to learn more about our home planet and the universe beyond through webcasts.
The Earth System
Feb. 26, 2010, 1 p.m. – 2:00 p.m. EDT
The components of the Earth system, the lithosphere (the solid planet), the hydrosphere (the water), the atmosphere (the air) and the biosphere (life), will be discussed. Learn about the various processes on the Earth system including the structure of the Earth’s interior and surface, the formation of impact craters, volcanism and volcanic craters, the circulation of the atmosphere and oceans, the water cycle (evaporation, condensation and precipitation), the formation of clouds, and meteorological phenomena. The interactions between the components of the Earth system will be also discussed.
Earth and Mars: A Tale of Two Planets
March 26, 2010, 1 p.m. – 2:00 p.m. EDT
Mars is a cold, dry, very inhospitable planet. Its thin atmosphere has a surface pressure of only about 6 millibars (the pressure of Earth’s atmosphere is about 1013 millibars). Scientists now think that early Mars was a very hospitable planet with abundant surface water in the form of lakes, rivers and even planetary-scale oceans. They believe it had an atmospheric pressure comparable to that of Earth. What caused the very divergent evolutionary paths of Earth and Mars? Scientists believe that some 500 million years after its formation about 4.6 billion years ago, Mars lost its planetary dipole magnetic field. The field had protected its atmosphere from the “sand-blasting” effects of the solar wind, the continuous stream of energetic protons, electrons and ions emitted by the sun into interplanetary space. Once Mars lost its planetary magnetic field, the direct interaction of the energetic solar wind particles with the atmosphere resulted in the planet’s losing more than 99 percent of its atmosphere. Once Mars lost the bulk of its atmosphere, surface liquid water was no longer stable and was either lost to space and/or migrated to the subsurface of Mars as frozen water.
Global Warming: Causes and Consequences
April 30, 2010, 1 p.m. – 2:00 p.m. EDT
The temperature of the surface of Earth and the other planets is controlled by incoming solar radiation and the outgoing thermal or infrared radiation generated at the surface by the absorption of the incoming solar radiation. As the surface-emitted thermal radiation travels upward through the atmosphere, certain atmospheric gases absorb and then re-emit the radiation. This process results in an additional warming of the surface. This additional warming is called the “greenhouse effect.” Gases that absorb and then re-emit thermal radiation are called “greenhouse gases.” Carbon dioxide, while only a very minor gas in the atmosphere, is an important greenhouse gas. Measurements indicate that atmospheric concentrations of carbon dioxide are increasing, most likely as a result of certain human activities, such as the combustion of fossil fuels for transportation and energy generation and the burning of vegetation for deforestation and other land-clearing activities. The causes and consequences of global warming will be discussed.
For more information about this series of webcast events, visit http://dln.nasa.gov/dln/