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> December 17, 1999:
Hour One: Earth Sciences Update
Take some sunspots, mix in a few volcanoes, a big chunk of ice, and the Earth's magnetic field, and you might get something similar to the meeting of the American Geophysical Union, which took place this week in San Francisco. On this hour of Science Friday, we'll be taking a look at a grab bag of science that was reported at the meeting.
About every eleven years, the sun's activity kicks into high gear, with more flares, sunspots, and other activity than normal. This peak in the sun's cycle is called the "solar maximum" - and sun-watchers around the world are gearing up for the coming maximum, expected to take place in the coming year. The solar max isn't of interest just for star-gazers, though. Flares and coronal mass ejections can affect life back on Earth by zapping power transmission grids, or blanking out radio signals. Astronauts need to be wary of flares lest they be scorched by the radiation. And many people have looked for links between solar cycles and cycles of natural phenomena on Earth. We'll find out what scientists are looking to learn from the peak in activity, and what's being done to protect Earth from fierce flares.
A coronal mass ejection (CME) can
send a wave of charged particles
out into space. (Yokkoh image)
| 
Sunspots look dark - but they're just
darker than the surrounding parts of
the sun. (NSO image) | 
What's a sunspot look like close
up? (Vacuum Tower Telescope,
NSO, and NOAO image) | 
Scientists use X-ray images
(soft x-rays seen here) to monitor
solar activity. (LASCO image) | 
This image (courtesy NASA's PIXIE imager)
shows x-ray emissions over the North Pole
on May 11, 1999. | One day in May there wasn't too much solar activity -- in fact, there was almost none. The solar wind, a stream of charged particles that flows out from the sun, cut off almost entirely. The density of the particles making up the "wind" decreased by almost 98%. The Earth's magnetosphere, the magnetic field that surrounds the planet, is normally buffeted and blown to one side by the solar wind. On this day, the magnetosphere was able to expand outward - almost becoming large enough to surround the moon.
The decrease in solar wind had strange effects back on Earth... including a most unusual auroral display near the North Pole. we'll find out what happened and why. | | And if you're wondering what effect solar eruptions might have on the Earth's climate, what about the effects of good old-fashioned volcanic eruptions? We'll talk with a scientist who says that all the gases and ash spewed out from volcanoes may not have the same effects everywhere on the globe. Mount Pinatubo, for example, may have warmed temperatures in some places -- though the global average temperature dropped, due to blocked sunlight. We'll find out more about the link between volcanoes and climate - and between climate and melting ice sheets - during this hour of Science Friday. | 
Mt. Pinatubo erupts, 1991. E.W.Wolfe, USGS Photo. |
Guests:
Alan Robock
Professor, Climatology
Rutgers University
New Brunswick, New Jersey
Victor Pizzo
Physicist, Space Environment Center
National Oceanic and Atmospheric Administration
Boulder, Colorado
Howard Singer
Chief, Research and Development Division
Space Environment Center
National Oceanic and Atmospheric Administration
Boulder, Colorado
Books/Articles Discussed:
Related Links:
Upcoming Solar Maximum
Space Environment Center
ACE Real Time Solar Wind
National Solar Observatory
Solar Data Analysis Center
SOHO: The Solar and Heliospheric Observatory
Solar Flare Theory
The Exploration of the Earth's Magnetosphere
What is the Magnetosphere?
Sacramento Peak: Sunspots and the Solar Cycle
Cascades Volcano Observatory HOME PAGE
U.S. Geological Survey, Volcano Hazards Program
Earthshots: Satellite Images of Environmental Change: Table of Contents
International Arctic Research Center
National Snow and Ice Data Center
- This segment produced by:
Karin Vergoth
Web producer:
Charles Bergquist
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