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May 24, 2006

For Immediate Release


Media Contacts

Kristi Marren (The Johns Hopkins University Applied Physics Laboratory)
Phone: 240-228-6268

Nancy Neal Jones (NASA Goddard Space Flight Center)
Phone: (301) 286-0039
Nancy.G.Neal@nasa.gov


Two APL-Built Instruments Observe Recent Total Solar Eclipse

APL scientists have produced this image of the TIMED spacecraft's observations of the March 29, 2006, total solar eclipse. The data was acquired by TIMED's Global Ultraviolet Imager (GUVI) instrument as the eclipse progresses.

The first of the two orbit swaths (the one furthest to right in the image) shown in the image does not occur in the region of the eclipse. The position of the center of the moon's shadow, or umbra, is shown as it moves from Brazil across Africa.

In the second swath (the one furthest to the left of the image), GUVI images the region of the moon's shadow on Earth. During that time the TIMED spacecraft flies past the shadow region and sees the dramatic decrease in the temperature and brightness of the upper atmosphere where the moon's shadow falls. This is indicated by the dashed line in the second swath where GUVI looked toward the east to see the affected region.

Credit: Johns Hopkins APL


APL scientists have produced this video clip of the TIMED spacecraft's observations of the March 29, 2006, total solar eclipse. The data was acquired by TIMED's Global Ultraviolet Imager (GUVI) instrument as the eclipse progresses.

The first orbit swath shown in the clip does not occur in the region of the eclipse. The position of the center of the moon's shadow, or umbra, is shown as it moves from Brazil across Africa.

In the second and third swaths, GUVI images the region of the moon's shadow on Earth. During that time the TIMED spacecraft flies past the shadow region and sees the dramatic decrease in the temperature and brightness of the upper atmosphere where the moon's shadow falls. This is indicated by the dashed line in the second swath where GUVI looked toward the east to see the affected region.

In the third swath GUVI again sees the eclipse region, but is now looking back towards the west. Once again the dashed line indicates where the solar eclipse has led to a cooling of the atmosphere. The last swath shows the atmosphere where the eclipse track has already passed and recovered. Each of the swaths is separated by about 100 minutes — the time it takes TIMED to orbit the Earth.

Credit: Johns Hopkins APL

Space scientists from The Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md., got a first-hand look at what happens to Earth's atmosphere when the sun was abruptly "turned off" during the March 29, 2006, total solar eclipse.

APL scientists are now modeling unique observations of the eclipse captured by two APL-built instruments and the only two active space-based ionospheric-thermospheric imagers currently in operation: the Global Ultraviolet Imager (GUVI) aboard NASA's TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) spacecraft, built and operated by APL; and the Special Sensor Ultraviolet Imager (SSUSI) aboard an Air Force Defense Meteorological Satellites Program (DMSP) spacecraft.

"The TIMED and DMSP spacecraft were in just the right spot at the right time to image the upper atmosphere as the sun was eclipsed," says Larry Paxton, project scientist for the GUVI and SSUSI instruments. "These instruments provided the first and only look at the altitude and spectral distribution of the effects of an eclipse on the upper atmosphere."

From their positions a few hundred miles above Earth's surface, the "hyperspectral" imagers aboard both TIMED and DMSP spacecraft produce images in hundreds of wavelengths by "sweeping" their fields of view. Before information is sent back to the science teams on the ground, it's combined aboard the respective satellites to produce multi-color imagery of the Earth in the far ultraviolet (100-200 nm).

 "These dramatic observations of the eclipse are providing the atmospheric science community with a unique opportunity to study how the Earth's upper atmosphere responds to external changes," Paxton says.

Since its launch in 2001, TIMED has been exploring one of Earth's last atmospheric frontiers, collecting valuable data during various phases of the solar cycle. It's part of the Heliophysics Great Observatory — a collection of NASA's sun-Earth-focused missions. For more information, visit http://www.timed.jhuapl.edu.

For more information about the DMSP satellites, visit http://heasarc.nasa.gov/docs/heasarc/missions/dmsp.html.

 

Click on the thumbnail image for a larger (300 dpi) version or link below to view the video clip.

View the video clip


The Applied Physics Laboratory (APL) is a not for profit laboratory and division of The Johns Hopkins University. APL conducts research and development primarily for national security and for nondefense projects of national and global significance. APL is located midway between Baltimore and Washington, D.C., in Laurel, Md. For information, visit www.jhuapl.edu.