WASHINGTON: When a rare total solar eclipse sweeps across North America on Monday, scientists will be able to gather invaluable data on everything from the Sun's atmosphere to strange animal behaviours — and even possible effects on humans.
It comes with the Sun near the peak of its 11-year solar cycle, setting the stage for a breathtaking display: The corona will glow spectacularly from the Moon's silhouette along the path of totality, a corridor stretching from Mexico to Canada via the United States.
Total solar eclipses offer "incredible scientific opportunities," Nasa Deputy Administrator Pam Melroy told a press conference this week about the celestial event.
The US space agency is one of the institutions at the ready for the eclipse, with plans to launch so-called "sounding rockets" to study the effects on Earth's upper atmosphere.
When the Moon passes directly in front of the Sun and blocks it, the elusive outermost edge of the Sun's atmosphere, or corona, will be visible "in a very special way," Melroy said.
"Things are happening with the corona that we don't fully understand," she said.
The heat within the corona intensifies with distance from the Sun's surface — a counterintuitive phenomenon that scientists struggle to fully comprehend or explain.
Solar flares, a sudden explosion of energy that releases radiation into space, take place in the corona as do solar prominences, enormous plasma formations that loop out from the Sun's surface.
During an eclipse, the bottom most part of the corona — where a lot of this activity occurs — is more clearly visible than when using specialised instruments to block the central part of the Sun, offering a golden opportunity for study, said Shannon Schmoll, director of the Abrams Planetarium at Michigan State University.
Researchers are particularly thrilled about the Sun being near the peak of its 11-year cycle.
"The chance we're going to see something amazing is very high," Melroy said.
The total eclipse also will afford scientists a chance to study changes in part of the Earth's upper atmosphere known as the ionosphere, important because it affects radio waves used for communication and navigation.
"Disturbances in this layer can cause issues with GPS and communications," said Kelly Korreck, the eclipse programme manager at Nasa headquarters.
The ionosphere, which is where Earth's atmosphere meets space, is affected by the Sun, which electrically charges the particles there during the day.
Nasa's three sounding rockets will be launched before, during and just after the eclipse from Virginia to measure these changes. The major decrease in sunlight provoked by the eclipse —more rapid and localised than a simple sunset — should allow researchers to learn more about how light affects the ionosphere so they can better predict potential problematic disruptions. — AFP
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