Eclipse Created Atmospheric Bow Waves.
Although the "Great American Eclipse" is now many months behind us, we're still learning about the effect of the Moon's shadow on the ionosphere, electrified layers of the atmosphere 80 to 1,000 km (50 to 600 miles) above the ground. Ultraviolet sunlight breaks apart molecules to create these layers, so when the Sun disappears (such as at nighttime), the layers decrease or disappear altogether. Last summer's eclipse provided the first opportunity to track the effects of the Moon's shadow as it raced across the continental U.S., as reported in the January 19th Geophysical Research Letters. Shunrong Zhang (MIT Haystack Observatory) and colleagues observed the ionosphere using 2,000 GPS receivers across the nation. The receivers communicated with satellites to provide high-resolution data on the total electron content of the ionosphere. Because the Moon's shadow moved upersonically across Earth's surface, the disturbances in electron content that it created generated ionospheric bow waves, which were observed most clearly over the central and eastern U.S. Watch the bow waves at https://is.gd/eclipsebow.
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|Publication:||Sky & Telescope|
|Article Type:||Brief article|
|Date:||May 1, 2018|
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