On August 21, almost entire United States witnessed its first total solar eclipse in 99 years. During the eclipse, the moon completely blocked the light of the sun and plunged many places into the darkness in the midday.
However, the August solar eclipse did more than just give viewers a cosmic show on the ground. It not only casted a shadow on our planet but also generated bow waves in the Earth’s upper atmosphere.
Bow waves are mysterious ripples. They are similar to the waves created by the bow of a ship when it moves through the water. The waves are attributed to sudden change in temperature during solar eclipse. As the moon travels between the sun and Earth, its shadow blocks the sun's energy and rapidly cools the area beneath it.
The hypothesis that a solar eclipse would produce bow waves in the upper atmosphere emerged in 1970 but it never adequately measured or demonstrated until now.
When Moon's cool shadow swept across the United States in August’s solar eclipse, it moved with supersonic speed through the Earth's atmosphere. The movement was so quick it created waves in the Earth’s atmosphere.
“We were looking at some phenomena that were expected but never had the chance to be observed. That was the surprise we found... we had a large coverage and our system is sensitive enough to be able to see these smaller variations. That was really very interesting to us.” Study author Shun-Rong Zhang from the MIT Haystack Observatory told Gizmodo.
To investigate, MIT researchers used a large network of about 2,000 satellites placed across North America. The data collected from the satellites provided the evidence of tiny bow waves in Earth’s ionosphere, which is located about 37 miles above the surface. The bow waves moved mostly at the speed of 670 mph and lasted for about 1 hour. But they were not intense enough to have any negative effects on systems.
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Hira Bashir covers daily affairs around the world.