In August 2017 the “Great American Eclipse” crossed the Pacific Ocean and the continental United States. Most Americans witnessed a spectacular view but MIT a few scientists witnessed much more.
MIT researchers found that the moon’s shadow created long-predicted ionospheric bow waves during the August eclipse.
Researchers at MIT’s Haystack Observatory and the University of Tromsø in Norway were able to observe the eclipse bow wave phenomenon for the first time in the atmosphere with unprecedented detail and accuracy thanks to the vast network of extremely sensitive GNSS receivers now in place across the U.S.
The observed ionospheric bow waves are much like those formed by a ship; the moon’s shadow travels so quickly that it causes a sudden temperature change as the atmosphere is rapidly cooled and then reheated as the eclipse passes.
“The eclipse shadow has a supersonic motion which [generates] atmospheric bow waves, similar to a fast-moving river boat, with waves starting in the lower atmosphere and propagating into the ionosphere,” said MIT researcher Shunrong Zhang. “Eclipse passage generated clear ionospheric bow waves in electron content disturbances emanating from totality primarily over central/eastern United States. Study of wave characteristics reveals complex interconnections between the sun, moon, and Earth’s neutral atmosphere and ionosphere.”
These findings are important because they advance theoretical understanding and address a long-standing controversy surrounding one of nature’s most spectacular active events.
Haystack scientists will continue to analyze recorded data from the eclipse and expect to report other findings soon. The next major eclipse across North America will occur in April 2024.