There be a solar eclipse visible across many regions of North America, on Monday, August 21. The total eclipse will be visible in a swath from Portland, Oregon to Charleston, South Carolina. Outside that swath, observers may be to see a partial eclipse.
As HF operators well know, solar radiation plays a major role in signal propagation. There is an effort to measure the changes in propagation when the eclipse occurs. See: February 2017 QST magazine, page 82, or August 2017 QST magazine, page 94 for more details. Also: HamSCI.org, HamSCI.org/2017 Total Solar Eclipse, NASA Eclipse Page, or ARRL.org News CEDAR — Coupling, Energetics, and Dynamics of Atmospheric Regions .
There is a Solar Eclipse QSO Party on that date, associated with the effort to measure the effects on propagation. See the above sources for more information, or HamSCI.org/seqp