The disk blocks the bright glare of the Sun to reveal the fainter corona . I have published pictures of October 9th full-halo solar flare on the web site. SOHO is a unique satellite operating from a permanent vantage point 1.5 million kilometers ahead of the Earth in a halo orbit around the L1 Lagrangian point . SOHO Will observe the Sun continuously for at least two years. The signal loss occurs in areas of Earth facing the Sun.
Geomagnetic storms can cause electrical components to fail in the power grid and damage satellites.
Long distance radio communications depend heavily on refraction of radio waves by the ionosphere. It is primarily the bounce or number of bounces that gives distance to HF radio signals. The increase in x-rays produced by a solar flare is detectable on Earth in less than 8 minutes. A PCA occurs when cosmic rays penetrate deeply into the ionosphere over the poles. HF signals between 160 meters and 10 meters are heavily effected by these conditions.