SUN-EARTH CONNECTION: Even a small solar flare can reach out and touch the Earth. On April 16th, sunspot 1190 produced a relatively minor C5-class flare. X-rays from the distant explosion broke apart molecules in Earth's upper atmosphere, creating a wave of ionization over Europe. Researcher Rob Stammes detected the sudden ionospheric disturbance or "SID" using a very low frequency radio receiver at the Polar Light Center in Lofoten, Norway:
[link to spaceweather.com]
The wave of ionization allowed signals from a terrestrial radio station to bounce over the horizon into Stamme's 23.4 kHz VLF antenna. That's what's shown in the upper panel. Now consider the lower panel: "There was also a small increase in radio noise directly from the flare itself at 56.25 MHz," points out Stammes. "Contact with the sun at VLF and VHF radio frequencies at the same moment gives me important information."