If you have a shortwave radio, you might have heard some unusual sounds this weekend. Big sunspot AR2738 is producing strong bursts of radio static. They sound like ocean surf.
As the electrons slice through the sun’s atmosphere, they generate a ripple of plasma waves and radio emissions detectable on Earth 93 million miles away. Astronomers classify solar radio bursts into five types; Ashcraft’s recording captured a Type III.
“There have been a lot of these sounds over the past week, and they appear to be intensifying now that the sunspot is directly facing Earth,” says Ashcraft.