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<\/p>\nDR.TONY PHILLIPS<\/p>\n
<\/p>\n
April 21, 2023:<\/strong>\u00a0Earth is in the strike zone. On April 21st, a large magnetic filament snaking across the sun\u2019s southern hemisphere exploded, hurling a cloud of debris in our direction. This movie from NASA\u2019s Solar Dynamics Observatory shows what happened:<\/p>\n Soon after the eruption, the US Air Force reported strong Type II and Type IV solar radio bursts. These are natural shortwave emissions produced by shock waves preceding the CME as it passes through the sun\u2019s atmosphere. Drift rates in the Type II burst suggested a CME velocity of about 580 km\/s (1.3 million mph).<\/p>\n Images from SOHO coronagraphs have since confirmed the CME. It is a \u201chalo CME\u201d heading straight for Earth:<\/p>\n Models\u00a0from NASA<\/a>\u00a0and\u00a0from NOAA<\/a>\u00a0agree: the CME should reach Earth during the early hours of April 24th between the hours of 00:00 and 12:00 UT. The impact could spark\u00a0G1-<\/a>\u00a0(Minor) to\u00a0G2-class<\/a>\u00a0(Moderate) geomagnetic storms, with a slight chance of\u00a0G3<\/a>\u00a0(Strong).\u00a0Aurora alerts:<\/strong>\u00a0SMS Text<\/a>.<\/p>\n A BURST OF STATIC FROM THE SUN:\u00a0<\/strong>The explosion that hurled a CME toward Earth on April 21st also illuminated our planet with an intense burst of shortwave radio static. Amateur astronomer Thomas Ashcraft of New Mexico recorded the outburst:<\/p>\n \u201cFew solar radio bursts show as hot purple on my spectrograph, but this one \u2018rang the bell\u2019,\u201d he says. \u201cHere is an audio recording<\/a>\u00a0in stereo with 22 MHz in one channel and 19 MHz in the other.\u201d<\/p>\n The static in Ashcraft\u2019s recording, which washes over the listener like a slow ocean wave, is naturally produced. Astronomers classify it as a\u00a0Type V solar radio burst<\/a>\u00a0caused by energetic beams of electrons ray-gunning through the sun\u2019s atmosphere. The electrons were accelerated by the same underlying explosion that hurled a CME toward Earth.<\/p>\n Solar radio bursts are an underappreciated form of space weather. We often talk about radio blackouts, which happen when solar flares ionize the top of Earth\u2019s atmosphere. A radio blackout suppresses the normal propagation of terrestrial radio signals. Solar radio bursts, on the other hand, produce a radio\u00a0drown<\/em>out. Intense static from the sun overwhelms normal transmissions, drowning out the voices radio operators are trying to hear.<\/p>\n Solar radio bursts will happen more and more often as Solar Cycle 25 intensifies. You can hear them youself using a\u00a0RadioJOVE<\/a>\u00a0radio telescope kit<\/a>\u00a0from NASA.<\/p>\n![\"\"](\"https:\/\/spaceweather.com\/images2023\/21apr23\/filament_anim_purple.gif\")
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![from NASA<\/a>\u00a0and\u00a0](\"https:\/\/spaceweather.com\/images2023\/21apr23\/nasamodel.gif\"){kind=link}
![G1-<\/a>\u00a0(Minor) to\u00a0](\"https:\/\/spaceweather.com\/glossary\/g1.jpg\"){kind=link}
![G2-class<\/a>\u00a0(Moderate) geomagnetic storms, with a slight chance of\u00a0](\"https:\/\/spaceweather.com\/glossary\/g2.jpg\"){kind=link}