Hackaday Links: January 23, 2022

When Tonga’s Hunga-Tonga Hunga-Ha’apai volcano erupted on January 15, one hacker in the UK knew just what to do. Sandy Macdonald from York quickly cobbled together a Raspberry Pi and a pressure/humidity sensor board and added a little code to create a recording barometer. The idea was to see if the shock wave from the eruption would be detectable over 16,000 km away — and surprise, surprise, it was! It took more than 14 hours to reach Sandy’s impromptu recording station, but the data clearly show a rapid pulse of increasing pressure as the shockwave approached, and a decreased pressure as it passed. What’s more, the shock wave that traveled the “other way” around the planet was detectable too, about seven hours after the first event. In fact, data gathered through the 19th clearly show three full passes of the shockwaves. We just find this fascinating, and applaud Sandy for the presence of mind to throw this together when news of the eruption came out.


Good news for professional astronomers and others with eyes turned skyward — it seems like the ever-expanding Starlink satellite constellation isn’t going to kill ground-based observation. At least that’s the conclusion of a team using the Zwicky Transient Facility (ZTF) at the Palomar Observatory outside San Diego. ZTF is designed to catalog anything that blinks, flashes, or explodes in the night sky, making it perfect to detect the streaks from the 1,800-odd Starlink satellites currently in orbit. They analyzed the number of satellite transients captured in ZTF images, and found that fully 20 percent of images show streaks now, as opposed to 0.5 percent back in 2019 when the constellation was much smaller. They c ..

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