Mark Megahan
You may be old enough to remember “flash cubes,” attached to Instamatic cameras – seemingly only to provide that “red eye” effect. What just happened on the sun is a lot like what happens if you hurl and skip one of those cubes down a street, like stones on a pond. If you’ve never experienced the thrill, all four bulbs of magnesium trigger at once. Us boomers were lucky to survive childhood but kids today are terrified to drink from a hose.
Brightest flash ever
A flash of light on the sun might not seem like a big deal to most folks but astronomers are going spastic over what they just observed.
Mehr Un Nisa, a postdoctoral research associate at Michigan State University, has been leading a team of researchers who were thrilled to publish a startling study. She has “identified the highest-energy light ever detected emanating from the sun.”
By “highest-energy light,” what they really mean is “gamma rays.” The light detected was surprisingly “bright.” Far “exceeding scientists’ earlier predictions.”
They noted that at the same instant “the gamma rays were generated, the Sun’s activity was quite calm.” The record breaking flash unleashed a trillion times more energy than sol’s typical visible light, all at once.
Generally, the light which we’re familiar with is emitted at around 1 electron volt worth of energy. The “gamma rays detected by the team had energies of a staggering 1 trillion electron volts.”
Since it’s sort of like watching the food cook in a microwave, they didn’t use anything close to normal instruments to look at the gamma ray burst. That’s how they figured out it wasn’t produced directly by the sun itself, and where the skipping flash cube comes in.
Deflected cosmic rays
High-energy particles like protons, electrons, and atomic nuclei, flinging through the universe like stones, go skipping off the sun’s magnetic field. That kicks them into the cloud of atmospheric gases and sets them off like a flash cube. The burst of gamma rays is enormous.
It’s probably been happening forever but just took a galactic record because we never had the right equipment to see it before. It looks more like a chemical tank farm than a telescope.
Called the High-Altitude Water Cherenkov Observatory or HAWC for short, it’s on the job day and night. “Other ground-based telescopes couldn’t look at the sun because they only work at night. Ours operates 24/7,” Nisa relates. Nobody actually saw the flash.
Sprawling over a large field, 13,000 feet above sea level between two dormant volcano peaks in Mexico, “HAWC is comprised of a network of 300 large water tanks, each filled with approximately 200 metric tons of water.” And light detectors. Gamma rays flinging through Earth’s atmosphere generate “a cascade of secondary particles.” If they’re flinging fast enough, “they emit faint flashes of blue light, known as Cherenkov radiation.”
Inside the tanks, “highly sensitive photomultiplier tubes” capture and record every flash. Running the film backward lets scientists “reconstruct the energy, direction, and nature of the incoming particles.” They’ve been collecting data for more than six years before they happened to notice “a remarkable excess of gamma rays in the solar observations.”
They thought they made a mistake or the equipment was broken. “When we first saw it, we were like, ‘We definitely messed this up. The sun cannot be this bright at these energies,” Nisa recalled. They were floored to find out they didn’t mess up. “It’s making us see things in a different light. Literally.“
