Equinox Cracks Are Opening In Earth's Magnetic Field

The northern autumnal equinox is only two days away. That means one thing. Cracks are opening in Earth's magnetic field. Researchers have long known that during weeks around equinoxes fissures form in Earth's magnetosphere. Solar wind can pour through the gaps to fuel bright displays of Arctic lights. One such episode occurred on September 19. The sky exploded with auroras. During the display, a stream of fast solar wind was grazing Earth's magnetic field. A solar wind stream flowing above 500 km/s has triggered a minor (G1) geomagnetic storm at higher latitudes. But this time of the year even a gentle gust of solar wind can breach our planet's magnetic defenses. This is called the “Russell-McPherron Effect,“ named after the researchers who first explained it. The cracks are opened by the solar wind itself. South-pointing magnetic fields inside the solar wind oppose Earth's north-pointing magnetic field. The two, N vs S, partially cancel one another, weakening our planet's magnetic defenses. This cancellation can happen at any time of year, but it happens with greatest effect around the equinoxes. Indeed, a 75-year study shows that months around Equinoxes are the most active months of the year, a direct result of “Equinox Cracks.“ Small ones are about the size of California, and many are wider than the entire planet. While the cracks are open, magnetic fields on Earth are connected to those on the Sun. Theoretically, it would be possible to pick a magnetic field line on terra firma and follow it all the way back to the solar surface. There's no danger to people on Earth, however, because our atmosphere protects us, intercepting the rain of particles. The afterglow of this shielding action is called the “Aurora Borealis.“ #equinoxcracks #solarwind #aurora Images credit: nemesis maturity channel, NASA, ESA, Music credit: YouTube Audio Library Lazy Laura - Quincas Moreira