A HOLE IN THE SUN’S ATMOSPHERE: jagged hole in the sun’s atmosphere is facing Earth and spewing a stream of solar wind toward our planet. Estimated time of arrival: Sept. 17th. Because the gaseous material will reach Earth only a few days before the onset of northern autumn, it may be extra-effective at sparking auroras–a result of “equinox cracks” in the geomagnetic field. Free: Aurora Alerts

Equinox cracks in Earth’s magnetic field may have helped the solar wind penetrate deeper than usual. If so, more nitrogen auroras could be in the offing. The actual equinox is less than a week away, and a new stream of solar wind is approaching Earth. ETA: Sept. 17-18. Stay tuned for pink. Free: Aurora Alerts