According to SpaceWeather.com, one of the sunspot groups is associated with an unstable magnetic field, which increases the odds of a solar flare. Already, a stream of high-speed solar wind thrown off the sun this weekend is expected to reach Earth on July 18—exactly the kind of activity that can spark auroras.

Any geomagnetic storm triggered by this event is most likely to be minor, with auroras visible only at high latitudes late on July 18 and 19. Southern Hemisphere sky-watchers with their long winter nights may be best placed for the potential light show.

The July full moon has taken on many traditional names in North America, according to the Old Farmer’s Almanac. It’s sometimes called the thunder moon,