This is the post from Palmerston North Astronomical Society. As always the explanations as to why things happen are really good!
AURORA ALERT! I don’t normally do this as aurora predictions can be as off as terrestrial weather predictions sometimes. That is not the case for tonight. Over the past few days a huge active sunspot group has been firing off solar flares and their associated CME’s (Coronal Mass Ejections). No less than five CME’s are headed for the Earth (one hit this morning before dawn N.Z. time). They are coming to us at different speeds (measured in km’s/second). The higher the wind speed, the greater chance for us to see an aurora. There are other factors that increase our chances of seeing an actual auroral display. One of the components relating to the Earth’s magnetism we call the Bz. When the Bz swings to the south, with a negative sign, we are almost certain to see aurorae. The great thing about this event is that one of the later CME’s is travelling faster than the earlier ones and is catching up to them and consuming them. We call these ones, “Cannibal CME’s.” The great thing about the ‘Cannibals’ is that they are strongly negative! The scientists predict that the strongest period could be from 6pm to 9pm tonight local time. In reality this storm could go on all night. If you live in a town or the city find somewhere south or in whatever direction that doesn’t have urban lights in the distance along the southern horizon. On an average day the solar wind speed can bee around 300km/sec. At the moment it is 730km/second! Wishing you clear skies and a lot of luck wherever you are!
