Spotless Sun, Coronal hole

Saturday, 18 March 2017 17:03 UTC

...and guess what... its our lucky day today as we have a very nice coronal hole facing our planet today!

A coronal hole is facing Earth. Enhanced solar wind could arrive in ~3 days - Follow live on https://t.co/T1Jkf6i4Cb pic.twitter.com/9VPyIsb78x

— SpaceWeatherLive (@_SpaceWeather_) March 18, 2017

Its a familiar solar feature as we have seen this coronal hole before. A quick look into our ever expanding archive (yes that is indeed a teaser) reveals that this coronal hole changed a quite a bit since the last time it faced our planet almost one month ago. While the extension west of the main opening seems to have closed up quite a bit, the main opening has increased in size and that is great news for us sky watchers. Larger coronal holes in general provide us with a faster solar wind stream that pushes a stronger Co-rotating Interaction Region (CIR) ahead of the stream. For those who think that was incomprehensible gibberish: bigger coronal holes often cause more aurora than small coronal holes! Who would have thought!

The solar wind stream should take about three days to arrive at our planet which gives us an estimated arrival on 21 March. The NOAA SWPC has not yet issued a geomagnetic storm watch but we think minor G1 geomagnetic storm conditions are likely on 21 and perhaps 22 of March. Well worth the effort to keep an eye on the real-time solar wind data in the days ahead!