Thursday 29 March 2018

AR12699 - Return of the Plage: Take 2

 When you look at the SDO image above you might be fooled into thinking something big is coming around the solar limb near the solar equator (left hand side).  Sadly this is just the remnants of AR12699 from February, and all that will be visible now is some decaying plage, visible in CaK wavelengths, and possibly discernible in Ha wavelengths.  For most people this will go totally un-noticed.  It should be visible on the LASP solar irradiance plot as a slight up tick in the graph as the slightly brighter plage rounds the limb.  When sunspots are visible the opposite effect happens with a trough or down tick in the graph as the cooler, darker sunspots actually reduce the total solar irradiance as they pass over the Earthward face of our star.  Will be interesting to see over the Easter fortnight how visible this relic plage actually is.