Inkwell: Authors and Artists

    
The twilight photometer measurements are ingenious. It must be a thrill to
see the Tonga Hunga - Tonga Hapiai signal. That was a history-making
eruption.
  

    
Thanks, Emily, for the invitation to participate! My twilight
instruments are based on my original design in 2013 (published in
Make magazine in 2015). My friend Scott Hagerup built my best
instrument using 4 telescopes that look at a very narrow fraction of
the sky (0.27 degree, slightly more than half the diameter of the
sun. Each telescope (1-inch diameter) focuses on a single LED used
as a photodiode, a principle I first described in my LED book in
1973. Last night there was little or no Hunga Tonga signal, which is
not unexpected, since that enormous aerosols cloud is finally
breaking up. But on May 29, I detected two layers of meteor smoke at
96-99 km and 103-111 km. These closely match lidar detected layers
reported in a recent paper. Their composition is iron. The twilight
research is fascinating, for one never knows what will be
discovered. Like water vapor all the way to 80 km!
  

    

Thank you for coming to Inkwell.vue! Fascinating discussion.