Cite
 

Meaning of active sun

ac'tive sun'

Pronunciation: [key]
— Astron. Astron.
  1. the sun at a maximum of solar activity, occurring every 11 years.
  2. solar activity, superimposed on an unchanging background. Cf. quiet sun, solar cycle.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.