The ashen light was first observed by Giovanni Riccioli on 9 January 1643 and is believed to be an optical illusion by some astronomers, though others believe it to be caused by electrical storms in Venus's atmosphere.
The ashen light was first observed by Giovanni Riccioli on 9 January 1643. Some astronomers believe it is an optical illusion brought about through relatively poor optics, others think it may be caused by electrical storms in Venus's atmosphere.