Page:The ocean and its wonders.djvu/201

 brilliancy of the spectacle that is occasionally presented in the northern skies.

The most ordinary aspect of the aurora is that of a band of pale-green light extending irregularly over part of the sky, and marked by wavy motions, as well as by varying brightness. Sometimes one



part of this band becomes more bright than another part. Sometimes the whole seems to move gently, like the undulations of a flag in a light breeze; at other times more vigorous action takes place, and pointed tongues of light shoot vividly up into the