... Shadow Cone of a Total Solar Eclipse . ... Credit: Oliver Staiger ( High Moon ) Explanation: Sometimes, during a total eclipse of the Sun, a strange shadow of darkness can be seen stretching off into the distance. Called a shadow cone, they are visible because the Earth's atmosphere is not completely transparent, scattering sunlight and hence appearing blue during the day. ... Visible above is a shadow cone caught during a total solar eclipse visible last month from South Australia . ...