June 06, 2012

Visible and invisible

This is a picture of earth from moon (source).  What I find interesting in this is that it’s all pitch-dark around earth.  But space on at least one side of earth must be filled with sunlight.
If we cannot see anything, it’s not always because there’s no “light”... sometimes it’s because there’s no dark, light-reflecting object.  In other words, all we see is contrast.

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