Web Iridescence

July 07, 2010

Web iridescence

Photographer: John Adam; John’s Home Page
Summary Author
: John Adam

July 2010 Earth Science Picture of the Day Viewer's Choice

This picture of a carefully constructed spider web was taken in Washington Oaks Gardens State Park, Flagler County, Florida. It was about 10 inches (25 cm) in diameter and exhibited greenish and pink iridescence when the viewing angle was “just right.” Depending on where I stood, I could see more pinks than greens, or vice versa. The thinly spun web acts as a type of circular diffraction grating, each thread being about the right diameter (several microns or less) to diffract (or “deflect”) sunlight. Such threads are also of interest to the photonics industry. Notice also the central “hole” where the spider sits has only radial threads; only the transverse threads are sticky, so the spider can easily apprehend any unfortunate prey by a rapid radial maneuver! Photo taken in May of 2010.

Photo details: Camera Maker: OLYMPUS IMAGING CORP.; Camera Model: SP570UZ; Focal Length: 55.0mm; Aperture: f/4.6; Exposure Time: 0.010 s (1/100); ISO equiv: 200; Exposure Bias: none; Metering Mode: Matrix; Exposure: Creative Program (based towards depth of field); White Balance: Auto; Flash Fired: No; Color Space: sRGB