Earth's Shadow in Red Light
November 30, 2013
The photo above shows a view near Tornquist, Argentina, using a filter sensitive to the 720 nm region (red light) of the electromagnetic spectrum. This is the far-end of the visible spectrum -- wavelengths are longer here than in the green or blue portions of the spectrum. The camera is looking toward the eastern horizon just after sunset. Note the blue-fringed strip of sky between the two hill slopes at center. This is known as the Belt of Venus. Our eyes, which utilize the entire visible spectrum (from about 375-750 nm), sees this band in pinkish hues. The dark wedge below the Belt of Venus is the edge of night -- the rising Earth's shadow. Healthy vegetation appears white here since chlorophyll is reflective in red light. The photo at left shows that, even in winter, the Argentinian plains are always green. It was taken on July 5, 2013, the same day and at the same location as the above photo.
Photo details - Inset: Camera Model: Canon EOS 6D; Aperture: f/0.0; Exposure Time: 0.017 s (1/60); ISO equiv: 1600.