The Earth's Shadow at
Sunrise from a Hawaiian Mountain
Forrest M. Mims III
When the sun is just over and below
the horizon near sunrise or sunset, the shadow of the
earth can be observed by looking over the horizon opposite
the sun. In this photograph, the shadow of the earth
is the dark layer in the sky below the pink band, which
is formed by rays of sunlight passing through and being
filtered by the lower atmosphere before they illuminate
the distant sky. The intensity and hue of the pink band
is controlled by aerosols in the atmosphere.
In this example, the atmosphere is
very clear, for the photograph was made at sunrise from
Hawaii's Mauna Loa Observatory on 24 May 2005. The observatory
is on the slope of the giant Mauna Loa volcano, the
world's largest mountain, at an elevation of 3,397 meters
(about 11,140 feet) above the surface of the nearby
Pacific Ocean . The mountain in the foreground is Hualalai,
a 2,521 meter (8,271 feet). Both Mauna Loa and Hualalai
are active volcanoes.
The photograph was made with a 4-megapixel
Pentax Optio 43WR water resistant camera. This camera
has an elapsed time mode, which was used to capture
many sunrises and sunsets from Mauna Loa Observatory
and from sea level for a long-term research project
on the affects of aerosols on twilights.
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