Total Lunar Eclipse. Discussion
by Forrest Brown.
Despite the call for clouds last Wednesday many people turned out to
view the complete lunar eclipse, a phenomenon only possible during the
full Moon, when the Earth comes between the Moon and the Sun. This
picture shows the completely eclipsed Moon. The Moon
entered the Earth's shadow, becoming a reddish hue. This coloring is
caused by the absence of the shorter wavelengths of light, such as
blue. The blue light is scattered as it tries to penetrate the
Earth’s atmosphere. Only the longer red light wavelengths are able to
completely penetrate the Earth’s atmosphere and reach the Moon.
See diagram below.
picture at left shows the Moon as it begins to enter the Earth's
shadow. The shadow of the Earth’s curve can be seen on the Moon
as it obscures the Sun’s light. Here the moonlight appears normal
because the full spectrum of sunlight is reaching it. The Earth has yet
to fully block the Moon.
the Moon begins to emerge from the Earth’s shadow. In the
picture at right it can be seen that the bottom of the Moon is emitting
the full spectrum of light, while the rest is still illuminated by only
red light wavelengths. This picture was taken at a longer exposure so
that the dark eclipsed portion of the Moon is visible, unlike the
Photo of the
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature an interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to firstname.lastname@example.org.