Red Moon Rising
February 2, 2000 -- On January
20, 2000, the full moon plunged into the darkest part of Earth's
shadow and put on a beautiful show for sky watchers from Europe
to Hawaii.
"Hey, you were right, there really is an eclipse,"
exclaimed an amazed 8-year old observer in windy St. Louis, Missouri.
"This is awesome!"
To that young sky watcher, the sight of the Earth's shadow taking
a bite out of the brilliant lunar disk banished thoughts of the
cold and transformed the night sky into something dynamic and
spellbinding. It was also much-needed proof that his uncle (the
author) was a genuine astronomer. As we craned our necks for
a better view of the Moon, everyone in our little party of star
gazers agreed that the eclipse was well worth the discomfort
of a freezing winter breeze.
Less than an hour later the entire lunar disk was tinged with
an eerie copper color. The surrounding stars, which were lost
in the brilliant glare of moonshine earlier that evening, twinkled
brightly in the crisp, clear mid western sky.
Right: These digitally superimposed
photographs were captured by Stephen Barnes during the January
20, 2000 lunar eclipse. There are three exposures: one just as
the Moon entered the Earth's shadow (top), once when the Moon
was near the middle of the shadow, and once just before the Moon
exited (middle). [more
information]
Blue Sky, Red Moon
For many observers, the most striking aspect of the eclipse
was the Moon's reddish hue during totality. During an eclipse,
when the Moon is in Earth's shadow, there is a little bit of
sunlight that passes through our atmosphere. White light from
the sun is composed of all the colors of the rainbow, but our
atmosphere treats different colors differently. Blue-colored
light is scattered in all directions by airborne molecules. This
is the same phenomenon that causes our sky to be blue. Red-colored
light, on the other hand, is scattered very little. However,
it is refracted (bent) inward toward the Moon. Red light that
hits the Moon is reflected back toward Earth, so that we see
the Moon glowing red during totality. If the Earth did not have
an atmosphere, the Moon would be nearly black during a total
lunar eclipse.
Above: When the Earth is situated
precisely between the Sun and the Moon, why isn't the Moon totally
dark? It's because of Earth's atmosphere. The white light from
the Sun is a mixture of all the colors of the rainbow. When a
ray of "white" sunlight passes at grazing incidence
through Earth's atmosphere, molecules in the air scatter the
blue light in all directions (this is why the sky is blue). The
remaining reddish light is bent (refracted) into the Earth's
umbral shadow zone, giving
the eclipsed Moon a coppery glow. [more
information] 
Differing amounts of clouds and volcanic
aerosols in the Earth's atmosphere make each lunar eclipse appear
differently. The 1991 eruption of Mount Pinatubo in the Philippines
filled Earth's atmosphere with particulate matter and aerosols.
As a result, until the air cleared in 1998, every total lunar
eclipse between 1992 and 1997 (there were 6 of them) exhibited
a darker-than-usual red coloration.
Right: This sequence of images was
obtained by Doug Murray, a Science@NASA reader in Palm Beach
Gardens, FL, during the January 20, 2000 total lunar eclipse.
The January 2000 eclipse was the first one since 1993 that was
visible from start to finish across North America. This won't
happen again until December
21, 2010.
If you missed this eclipse, there's another one just around the
corner. On July
16, 2000 observers on the west coast of North America, the
Pacific, Australia and Japan will see a spectacular eclipse with
nearly two hours of totality.
Above: This unusual picture is a
composite of a 2.5 hour exposure and a 2 hour exposure of the
January 20th eclipse using a 1955 Rolleiflex Twins Lens Reflex
120 format camera. Doug Murray, a Science@NASA reader, captured
these images from his front yard in Palm Beach Gardens, Florida.
The Earth's rotation caused the Moon and stars to appear as streaks
during the two exposures. As the Earth's shadow engulfed the
Moon, the Moon streak became less and less bright, practically
disappearing during totality. At this time, the Moon, which normally
shines by reflecting direct sunlight, shone only by sunlight
refracted through the Earth's atmosphere.
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Total Lunacy - Science@NASA article about the first lunar eclipse of the year 2000.
Total Lunar Eclipse: January 20-21, 2000 - a press release from the Goddard Space Flight Center
More information about the eclipse -from Fred Espenak at the Goddard Space Flight Center
Tips for photographing a lunar eclipse -an excellent overview from MrEclipse.com
5000 year catalog of lunar eclipses -During the 50 century period, 2000 B.C. to 3000 A.D., Earth experiences 12186 lunar eclipses.