On Wednesday night, Feb. 20, for the third time in the past year, the
moon will become completely immersed in the Earth's shadow, resulting
in a total lunar eclipse.

As is the case with all lunar eclipses, the region of visibility will
encompass more than half of our planet. Nearly a billion people in
the Western Hemisphere, more than 1.5 billion in Europe and Africa,
and perhaps another half-billion in western Asia will be able to
watch — weather permitting — as the brilliant mid-winter full moon
becomes a shadow of its former self and morphs into a glowing coppery
ball.

Almost everyone in the Americas and Western Europe will have a
beautiful view of this eclipse if bad weather doesn't spoil the show.
The moon will be high in a dark evening sky as viewed from most of
the United States and Canada while most people are still awake and
about.

Total triangle

Moreover, this eclipse comes with a rare bonus. The planet Saturn
(magnitude +0.2) and the bright bluish star, Regulus (magnitude +1.4)
will form a broad triangle with the moon's ruddy disk.

Careful watchers will notice the moon changing its position with
respect to the star and planet as it moves eastward through the
Earth's shadow.

Saturn's position will also depend somewhat on your location. Seen
from North America, the great ringed planet will be 3.5 degrees above
and to the left of the moon's center at mid-totality (3:26 Universal
time February 21st). At the same moment, Regulus will sit just 2.8
degrees above and to the right of the moon.

Some old-time astronomy buffs may remember from 40 years ago a total
lunar eclipse with the moon sitting only about a degree from Spica —
a gorgeous celestial tableau! More recently, in 1996, a totally
eclipsed moon passed within 2 degrees of Saturn.

But this upcoming double event will be the only one of its kind
occurring within the next millennium!

Colors and brightness

There is nothing complicated about how to view this celestial
spectacle. Unlike an eclipse of the sun, which necessitates special
viewing precautions in order to avoid eye damage, an eclipse of the
moon is perfectly safe to watch. All you'll need to watch are your
eyes, but binoculars or a telescope will give a much nicer view.

A careful description of the colors seen on the totally eclipsed moon
and their changes is valuable. The hues depend on the optical
equipment used, usually appearing more vivid with the naked eye than
in telescopes. The French astronomer, Andre Danjon, introduced the
following five-point scale of lunar luminosity ("L") to classify
eclipses:

L = 0: Very dark eclipse, moon almost invisible, especially in mid-
totality.

L = 1: Dark eclipse, gray or brownish coloration, details
distinguishable only with difficulty.

L = 2: Deep red or rust-colored eclipse, with a very dark central
part in the shadow, and outer edge of the umbra relatively bright.

L = 3: Brick red eclipse, usually with a bright or yellow rim to the
shadow.

L = 4: Very bright copper-red or orange eclipse, with a bluish very
bright shadow rim.

Examine the moon at mid-totality and also near the beginning and end
of totality to get an impression of both the inner and outer umbra.

At mid-totality, the darkness of the sky is very impressive. Faint
stars, which were completely washed-out by the brilliant moonlight
prior to the eclipse, become visible and the surrounding landscape
takes on a somber hue. As totality ends, the eastern edge of the moon
begins to emerge from the umbra, and the sequence of events repeats
in reverse order until the spectacle is over.

Unless airborne volcanic aerosols or other unusual atmospheric
effects influence its appearance, the moon's disk should appear
moderately bright, especially right around the beginning and end of
totality. The lower part of the moon will likely appear brightest and
glowing a ruddy or coppery hue, while the upper half of the moon
should look more gray or chocolate in color.

Eclipse schedule

The eclipse will begin when the moon enters the faint outer portion,
or penumbra of the Earth's shadow. The penumbra, however, is all but
invisible to the eye until the moon becomes deeply immersed in it.
Sharp-eyed viewers may get their first glimpse of the penumbra as a
delicate shading on the left part of the moon's disk about 20 minutes
before the start of the partial eclipse (when the round edge of the
central shadow or umbra, first touches the moon's left edge). During
the partial eclipse, the penumbra should be readily visible as a
dusky border to the dark umbral shadow.

The moon will enter Earth's much darker umbral shadow at 1:43 on Feb.
21 by Greenwich or Universal time, which is 8:43 p.m. on Feb. 20 in
the Eastern time zone, 7:43 p.m. Central time, 6:43 p.m. Mountain
time and 5:43 p.m. Pacific time.

Seventy-eight minutes later the moon is entirely within the shadow,
and sails on within it for 51 minutes (about average for a total
lunar eclipse), until it begins to find its way out at the lower left
(southeastern) edge.

The moon be completely free of the umbra by 9:09 p.m. Pacific time or
12:09 a.m. (Feb. 21) Eastern time.

The vaguer shading of the inner penumbra can continue to be readily


from Space.com