For a few hours on the night of Dec. 20-21, the attention of tens of millions of people will be drawn skyward, where there will hang a mottled, coppery globe—our moon—completely immersed for a while in the long, tapering cone of shadow cast out into space by our earth. If the weather is clear, favorably placed sky watchers will have a view of one of nature's most beautiful spectacles: A Total Eclipse of the moon.

Unlike a total eclipse of the sun, which often requires a long journey to the path of totality, those of the moon can usually be observed from one's own backyard. The passage of the moon through the Earth's shadow is equally visible from all places within the hemisphere where the moon is above the horizon.

The total phase of the upcoming event will be visible across all of North and South America, as well as the northern and western part of Europe, and a small part of northeast Asia including Korea and much of Japan. Totality will also be visible in its entirety from the North Island of New Zealand and Hawaii—a potential viewing audience of about 1.5 billion people. This will be the first opportunity from any place on earth to see the moon undergo a total eclipse in 34 months.

Stages of the Eclipse

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.

The eclipse will actually begin when the moon enters the faint outer portion, or penumbra, of the earth's shadow a little over an hour before it begins moving into the umbra. 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 faint "smudge" on the left part of the moon's disk at or around 1:15 A.M. Eastern Time or 10:15 P.M. Pacific Time (on Dec. 20).

The most noticeable part of this eclipse will come when the moon begins to enter the earth’s dark inner shadow (called the umbra). A small scallop of darkness will begin to appear on the moon's left edge at 1:33 A.M. Eastern Time or 10:33 P.M. Pacific Time (on Dec. 20).

The moon is expected to take 3 hours and 28 minutes to pass completely through the umbra.

The total phase of the eclipse will last 72 minutes beginning at 2:41 A.M. Eastern Time or 11:41 P.M. Pacific Time (on Dec. 20). At the moment of mid-totality (3:17 A.M. Eastern Time/12:18 A.M. Pacific Time), the moon will stand directly overhead from a point in the North Pacific Ocean about 800 miles (1,300 km) west of La Paz, Mexico.

The moon will pass entirely out of the earth's umbra at 5:01 A.M. Eastern Time/2:01 A.M. Pacific Time and the last evidence of the penumbra should vanish, about 15 or 20 minutes later.

Only the Shadow Knows the Moon’s Color

Although astronomers do not expect to gain new astronomical insights from the eclipse, lunar eclipses vividly reflect the overall state of the earth’s atmosphere. Under normal weather and atmospheric conditions, as the moon slides into the shadow of the earth, its normal yellow-white color changes into a still-visible but dull coppery-red at the height of the eclipse. Since the earth's shadow is cone-shaped and extends out into space for some 844,000 miles (1,358,000 km), sunlight will be strained through a sort of “double sunset,” all around the rim of the earth, into its shadow and then onto the moon.

However, because of the recent eruptions of the Mt. Eyjafjallajökull volcano in Iceland last spring and the Mt. Merapi volcano in Indonesia in October, one and possibly two clouds of ash and dust might be currently floating high above the Earth. As a result, the moon may appear darker than usual during this eclipse; during totality, parts of the moon might even become black and invisible.

Or . . . the moon might wear its normal eclipse cloak of a deep red or a coppery-hue or take on still other colors (orange, chocolate brown or gray). Color possibilities are unpredictable and that it is impossible to tell exactly how much light the earth’s atmosphere will refract as its shadow creeps across the moon. Cloud cover and other atmospheric conditions may also affect the visibility and coloration of the Moon.

In short: we’ll all just have to wait for eclipse night and see what actually happens.

At mid-totality, from rural locations far from city lights, the darkness of the sky is impressive. Faint stars and the Milky Way will appear, and the surrounding landscape will take 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.

Past and Future

The last total lunar eclipse occurred on Feb. 20-21, 2008 and was visible from most of the Americas, as well as Europe, much of Africa and western Asia. In 2011 there will be two total lunar eclipses. The first, on Jun. 15 will be visible primarily from the Eastern Hemisphere and will have an unusually long duration of totality lasting one hour and 40 minutes. Another total lunar eclipse will occur on Dec. 10 and will be visible over the western half of North America before moonset. For the next total lunar eclipse that will be visible across all of North America, we must wait until Apr. 14-15, 2014.

A good friend of mine, Joel Moskowitz of Long Island is (like me) hopelessly addicted to traveling anywhere in the world to view a total eclipse of the Sun. On Friday, August 1, I saw my tenth eclipse, but Joel is two ahead of me with 12.  And every time totality ends, Joel always says the same thing:

Let's do it again!

I joined 146 observers from around the world for a perfect view of the August 1st total eclipse, thanks to an 2,189-mile airlift to a grandstand seat 36,000-feet above the Arctic Ocean at a point between the uninhabited northern coast of Greenland and the Norwegian island group of Svalbard.

The contingent of eclipse watchers were onboard an Airbus A330-200 long-range jet, racing the moon's shadow like paparazzi scrambling alongside a celebrity's passing automobile. The aircraft's 555-mile-per-hour speed (Mach 0.85) provided 175-seconds of total eclipse for all onboard passengers to take pictures and record other data.  In contrast, persons on a stationary ship on the Arctic sea below would have seen—provided no clouds blocked the view—the moon's 139-mile wide shadow speed past them at 2,740 mph, providing a noticeably shorter total eclipse lasting 132 seconds.

No planetarium in the world could have produced so impressive a natural spectacle as the sun and moon did in the cobalt-blue heavens; although the sight lasted less than 3 minutes, the fantastically beautiful skyscape more than repaid all of us; in fact we had to be up before dawn to ready ourselves for a round-trip flight of 12 hours.

The adventure began nearly six hours earlier in Dusseldorf, Germany and was arranged by the air charter company Deutsche Polarflug (AirEvents) which has operated previous successful over-flights of the North Pole with this same aircraft. Dr. Glenn Schneider, from the University of Arizona's Steward Observatory, on hand for his 27th total eclipse, worked out the flight plan to rendezvous with the moon's shadow. Glenn and I grew up in the Bronx and we've known each other for 35-years.

The flight itself was unique in the annals of solar eclipse chasing since there were no other records of any total eclipse observations in such close proximity (approximately 500-miles) from the North Pole.  Utilizing Glenn's data, Captain Wilhelm Heinz, maneuvered the aircraft into the track of the moon's dark shadow.  Our jet, surmounted more than 75-percent of the atmosphere (in terms of mass) and almost all of its water vapor below, providing an opportunity to see what happens in the Earth's upper atmosphere when the sun is switched off, so to speak. Minutes before totality, the light inside the cabin faded, much in the same manner as lights in a theater dim before the start of a show.

As the last of the sun's rays slipped behind the jagged lunar edge it produced a beautiful and long-lasting Diamond Ring effect. The dark lunar shadow then swept in from the west and enveloped the plane in an eerie darkness.  The sun's beautiful corona heralded the beginning of the total phase.  It appeared to throw off several long streamers—typical for a corona at sunspot minimum, which is where solar activity is now.

Adding to this scene was an array of four bright planets arranged to the lower left of the darkened sun: Mercury, Venus, Saturn and Mars.  Some of us searched near the sun for a small, faint comet that was discovered on satellite imagery some hours before the eclipse.  But no evidence of it was observed.

Glenn's experiments dealt in part with the density of plasma within the solar corona, and especially how it is heated to millions of degrees. Plasma is a gas in which normal atoms have been stripped of some or all of their electrons, thus becoming ions.  This commonly occurs in extremely hot gases such as the solar corona.  The plasma in the corona is strikingly similar to the plasma that would have to be heated, compressed and refined in a fusion reactor here on Earth, and the irregular behavior of the sun's corona might hold clues to the proper design of a workable fusion reactor.

Glenn was collaborating with Jay Pasachoff of Williams College in Massachusetts who was stationed in Siberia for the eclipse.  He utilized a platform controlled by two gyros that carried several cameras for recording eclipse images.  They previously collaborated on a similar observation over the Antarctic in 2003.

After the eclipse, Captain Heinz flew our aircraft to a point directly above the North Pole, then we headed back to Dusseldorf.

On Saturday, August 2nd (my birthday), I headed back to New York. Unfortunately, I arrived more than 4-hours late after having my flight from Germany re-routed first (unsuccessfully) to Boston and then to Bangor, Maine.  We sat on the tarmac for an hour while they refueled the plane.  Then, we headed back to JFK.  Apparently, extensive delays in the wake of thunderstorms from earlier in the day was the reason for our unscheduled detour to New England.  Most of the folks onboard the plane were German and had no clue where Bangor was.  The guy who was next to me spoke pretty good English and so he served as a translator for most of the people sitting around us as I explained that Bangor was a city much smaller than Boston, located about 250 kilometers farther away to the north and east.  There was a nervous murmur in the crowd and then one guy commented: Mit dieser et uns zurück zu Deutschland! (At this rate, they'll be sending us back to Germany!).

I was on that plane for 12-hours; and the day before I was on the Eclipse Flight, also for 12-hours!  The next total solar eclipse will be on July 22nd of next year and will sweep across India, China and the south islands of Japan.  You might wonder if all the time and miles expended is worth a view of a darkened Sun for a few precious minutes?

My answer?

Let's do it again!