Total Lunar Eclipse – December 21, 2010

by Tammy Plotner on December 14, 2010

Want to stay on top of all the space news? Follow @universetoday on Twitter

Both lunar and solar eclipses can only occur when the Earth, Sun and Moon are directly aligned… and that alignment is about to happen just four days before Christmas! While the winter treat of totality will lend itself to North America, many other parts of the world will be able to enjoy a partial eclipse as well. Just remember your time zones and I’ll post specific times and locations just a little closer to the date. Right now, let’s learn more!

What is a partial eclipse or totality? When the Earth’s shadow engulfs the Moon, it is a lunar eclipse which occurs in two phases. The outer shadow cone is called the penumbra and the dark, inner shadow is called the umbra. A round body, such as a planet, casts a shadow “cone” through space. When it’s at Earth, the cone is widest at 13,000 kilometers in diameter, yet by the time it reaches the Moon it has narrowed to only 9,200 kilometers. Considering the distance to the Moon is 384,401 kilometers, that’s hitting a very narrow corridor in astronomical terms!

As a rule of thumb, remember that the Moon moves about its own diameter each hour, so the very beginning of a penumbral eclipse will be difficult to notice. Slowly and steadily, the coloration will begin to change and even inexperienced eclipse watchers will notice that something is different. The Moon will never completely disappear as it passes through the Earth’s umbral shadow cone, either. Thanks to our atmosphere bending the sunlight around us, it scatters the light and refracts the signature red and copper coloration we associate with lunar eclipse. Why? Just the small particles in our air – dust and clouds – the shorter wavelengths of light from the Sun are more likely to be scattered (in this case, red) and that’s what we see. Exactly the same reason sunset and sunrise appears to be red! If you’d like to dedicate a portion of your mind to science, then try judging the eclipse coloration on the Danjon scale. It was was devised by Andre Danjon for rating the overall darkness of lunar eclipses:

L=0: Very dark eclipse. Moon almost invisible, especially at mid-totality.
L=1: Dark Eclipse, gray or brownish in coloration. Details distinguishable only with difficulty.
L=2: Deep red or rust-colored eclipse. Very dark central shadow, while outer edge of umbra is relatively bright
L=3: Brick-red eclipse. Umbral shadow usually has a bright or yellow rim.
L=4: Very bright copper-red or orange eclipse. Umbral shadow is bluish and has a very bright rim.

Now we know what to plan for! Time to get your winter gear ready. Photographing or video taping an eclipse is easy – but remember if you live where it is very cold that your batteries will expire fast – so keep an extra set in a warm place next to your body.

Be sure to check back for specific times and locations here at UT on December 20th… and tell your family and friends about the very special Christmas present that’s coming your way!

Eclipse Images Courtesy of Doug Murray (top), Tom Ruen (bottom) and NASA (center illustration). We thank you!

About 

Tammy is a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.

Jon Hanford December 14, 2010 at 5:06 PM

Tammy, thanks for getting the word out for the upcoming lunar eclipse. The last total lunar eclipse for the continental US was back in February of 2008 & the next won’t occur till April 2014. As usual, Fred “Mr. Eclipse” Espenak has an excellent overview of the upcoming event: http://www.mreclipse.com/LEdata/TLE2010Dec21/TLE2010Dec21.html

Included are lunar eclipse diagrams with the times of various stages of the eclipse, more info on making brightness estimates (using the aforementioned Danjon brightness scale), info on crater timings and how to measure them, and tips on how to photograph the event. All that’s needed now is some cooperation in the weather department.

Note: This total eclipse happens to occur (coincidentally) at nearly the same time as the Winter Solstice, meaning only that the Moon will appear at its maximum northern position in its orbit, nearly overhead for observers near 40 degrees N. latitude.

gopher65 December 14, 2010 at 6:40 PM

Thanks for the article.

Bah, I wish that this was happening at a more convenient time (for me;)). I might get up to snap a few pictures if it isn’t -40 outside that day. Maybe I’ll just go to work 4 hours early.

Tim McDaniel December 14, 2010 at 10:41 PM

No, a eclipse of the Moon is when the Sun passes between the Earth and the Moon.

That’s according to _Science Made Stupid_, an _Airplane!_-quality parody of every bad science popularization article and book you’ve ever seen. It also says that an eclipse of the Sun is when the shadow of the Earth passes over the Sun, and an eclipse of the Earth is when you put your hands over your eyes.

Run December 15, 2010 at 1:55 AM

What is the reason for the variation in coloration of the moon during a lunar eclipse? Is it to do with how close to the core of the umbra the moon comes, or is it to do with the amount of light getting through the atmosphere (due to cloud cover etc)?

ricktheruler December 15, 2010 at 9:34 AM

My Birthday’s December 19, so I’am leaving my reasearch observation

Richardo Brown: Signature installed and instrimented on the Lunar Reconnanse Orbiter C.D. Rom

Observation:
Craters dot the moon’s surface. Materials thrown from impacts that made them centers radial patterns of bright ejecta with scars left over by objects that smashed the earth in our early solar system of the star: Sun. The largest are the impact basins, enormous craters raning up to around (1,553mi) across. Lava flooded the basin floor sometime after titanic collisions formed them, creating the smooth, dark surfaces that the eye grography maps as Marias or Seas. Blocks of rock hurled formed with impacts gathering nd becoming larger made what is called the satelite of planet Earth.

Fissures, domed hills and wrinkling ridges all fissioned togther with ancient volcanic lava and weak gravity formed geological igeious basalt and metamorhic anothosite. The lunar surface is sheathed in regolith, a fine dusty tikite,creared by constant bombardment of astroids, comets, and meteoroids. The geology of the moon was brought back to planet Earth by six crews of Apollo astronants from 1969 to 1972. The rocks and dust were copmpletely dry discovering the moon has no water of itas own. The moon is sometimes bombarded by icy – water rick comets. Most of the cometary water evaporizates into space, but some of it may be trapped as ice in the bottoms of shadowing craters near the lunar polars until a few years ago today the temperature on the moons at it coldest point was -274 degrees.

The highlands of the moon are packed together indicating that these ancient areaswere hit repeatedly by astroids and comets and planetoids, in the violent days of our solar system.

My naming of a few mares (seas ) on the satelitte Moon:

Near side to the planet Earth:

Oceanus Procellarum

Mares: Frigorius, Serenitatis, Imbrium, Tranquilitatis, Crisium, Fecunditatis, Humorum, Nubrium, Nectaris, orientale, Cognitum.

Grography on the United States and European Space Agencies landings on the Moon:

Apollo 11 – Tranquility Base, Ranger 8 – Mare Tranquilitatis, Sureyor 5, Ranger 6, Apollo 16 – Mare Serenitatis, Luna 21,

Mare Crisium: Luna 15, Luna 23, Luna 24. Mare Fecunditatis: Luna 26, Luna 18 Luna 20. Mare Imbrium: Luna 17, Luna 2. Mare Imbrium and Palus Putredinus. Sinus Aestuum: Suveyor 8. Senus Medii: Suveyor 6, Suveyor 4. Oceanus Procellarium: Luna 8, Luna 9, Luna 7, Suveyor 1. Mare Cognitum: Luna 5, Apollo 12, Suveyor 3, Ranger 7. Alphonsus (crater) Ranger 9. Hipporchus and Thophilus 6800 (craters) Tycho : Surveyor 7

Far Side in the dark sideof the Moon: Ioffe( crater) Ranger 4. Apollo, Mendel, Lyman, Von Karman, Mare Korolev, paschen, Mendeleev, Hertzsprung, Keepler, Mach, Michelson, Campbell, Mare Moscovense, Compton Birkoff, Pasteur, D. Alembert, Blanchard.

Richardo Brown

The Moon: Satellite of Planet Earth

The Moon is 2,160 miles (3,476 kilometers) in diameter, one quarter the diameter of earth. The moons mass is 1/81 the mass of earth. Its density is 3.3 times the density of water. Hydrogen, helium, neon and argon atoms make up its atmosphere. It’s made of solid rock, rills, and craters and dried up lava mares. There is no liquid water to crode the surface and no active volcanism. The moon crusted and cooled down about 4.6.b.y.a. with its rocks at most 4.5 billion years old, so moon rocks are bone dry. The moon is made of material blasted out of Earth by a huge object up to three tomes the mass of Mars that struck a glancing blow to the young Earth. The Giant Impact (GP) knocked all this material up in onto space as a vapor of hot rock. Like huge stone material snowflakes it condensed and solidified, knocking together in powerful impacts of accumulated rock in big pieces, and then melted by lava from the impacts forming “The Moon” the impact of craters from planetubles, asteroids and comets dating 3.b.y.a.

The Moon: Explore

Richardo Brown: Signature installed and instrumented on the Lunar Reconnaissance Orbiter

Craters dot the moon’s surface. Materials thrown from impacts that made them centers radial patterns of bright ejecta with scars left over by objects that smashed the earth in our early solar system of the star: Sun. The largest are the impact basins, enormous craters ranging up to around (1,553mi) across. Lava flooded the basin floor sometime after titanic collisions formed them, creating the smooth, dark surfaces that the eye geography maps as Marias or Seas. Blocks of rock hurled formed with impacts gathering and becoming larger made what is called the satellite of planet Earth.

Fissures, domed hills and wrinkling ridges all fissioned together with ancient volcanic lava and weak gravity formed geological igneous basalt and metamorphic anothosite. The lunar surface is sheathed in regolith, a fine dusty titkite, cleared by constant bombardment of asteroids, comets, and meteoroids. The geology of the moon was brought back to planet Earth by six crews of Apollo astronauts from 1969 to 1972. The rocks and dust were completely dry discovering the moon has no water of its own. The moon is sometimes bombarded by icy – water tailed comets. Most of the cometary’s water evaporizates into space, but some of it may be trapped as ice in the bottoms of shadowing craters near the lunar polar areas. Until a few years ago today the temperature on the moons at it coldest point was -274 degrees.

The highlands of the moon are packed together indicating that these ancient areas were hit repeatedly by asteroids and comets and planetoids, in the violent days of our solar system.

My naming of a few mares (seas) on the satellite Moon:

Near side to the planet Earth:

Oceanus Procellarum

Mares: Frigorius, Serenitatis, Imbrium, Tranquilitatis, Crisium, Fecunditatis, Humorum, Nubrium, Nectaris, orientale, Cognitum.

Grography on the United States and European Space Agencies landings on the Moon:

Apollo 11 – Tranquility Base, Ranger 8 – Mare Tranquilitatis, Sureyor 5, Ranger 6, Apollo 16 – Mare Serenitatis, Luna 21,

Mare Crisium: Luna 15, Luna 23, Luna 24. Mare Fecunditatis: Luna 26, Luna 18 Luna 20. Mare Imbrium: Luna 17, Luna 2. Mare Imbrium and Palus Putredinus. Sinus Aestuum: Suveyor 8. Senus Medii: Suveyor 6, Suveyor 4. Oceanus Procellarium: Luna 8, Luna 9, Luna 7, Suveyor 1. Mare Cognitum: Luna 5, Apollo 12, Suveyor 3, Ranger 7. Alphonsus (crater) Ranger 9. Hipporchus and Thophilus 6800 (craters) Tycho : Surveyor 7

Far Side in the dark sideof the Moon: Ioffe( crater) Ranger 4. Apollo, Mendel, Lyman, Von Karman, Mare Korolev, Paschen, Mendeleev, Hertzsprung, Keepler, Mach, Michelson, Campbell, Mare Moscovense, Compton Birkoff, Pasteur, D. Alembert, Blanchard.

Richardo Brown

L.R.O. Moon Mission

Planetary Society Millenninum Edition 2000/ Membership Directory 1999

Mars 2013 (Astronomy Textbook 2015c.e.)

Jon Hanford December 15, 2010 at 1:56 PM

ricktheruler,

You forgot Apollos 14, 15 & 17, twice! Add to that Apollos 8, 10 & 13, that flew in close proximity to the moon.

Comments on this entry are closed.

Previous post:

Next post: