Image: Full moon
Starry Night Software
The full moon of December is called the oak moon. Other names include the frost moon, winter moon and the long night’s moon. In Hindi it is known as margashirsha poornima. Its Sinhala (Buddhist) name is unduvap. The full moon rises around sunset and sets around sunrise, the only night in the month when the moon is in the sky all night long. The rest of the month, the moon spends at least some time in the daytime sky.
updated 12/26/2012 2:25:07 PM ET 2012-12-26T19:25:07

The last full moon of 2012 will rise into the night sky this week in a year-ending lunar treat.

The full moon is actually an instantaneous event when the moon is exactly opposite the sun in the Earth's sky, and this month that occurs on Friday morning, Dec. 28, at 5:21 a.m. EST (1021 GMT). But, to the naked eye, the moon "looks" full for a couple of days on either side of that time, so the exact date doesn't matter.

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Many owners of new telescopes are disappointed when they look at the planets. At its largest, the planet Venus is just barely one arc minute in diameter, about 1/30th of the diameter of the sun or the moon, and all the other planets appear smaller than that.

Telescope owners complain that the planets don't look any larger with a telescope than they do with the naked eye. That isn't true of course, because any telescope will magnify everything dozens or hundreds of times. But when something is as small as a planet, even a lot of magnification won't make it look very big.

[ Amazing Moon Photos of 2012 ]

Moon size comparison
The reason why the sun appears 30 times bigger than Venus is because the sun is very large. Its true diameter is more than 100 times that of Venus, or of Earth, for that matter, since Venus and Earth are about the same size. The moon appears 30 times bigger than Venus not because it is large, but because it is very close to us. The moon is 2,159 miles in diameter (3,475 kilometers), as compared to the Earth's 7,926 miles (12,756 km) and Venus' 7,521 miles (12,104 km).

In other words, the moon is just slightly more than a quarter of the diameter of the Earth or Venus. Mercury is the planet closest in size to the moon at 3,032 miles in diameter (4,879 km), about 40 percent larger than our moon. One of the reasons that Pluto was demoted to "dwarf planet" status was its small diameter of only 1,485 miles (2,390 km), two-thirds of the diameter of our moon.

Our moon is very large in proportion to its planet, Earth, more than any other moons in the solar system except for Pluto's moon Charon. But because other planets are much larger than Earth, several of their moons are much larger than ours, including three of Jupiter's moons (Io, Ganymede, and Callisto) and one of Saturn's (Titan). Of these, Ganymede is the largest at 3,270 miles (5,262 km), slightly larger than the planet Mercury.

The moon as a planet
Even if you don't own a telescope, looking at the moon with the naked eye can show you the challenges faced by planetary observers.

Earlier this week we saw Jupiter shining brightly alongside the moon. It would take a telescope magnifying about 40 times to make Jupiter appear as big as the moon does with the naked eye. When Mars was closest to Earth in 2003, it took a telescope magnifying 75 times to make Mars appear as big as the moon with the naked eye. At present Mars on the far side of the sun, and requires a telescope magnifying 430 times to make it appear as big as the moon does with the naked eye.

So, if you want an observing challenge similar to trying to spot Jupiter's Great Red Spot or Mars' polar cap, try observing detail on the moon with your naked eye.

The man in the moon
What most people see when they look at the moon is " the man in the moon." This is a pattern of light and dark caused by the albedo markings on the moon. “Albedo” is a measure of how much light gets reflected by an area on a planet.

Darker areas on the moon's surface, which the early astronomers called "seas," although we now know that they are dry and airless, form the face of a man, in our mind’s eye. Or, they may form a woman, or a rabbit, depending on your culture. These are very similar to the dusky markings which astronomers observe with telescopes on Mars and Mercury, also called albedo markings.

If you try to sketch the markings you see on the moon, you will find, as experienced planetary observers do, that you can see much finer detail than the man in the moon. You should be able to see some of the smaller seas, such as the Mare Crisium, on the eastern limb of the moon, and one or two of the brighter craters, such as Tycho towards the southern limb.

Once you have tried to sketch the moon with your naked eye, try observing it with a small binocular. You will be amazed at how much more detail you can see, and will begin to experience the wonder Galileo must have felt when he first turned his primitive telescopes on the moon. There really is another world out there.

If you snap an amazing photo of the year's final full moon on Friday and would like to share it with for a potential story or gallery, submit photos and comments, including your name and location to

This article was provided to by Starry Night Education , the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu .

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Photos: Month in Space: January 2014

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  1. Southern stargazing

    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

    The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps. (NASA) Back to slideshow navigation
  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
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