MOONSCAPES

Moon

Telescopic Views of the Moon

With Lunar Lore and Data

From Jim Kaler

See the animation of the lunar phases.

Visit MOON LIGHT for scenic views of the Moon.

Return to Skylights or STARS

Go to Images of the Moon.

Go to Names of the Full Moons.

Go to Meanings and Locations of Maria.

Go to The Lunar Orbit.

Go to coming Eclipses.

Go to Physical Properties of the Moon.

IMAGES OF THE MOON

Push the Moon-symbol below the picture for labels.

Telescopic views of the Moon are arranged by phase, by age in days since the last new Moon. Click on the Moon-symbol below each image for a labelled version. Maria, volcanically coated impact basins, are generally in blue, impact craters in yellow, mountain ranges (basin rims) in black or white, all depending on contrast. East-west directions are as seen from Earth with north usually to the top.

NAMES OF THE FULL MOONS*

The phases of the Moon have been profoundly important to humankind as a way of keeping track of the flow of time, the interval between same phases (new-to-new, full-to-full) the origin of the month. The months of the Jewish and Islamic calendars are strictly tied to the phase interval (new-to-new). Because 12 lunar months amount to 354.3 days (as opposed to the 365.24 day orbital period of the Earth), the civil calendar, derived from the ancient Roman solar calendar, stretches them out to fit the year.

*Compiled by Randolph E. Schmid of the Associated Press.

MEANINGS AND LOCATIONS OF LUNAR MARIA

See a simple maria map.

The lunar maria (singular mare), Latin for seas, are dark, lava-coated impact basins (in a sense gigantic craters) and other regions that have been volcanically flooded. Roughly three billion years old, they are for the most part all on the Moon's near side, that facing the Earth. Roughly three of more billin years old, they are by far less-heavily cratered, showing that the rate of meteoric impact (the cause of the craters) was dramatically higher before the maria were formed.
LATIN NAME MEANING LOCATION*
Mare Australe Southern Sea Southwest limb
Mare Crisium Sea of Crises West
Mare Foecunditatis Sea of Fecundity West
Mare Frigoris Sea of Cold North
Mare Humboldtianum Humboldt's Sea Northeast limb
Mare Humorum Sea of Humors Southeast
Mare Imbrium Sea of Showers North
Mare Nectoris Sea of Nectar Southwest
Mare Nubium Sea of Clouds East central
Mare Serenitatis Sea of Serenity North central
Mare Smythii Smythe's Sea West limb
Mare Spumans Foaming Sea W. Mare Foecunditatis
Mare Tranquillitatis Sea of Tranquility West central
Mare Vaporum Sea of Vapors Central
Oceanus Procellarum Ocean of Storms East
Lacus Mortis Lake of Death W. Mare Frigoris
Lacus Somniorum Lake of Dreams S. Mare Serenitatis
Palus Nebularum Marsh of Clouds W. Mare Imbrium
Palus Putredinis Marsh of Decay W. Mare Imbrium
Palus Somnii Marsh of Dream NW Mare Tranquillitatis
Sinus Iridum Bay of Rainbows NE Mare Imbrium
Sinus Aestuum Seething Bay E Mare Vaporum
Sinus Medii Central Bay Central
Sinus Roris Bay of Dew E. Mare Frigoris

*As seen from Earth. To an observer on the Moon, east and west are reversed.

THE LUNAR ORBIT*

#The Moon crosses the ecliptic at the nodes, ascending going north, descending going south.

ECLIPSES**

OF THE SUN...

DATE KIND WHERE
April 29, 2014 Annular Australia, Pacific Ocean
October 23, 2014 Partial North America, Eastern Siberia

...AND OF THE MOON

DATE KIND WHERE SPECIAL
April 29, 2014 Total Americas, Pacific South of central shadow
October 23, 2014 Total Americas, Pacific, Asia North of central shadow

For more information, go to

The Moon is eclipsed when it passes through the shadow of the Earth, which can take place only at full Moon (when the Moon is opposite the Sun in the sky). Since the angular size of the Earth's shadow at the distance of the Moon is 1.5 degrees, while the tilt of the lunar orbit relative to the ecliptic is just over 5 degrees, the full Moon usually passes completely above or below the shadow. Lunar eclipses can then take place only when the full Moon is close to the ecliptic, within about 12 degrees of one of the two nodes (the points where the lunar orbit crosses the ecliptic). The two requirements intersect about twice a year. Half the eclipses will take place during daylight with the Moon out of sight, so we might expect to see perhaps one per year.

All shadows have two parts, a dark central umbra that is surrounded by a lighter penumbra in which some light falls. When the Moon is in the penumbra of the Earth's shadow, someone on the Moon would see the Earth cutting off just part of the Sun. Penumbral eclipses, or the penumbral phase of an eclipse, are only barely detectable. In a total eclipse the Moon becomes completely immersed in the Earth's umbral shadow. Totality must be preceded by a partial phase in which only part of the Moon is so immersed. Eclipses can also be partial-only as well, with no total phase (and can also be penumbral-only). During totality, the Moon remains visible from light scattered and refracted into the umbra by the Earth's atmosphere, its brightness depending mostly on the amount of recent terrestrial volcanic activity that can make the air more opaque. The circularity of the Earth's shadow was ancient evidence that the Earth is a sphere. With the Moon moving at roughly its own angular diameter per hour, in a central eclipse totality can last up to 1.5 hours. If we include the partial phases, the total duration maximizes at 3.5 hours.

Eclipses of the Sun can take place only at new Moon, when the Moon passes between us and the Sun. Again, because of the orbital tilt, the Moon usually misses the Sun, going too far north or south. A solar eclipse thus requires not just new Moon but that the Moon also be within about 18 degrees of a node, which must happen at least twice a year. The Moon's full shadow, however, is only a quarter the length of the Earth's, and is just barely long enough to reach us. Only if the Moon is near perigee (its closest point to Earth) can the umbral shadow actually touch the ground, and even then the shadow spot is small (that is, the angular diameter of the Moon is then just slightly greater than that of the Sun). As the Moon orbits and the Earth turns, the umbral shadow spot, no more than 270 kilometers across, sweeps across the Earth, allowing only a handful of people to see a total eclipse, in which all of the Sun is covered by the Moon. The longest duration of any fixed point within the umbral spot is just seven minutes. Only during a total eclipse can we see the surrounding solar corona.

If the Moon, however, is nearer apogee, the zone of total shadow stops short, and the umbra does not reach us (that is, the Moon's angular diameter is not quite as large as the Sun's). We then see an annular eclipse (the path of annularity also sweeping in a tiny path across Earth) in which a ring of sunlight remains around the darkened Moon. Surrounding the umbral spot (or the spot of annularity) will be a continent-sized area in which the solar eclipse is partial, wherein the Moon cuts across only part of the solar disk. Solar eclipses can be partial-only as well. They are about equally divided among total, annular, and just-partial.

CAUTION!. While lunar eclipses are perfectly safe to watch, not so the solar version. Any portion of the visible Sun outside of totality is far too bright to look at and can damage the eye. This caution applies to annular eclipses as well. What is dangerous is not the eclipse itself, but the temptation to look at it without proper protection. Use either a professionally made filter (do NOT try to make one yourself!) or use pinhole projection. Put a tiny hole in a piece of cardboard and project the image onto the ground or a wall. (Do NOT look through the hole!). Spaces between tree leaves act as pinhole cameras, allowing you to watch multiple images of the eclipse in the shade.

The lunar orbit precesses (wobbles) with a period of 18.6 years, which causes the nodes to "regress" to the west over the same interval. The Sun then encounters a given node every 346 days (the eclipse year). As a result of the regression and the general geometry of eclipses, there can be many as three lunar eclipses per year and as many as five solar. There may also be no eclipses of the Moon at all, while there have to be at least two of the solar variety. A total of seven is possible, five solar plus two lunar (which last took place in 1935 and will not happen again until 2160) or four solar plus three lunar (the last in 1982, the next set to be seen in 2094).

PHYSICAL PROPERTIES OF THE MOON***

SOURCES

Aeronautical Chart and Information Service, US Air Force
*The Ever-Changing Sky, J. B. Kaler, Cambridge University Press, Cambridge, 1996
New Atlas of the Moon, T. Legault and S. Brunier, Firefly Books, English Translation of La Grand Atlas de la Lune, 2006.
New Handbook of the Heavens, H. J. Bernhard, D. A. Bennett, and H. S. Rice, McGraw-Hill, New York, 1948.
**The Astronomical Almanac, US Naval Observatory and UK Hydrographic Office, US Government Printing Office, Washington, DC.
***The New Solar System, 4th ed., J. K. Beatty, C. C. Petersen, A. S. Chaiken eds., Sky Publishing Corp (Cambridge MA), Cambridge University Press (Cambridge UK), 1999.

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