MELK (APOD 2009 April 17)

[Chris Peterson]

The moon is not treated explicitly
(except for the "unusual" fact that it shines by reflected light from the sun)
because ALL planets are on epicycles.

I understand that (and I also think the Wikipedia article needs a little bit of cleaning up). But I still don't know if the Moon was treated somewhat differently, since it clearly behaves differently. That is, it doesn't show apparent retrograde and prograde motion against the sky, and to the degree that irregularities in position could have been detected, they wouldn't correspond to the same epicycle that would produce the difference in distance. So my questions remain: were epicycles used to explain the varying distance to the Moon, and what sort of special exceptions (if any) were used in dealing with the Moon? This manuscript clearly doesn't show a lunar epicycle.

[neufer]

Getting back to beer (or was that another thread)

The Ariadne thread? (I really haven't a clew.)

Bacchus and Ariadne (1520-23) is an oil painting by Titian. An advance payment was given to Raphael, who originally held the commission for the subject of a Triumph of Bacchus. At the time of Raphael's death in 1520, only a preliminary drawing was completed and the commission was then handed to Titian. The painting, considered one of Titian's greatest works, now hangs in the National Gallery in London. Ariadne has been left on the island of Naxos, deserted by her lover Theseus, whose ship sails away to the far left. She is discovered on the shore by the god Bacchus, leading a procession of revelers in a chariot drawn by two cheetahs. Bacchus is depicted in mid-air as he leaps out of the chariot to protect Ariadne from these beasts. In the sky above the figure of Ariadne is her crown, which Bacchus has thrown into the sky and it then becomes the constellation Corona.

[neufer]

The moon is not treated explicitly
(except for the "unusual" fact that it shines by reflected light from the sun)
because ALL planets are on epicycles.

I understand that (and I also think the Wikipedia article needs a little bit of cleaning up). But I still don't know if the Moon was treated somewhat differently, since it clearly behaves differently. That is, it doesn't show apparent retrograde and prograde motion against the sky, and to the degree that irregularities in position could have been detected, they wouldn't correspond to the same epicycle that would produce the difference in distance. So my questions remain: were epicycles used to explain the varying distance to the Moon, and what sort of special exceptions (if any) were used in dealing with the Moon? This manuscript clearly doesn't show a lunar epicycle.

The lunar clockwise epicycle would have the same period (i.e., 27.5 days) as it's counterclockwise orbital cycle. Hence the full orbit appears to be, essentially, an off axis circle. Apollonius was apparently at least as aware of lunar "irregularities in position" as of the varying lunar distance.

<<The hypothesis of eccentric orbits, or equivalently, deferent and epicycles, to explain the apparent motion of the planets and the varying speed of the Moon, are also attributed to [Apollonius of Perga (ca. 262 BC–ca. 190 BC)].>>

[Frenchy]

Double lunar orbits...a blue moon perhaps?

[aristarchusinexile]

Speaking of celestial shapes .. the flattening of the poles of the sun is suggested as a means of accounting for Merury's perihelion .. and as Mercury was the 'cornerstone' for the acceptance and promotion of Relavity, the flattening throws Relativity into doubt, again. Moffat's book 'Reinventing Gravity' should be a must read for anyone truly interested in astronomy. By the way, Moffat honours Einstein throughout the book, just as Einstein honoured Newton.


Come on Chris, I expected you to rise to the occasion ( and I don't mean that harshly .. but in the spirit of Comraderie .. passing the vodka, etc. )

[aristarchusinexile]

Double lunar orbits...a blue moon perhaps?

Frenchy, spend a winter or two in northern Ontario or Quebec, Canada, perhaps in the prairie provinces as well, and you are almost guaranteed seeing a true Blue Moon, in which the colour of the moon is truly blue.

[BMAONE23]

Double lunar orbits...a blue moon perhaps?

Frenchy, spend a winter or two in northern Ontario or Quebec, Canada, perhaps in the prairie provinces as well, and you are almost guaranteed seeing a true Blue Moon, in which the colour of the moon is truly blue.

Is it that the moon appears blue or is it that the viewpoint is through frozen eyeballs???

[aristarchusinexile]

Is it that the moon appears blue or is it that the viewpoint is through frozen eyeballs???

I can't imagine winking with frozen eyeballs, but the first cold spell of summer here, when I get the dog sled out, I'll try.

For the casual observer here, the moon truly appears to be coloured blue .. an action of diffraction, not a wackson of a Jackson or a cantaloupe. The shadow of the cantaloupe set out during a blue moon is also blue if the shadow falls on white snow, as all shadows are blue in that time and place. A truly striking scene, one which should be witnessed by every so-called highly educated person who falls victim to the brainwashing and programming of their organic computer which dictates to them that blue moons are not blue, but are merely every second full moon of a month. Sheesh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! and Double Sheesh!! Triple Sheesh even!!! And then some. 8)

[BMAONE23]

Is it that the moon appears blue or is it that the viewpoint is through frozen eyeballs???

I can't imagine winking with frozen eyeballs, but the first cold spell of summer here, when I get the dog sled out, I'll try.

For the casual observer here, the moon truly appears to be coloured blue .. an action of diffraction, not a wackson of a Jackson or a cantaloupe. The shadow of the cantaloupe set out during a blue moon is also blue if the shadow falls on white snow, as all shadows are blue in that time and place. A truly striking scene, one which should be witnessed by every so-called highly educated person who falls victim to the brainwashing and programming of their organic computer which dictates to them that blue moons are not blue, but are merely every second full moon of a month. Sheesh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! and Double Sheesh!! Triple Sheesh even!!! And then some. 8)

Count me in for a visit there and soon

[Frenchy]

Does this mean that the "blue moon" is the brown moon in the photograph that I have, because I thought the blue one would have been the blue moon?

Probably a dumb question, but could the Earth/moon system be considered a double planet?

To Aristarchusinexile...it has been a few years since I was last in the Canadian prarie provinces. Could I see a true blue moon if I went to Maine in the wintertime?

[Dr. Skeptic]

A Blue Moon is simply the second full moon of a calendar month - nothing to do with it's color. A Blue Moon will occur in any year when the first full moon falls on or before January 11th.

[bystander]

A Blue Moon is simply the second full moon of a calendar month - nothing to do with it's color.

Actually, that is a mistake, an error in interpretation made in 1946.

A blue moon is a full moon that is not timed to the regular monthly pattern. Most years have twelve full moons which occur approximately monthly, but in addition to those twelve full lunar cycles each calendar year contains an excess of roughly eleven days. The extra days accumulate, so that every two or three years (on average about every 2.7154 years) there is an extra full moon. The extra moon is called a "blue moon." Different definitions place the "extra" moon at different times.

• In calculating the dates for Lent and Easter, the Clergy identify the Lent Moon. It is thought that historically when the moon's timing was too early they named an earlier moon as a "betrayer moon" ("belewe" moon), thus the Lent moon came at its expected time.
  
  Folklore gave each moon a name according to its time of year. A moon which came too early had no folk name - and was called a blue moon - bringing the correct seasonal timings for future moons
  
  The Farmer's Almanac defined blue moon as an extra full moon that occurred in a season; one season was normally three full moons. If a season had four full moons, then the third full moon was named a blue moon.
  
  Recent popular usage defined a blue moon as the second full moon in a month, stemming from an interpretation error made in 1946 that was discovered in 1999.

The term "blue moon" is commonly used metaphorically to describe the rarity of an event, as in the saying "once in a blue moon."

What's a Blue Moon?
Sky and Telescope - May 1999

• The trendy definition of "Blue Moon" as the second full Moon in a month is a mistake.

[neufer]

Early English and Christian usage

The earliest recorded English usage of the term "blue moon" was in 1528 in a pamphlet
violently attacking the English clergy, entitled Rede Me and Be Not Wrothe [Read me and be not angry]:

• "Yf they say the mone is belewe / We must believe that it is true"
  [If they say the moon is blue, we must believe that it is true].

Some interpret this "blue moon" as relating to absurdities and impossibilities,
and a similar moon-related adage was first recorded in the following year:

• "They would make men beleue ... that þe Moone is made of grene chese"
  [They would make men believe ... that the moon is made of green cheese].

An alternative interpretation uses the other old English meaning of "belewe" (which can mean "blue" or "betrayer"). The church was responsible for the calendar and used the complex computus to calculate the important date of Easter, which is based on the full moon. Lent falls before Easter starting at the beginning of the Lent moon cycle (late winter moon). The next moon is the egg moon (early spring moon), and Easter usually falls on the first Sunday after the full egg moon. Every one to three years the Lent and egg moons would come too early, so the clergy would have to tell people whether the moon was the Lent moon or a false one, which they may have called a "betrayer moon".
........................................
Visibly blue moon

The most literal meaning of blue moon is when the moon (not necessarily a full moon) appears to a casual observer to be unusually bluish, which is a rare event. The effect can be caused by smoke or dust particles in the atmosphere, as has happened after forest fires in Sweden and Canada in 1950 and, notably, after the eruption of Krakatoa in 1883, which caused the moon to appear blue for nearly two years.
........................................
Folklore

Historically, moons were given folk names, twelve each year, to help people to prepare for different times of the year and the related weather and crop needs. Names varied with locality and culture, often with descriptive names such as harvest moon, growing moon, snow moon, and egg moon. Most years have 12 moons (given 12 names) - but in the years with thirteen full moons the monthly "seasons" would be expected to come too early - hens would not recommence laying their eggs when expected after winter as it was still too cold - so the early moon was named a "blue moon", which then re-aligned the rest of the year's moons and 'seasons'.