APOD: Lisbon Honey Moon (2014 Jun 21)

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APOD: Lisbon Honey Moon (2014 Jun 21)

Post by APOD Robot » Sat Jun 21, 2014 4:10 am

Image Lisbon Honey Moon

Explanation: The Sun set on Friday the 13th as a full Honey Moon rose, captured in this well-planned time-lapse sequence. Lisbon, Portugal's Christ the King monument is in the foreground, about 6 kilometers distant from camera and telephoto lens. During the days surrounding today's solstice (June 21, 10:51 UT) the Sun follows its highest arc through northern hemisphere skies as it travels along the ecliptic plane. At night the ecliptic plane is low, and the Full Moon's path close to the ecliptic was also low, the rising Moon separating more slowly from the distant horizon. Northern moon watchers were likely to experience the mysterious Moon Illusion, the lunar orb appearing impossibly large while near the horizon. But the photo sequence shows the Moon's apparent size did not change at all. Its light was initially scattered by the long line-of-sight through the atmosphere though, and a deeper reddened color gave way to a paler gold as the Full Moon rose into the night.

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by SMesser » Sat Jun 21, 2014 12:29 pm

This seems wrong, or perhaps poorly worded:
During the days surrounding today's solstice (June 21, 10:51 UT) the Sun follows its highest arc through northern hemisphere skies as it travels along the ecliptic plane. At night the ecliptic plane is low, and the Full Moon's path close to the ecliptic was also low
How can the ecliptic plane be high during the day and low at night?

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by neufer » Sat Jun 21, 2014 12:51 pm


SMesser wrote:
This seems wrong, or perhaps poorly worded:
During the days surrounding today's solstice (June 21, 10:51 UT) the Sun follows its highest arc through northern hemisphere skies as it travels along the ecliptic plane. At night the ecliptic plane is low, and the Full Moon's path close to the ecliptic was also low
How can the ecliptic plane be high during the day and low at night?
:arrow: The ecliptic plane is indeed low at night when it is high during the day (and vice versa).
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by neufer » Sat Jun 21, 2014 12:52 pm

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by saturno2 » Sat Jun 21, 2014 12:57 pm

Interesting image

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Chris Peterson » Sat Jun 21, 2014 2:51 pm

SMesser wrote:How can the ecliptic plane be high during the day and low at night?
The orientation of the ecliptic with respect to the horizon changes constantly over the course of a day. Keep in mind that the Sun will always lie on the projection of the ecliptic on the sky at any given time, but the ecliptic at that moment doesn't show where the Sun will be at other times.

For instance, today (a solstice) the ecliptic directly intersects the east and west cardinal points on the horizon at local noon. But we know that the Sun neither rises nor sets at those points today (it only does that at the other quarter points, the equinoxes).
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Cousin Ricky » Sat Jun 21, 2014 3:37 pm

At sunset near the solstice, wouldn't the ecliptic be midway between its highest and lowest positions?

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by neufer » Sat Jun 21, 2014 3:57 pm

Cousin Ricky wrote:
At sunset near the solstice, wouldn't the ecliptic be midway between its highest and lowest positions?
The zenith ecliptic would be midway between its highest and lowest positions.

However, neither the sun nor the full moon is near zenith at sunset.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Chris Peterson » Sat Jun 21, 2014 4:10 pm

neufer wrote:The zenith ecliptic would be midway between its highest and lowest positions.
Actually, it would be midway between its northernmost and southernmost positions, which are not necessarily the highest and lowest. For instance, if you were on the equator the ecliptic intersects the zenith at sunrise and sunset, and therefore is at its highest for the day at those times.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by neufer » Sat Jun 21, 2014 4:45 pm

Chris Peterson wrote:
neufer wrote:
The zenith ecliptic would be midway between its highest and lowest positions.
Actually, it would be midway between its northernmost and southernmost positions, which are not necessarily the highest and lowest. For instance, if you were on the equator the ecliptic intersects the zenith at sunrise and sunset, and therefore is at its highest for the day at those times.
I thought we were in Lisbon.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Rothkko » Sat Jun 21, 2014 5:22 pm

en APOD, no es posible cambiar 2014 June 20 x 2014 June 21?

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Chris Peterson » Sat Jun 21, 2014 6:18 pm

neufer wrote:
Chris Peterson wrote:
neufer wrote:
The zenith ecliptic would be midway between its highest and lowest positions.
Actually, it would be midway between its northernmost and southernmost positions, which are not necessarily the highest and lowest. For instance, if you were on the equator the ecliptic intersects the zenith at sunrise and sunset, and therefore is at its highest for the day at those times.
I thought we were in Lisbon.
Would that be the royal we? I'm not. The answer to the question is location dependent. Even for Lisbon, however, the zenith ecliptic does not lie halfway between its highest and lowest positions on the solstice. Today, in Lisbon, the zenithal ecliptic moves between +75° at noon and +28 degrees at midnight (in both cases, with an azimuth of 180°). At sunrise and sunset, the zenithal ecliptic is at +42°. It's between the two extremes, but not at the midpoint.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Ann » Sat Jun 21, 2014 7:22 pm

This APOD really demonstrates that the light that reaches us from the Moon is reddened when the Moon is near the horizon, and more reddened the closer to the horizon it is.

But it is not only the Moon that becomes reddened near the horizon. The Sun does too. But the Sun, and the Moon, become reddened not only near the horizon, but even when they are high in the sky. Even then their light has to pass through the Earth's atmosphere before it can reach our eyes. Even then their light is reddened.

Everyone knows that the Sun is yellow, right? Wrong. It is just reddened by the atmosphere of the Earth.

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by Chris Peterson » Sat Jun 21, 2014 7:46 pm

Ann wrote:This APOD really demonstrates that the light that reaches us from the Moon is reddened when the Moon is near the horizon, and more reddened the closer to the horizon it is.

But it is not only the Moon that becomes reddened near the horizon. The Sun does too. But the Sun, and the Moon, become reddened not only near the horizon, but even when they are high in the sky. Even then their light has to pass through the Earth's atmosphere before it can reach our eyes. Even then their light is reddened.
And for those of us who make photometric measurements, compensating for this effect is critical. You like to discuss those B-V values a lot. But the atmosphere attenuates the B and V bands differently depending on the zenith distance. It requires a lot of painstaking calibration to get good B-V (or any other photometric color) measurements. It would be a lot easier from space.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by zbvhs » Sat Jun 21, 2014 8:03 pm

It is called an illusion, after all.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by neufer » Sat Jun 21, 2014 9:34 pm

zbvhs wrote:
It is called an illusion, after all.
A Lisbon illusion conclusion :?:
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by OriEri » Sun Jun 22, 2014 1:58 am

How can the ecliptic plane be high during the day and low at night?
Neufer provided a diagram and some others gave curt explanations, but if you are not familiar with thinking about the celestial sphere you still might not understand. Imagine the earth's equator and poles projected into sky. These will be the celestial equator and poles.

If you look at Neufer's diagram of the tilt of the ecliptic relative to the equator, the part of the ecliptic that crosses an imaginary north-south line at your location (also called the local meridian) will have a different position relative to the celestial equator depending where on Earth you are. At the summer solstice, the arrow marked "oribt direction" in Neufers image is actually the direction towards the sun. The sun is on the ecliptic, by definition, so at the summer solistice, when you are on the part of the Earth where the sun is crossing the local meridian, the sun is as high as it gets above the celestial equator (23.5 degrees).

The full moon will be directly opposite the sun ( on the ecliptic +/- about 5 degrees due to the tilt of the moons orbit relative to the earth's and celestial equator) so, when the full Moon crosses your local meridian (midnight) it and the ecliptic are as low as they get below the celestial equator. The net effect of all this is at the summer solistice, when the sun crosses the meridian it will be (90-your local latitude+23.5) degrees above the horizon. So at the north pole it will be 23.5 above the horizon all day. At a temperate latitude, say Baltimore in the US of ~40 degrees, it will be 63.5 degrees above the horizon.

Now, swing around to midnight and the full moon crossing the meridian and height of the moon above the horizon will be (90-local latitude - 23.5) degrees. You will see that at the north pole the moon will be 23.5 degrees below the horizon..it never rises. This makes sense when you think about how the full moon MUST be 180 degrees opposite the sun in the sky...yet the sun never sets that day, so the moon never rises, Just like how the sun will not rise at the north pole during the winter solstice. At our temperate latitude of Baltimore, old moon is 90-40-23.5 ...a scant 16.5 degrees above the horizon at its highest point of the night.

There is a nice diagram here illustrating the sun's motion through the sky at different times of year. Just remember the full moon will be opposite the sun whenever it is full and you will see how it remainins lower on the horizon.

Now for my question: I did not find the defintion of "honey moon" anywhere (admittedly I gave up on google after only 10-15 minutes.) Does this refer to full moons near the solstice? Is it called that because the full moon remains visibly reddened (yellowed?) all night at temperate latitudes because, using Baltimore as our example, it will be peeking through about 3-1/3 thicknesses of atmosphere?

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by geckzilla » Sun Jun 22, 2014 2:11 am

OriEri wrote:Now for my question: I did not find the defintion of "honey moon" anywhere (admittedly I gave up on google after only 10-15 minutes.) Does this refer to full moons near the solstice? Is it called that because the full moon remains visibly reddened (yellowed?) all night at temperate latitudes because, using Baltimore as our example, it will be peeking through about 3-1/3 thicknesses of atmosphere?
Just a romanticized name for the full moon of June... similar to other notions. Harvest moon, etc. You can kind of make up any folklore you want for it. It's just like the constellations in the sky.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by LocalColor » Sun Jun 22, 2014 2:35 am

The Farmer's Almanac called the June full moon the "Strawberry Moon". I think I like Honey Moon better.

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by owlice » Sun Jun 22, 2014 3:51 am

"Honey moon, keep a-shinin' in June," as the song says.
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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by DavidLeodis » Sun Jun 22, 2014 12:21 pm

It's a superb sequence of images of the Moon. :)

It reminds me of sci-fi films where a massive meteor is just about to hit the Earth! :wink:

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by DavidLeodis » Sun Jun 22, 2014 1:22 pm

In the explanation as it currently is it states "...the photo sequence shows the Moon's apparent size did not not change...". I was not going to mention it but I have now decided that I would as the double negative could be used to mean that the apparent size of the Moon did change! I think the text should have stated "...apparent size did not change...". I was not deliberately looking for possible errors as it was just that the double use of "not" seemed obvious when I read the explanation.

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by DavidLeodis » Mon Jun 23, 2014 1:38 pm

DavidLeodis wrote:In the explanation as it currently is it states "...the photo sequence shows the Moon's apparent size did not not change...". I was not going to mention it but I have now decided that I would as the double negative could be used to mean that the apparent size of the Moon did change! I think the text should have stated "...apparent size did not change...". I was not deliberately looking for possible errors as it was just that the double use of "not" seemed obvious when I read the explanation.
Thanks to who did the amending as I've noticed that the extra "not" has now been removed from the explanation to the APOD in this discussion. The explanation to the APOD in the archive still currently however has the extra "not".

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Re: APOD: Lisbon Honey Moon (2014 Jun 21)

Post by geckzilla » Mon Jun 23, 2014 2:37 pm

DavidLeodis wrote:
DavidLeodis wrote:In the explanation as it currently is it states "...the photo sequence shows the Moon's apparent size did not not change...". I was not going to mention it but I have now decided that I would as the double negative could be used to mean that the apparent size of the Moon did change! I think the text should have stated "...apparent size did not change...". I was not deliberately looking for possible errors as it was just that the double use of "not" seemed obvious when I read the explanation.
Thanks to who did the amending as I've noticed that the extra "not" has now been removed from the explanation to the APOD in this discussion. The explanation to the APOD in the archive still currently however has the extra "not".
Just FYI you can email Bob and Jerry and one of them will usually get around to fixing the error.
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