APOD: Mercury and Crescent Moon Set (2016 Apr 15)

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APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by APOD Robot » Fri Apr 15, 2016 4:05 am

Image Mercury and Crescent Moon Set

Explanation: Innermost planet Mercury and a thin crescent Moon are never found far from the Sun in planet Earth's skies. Taken near dusk on April 8, this colorful evening skyscape shows them both setting toward the western horizon just after the Sun. The broad Tagus River and city lights of Lisbon, Portugal run through the foreground under the serene twilight sky. Near perigee or closest approach to Earth, the Moon's bright, slender crescent represents about 3 percent of the lunar disk in sunlight. Of course as seen from the Moon, a nearly full Earth would light up the lunar night, and that strong perigee earthshine makes the rest of the lunar disk visible in this scene. Bright Mercury stays well above the western horizon at sunset for northern skywatchers in the coming days. The fleeting planet reaches maximum elongation, or angular distance from the Sun, on April 18. But Mercury will swing back toward the Sun and actually cross the solar disk on May 9, the first transit of Mercury since November 8, 2006.

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Joe Stieber » Fri Apr 15, 2016 7:07 am

I took some pictures of the Crescent Moon and Mercury on the evening of same date, 08-April-2016, except I'm in New Jersey (near Philadelphia, PA) on the east coast of the United States, so I was capturing them about five (5) hours later than today's APOD taken from Lisbon, Portugal. The relatively rapid motion of the moon is well known, roughly its own half-degree diameter eastward every hour, so the moon is noticeably higher with respect to Mercury in my considerably-less-dramatic picture compared to this nice APOD. Of course Mercury, the Winged Messenger, also moved a little eastward during those five hours, about a third of a degree, but the net result was a higher moon for me.

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by heehaw » Fri Apr 15, 2016 11:48 am

I always like looking at Mercury (in real life) when I can. Does anyone think that human beings will ever set foot on Mercury?

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Asterhole » Fri Apr 15, 2016 11:49 am

Joe Stieber wrote:I took some pictures of the Crescent Moon and Mercury on the evening of same date, 08-April-2016, except I'm in New Jersey (near Philadelphia, PA) on the east coast of the United States, so I was capturing them about five (5) hours later than today's APOD taken from Lisbon, Portugal. The relatively rapid motion of the moon is well known, roughly its own half-degree diameter eastward every hour, so the moon is noticeably higher with respect to Mercury in my considerably-less-dramatic picture compared to this nice APOD. Of course Mercury, the Winged Messenger, also moved a little eastward during those five hours, about a third of a degree, but the net result was a higher moon for me.
Oh, I think your photo is rather fine in a bucolic kind of way. I don't believe I have actually ever seen the planet Mercury in Terrestrial skies, being that I live in a rather light-polluted suburb of a major U. S. city.
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Boomer12k » Fri Apr 15, 2016 2:07 pm

Joe Stieber wrote:I took some pictures of the Crescent Moon and Mercury on the evening of same date, 08-April-2016, except I'm in New Jersey (near Philadelphia, PA) on the east coast of the United States, so I was capturing them about five (5) hours later than today's APOD taken from Lisbon, Portugal. The relatively rapid motion of the moon is well known, roughly its own half-degree diameter eastward every hour, so the moon is noticeably higher with respect to Mercury in my considerably-less-dramatic picture compared to this nice APOD. Of course Mercury, the Winged Messenger, also moved a little eastward during those five hours, about a third of a degree, but the net result was a higher moon for me.

I like it... nice shot.

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Boomer12k » Fri Apr 15, 2016 2:14 pm

Until I read the description, I thought it was San Francisco... they have the Golden Gate Bridge and everything... thought it was shot from the Oakland side or something.... Guess not...

I can no longer really get a shot of Mercury as the trees around here are up too high...

Other than that... Here is my shot... back in 2012. Early morning, and actually a bit daylight, but dark in photo. Shot just above the treeline at the time.
merc-1.jpg
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Chris Peterson » Fri Apr 15, 2016 2:48 pm

heehaw wrote:I always like looking at Mercury (in real life) when I can. Does anyone think that human beings will ever set foot on Mercury?
Well, as with the other planets in the Solar System, there's no reason for humans to set foot there. So it's unlikely unless for political purposes (like with current Mars missions under design), or for some future explorer ("because it's there"). Mercury is a very difficult place to get to.
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Fred the Cat » Fri Apr 15, 2016 3:45 pm

Chris Peterson wrote:
heehaw wrote:I always like looking at Mercury (in real life) when I can. Does anyone think that human beings will ever set foot on Mercury?
Well, as with the other planets in the Solar System, there's no reason for humans to set foot there. So it's unlikely unless for political purposes (like with current Mars missions under design), or for some future explorer ("because it's there"). Mercury is a very difficult place to get to.
The setting has been imagined by many over the years.

"A nice place to visit, but I wouldn't want to live there" is unrelated but apropos. :ssmile:
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Chris Peterson » Fri Apr 15, 2016 3:55 pm

Fred the Cat wrote:
Chris Peterson wrote:
heehaw wrote:I always like looking at Mercury (in real life) when I can. Does anyone think that human beings will ever set foot on Mercury?
Well, as with the other planets in the Solar System, there's no reason for humans to set foot there. So it's unlikely unless for political purposes (like with current Mars missions under design), or for some future explorer ("because it's there"). Mercury is a very difficult place to get to.
The setting has been imagined by many over the years.
I enjoyed Kim Stanley Robinson's stories (especially 2312) where a city on Mercury traveled on tracks to stay right on the terminator, always dawn. Of course, in that universe spaceflight was reduced to the routine, and people lived on every body in the Solar System, regardless of how hostile. Good science fiction, but not likely, IMO.
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by gmPhil » Fri Apr 15, 2016 4:23 pm

So what's the inset at bottom-left meant to be?

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Joe Stieber » Fri Apr 15, 2016 4:35 pm

Asterhole wrote:
Joe Stieber wrote:I took some pictures of the Crescent Moon and Mercury on the evening of same date...
Oh, I think your photo is rather fine in a bucolic kind of way. I don't believe I have actually ever seen the planet Mercury in Terrestrial skies, being that I live in a rather light-polluted suburb of a major U. S. city.
Thanks, but the main point of linking my picture was to show the relative movement of the moon during the nominal five-hour span between it and the APOD.

Anyway, a suburban location should not be a hindrance to spotting Mercury. I live just 8 miles from center-city Philadelphia, and I spot Mercury on a regular basis, most often not too far from home. I have a few nearby places that I usually go to, but that's so I have a suitably low horizon. Since Mercury is almost always seen during some stage of twilight, and it can be a fairly bright object, urban and suburban light pollution isn't really a factor as it would be if you were looking for dim "deep sky" objects outside of twilight.

This week, I saw Mercury with unaided eyes on Tuesday evening (April 12th) from a major suburban mall parking lot, and last night (April 14th), from a medical center parking lot. Neither of these locations was particular dark, but Mercury was still easy to see in mid-twilight, but you do need to know where to look. Note that both today's APOD and my picture were taken near large cities (Lisbon and Philadelphia respectively).

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Chris Peterson » Fri Apr 15, 2016 4:41 pm

Asterhole wrote:I don't believe I have actually ever seen the planet Mercury in Terrestrial skies, being that I live in a rather light-polluted suburb of a major U. S. city.
Light pollution is a non-issue, since we only ever see Mercury in bright twilight. But air pollution can be a problem, creating too much scatter in the twilit sky to see the planet. Binoculars help a lot.
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Fred the Cat » Fri Apr 15, 2016 5:06 pm

Chris Peterson wrote:
Fred the Cat wrote:
Chris Peterson wrote: Well, as with the other planets in the Solar System, there's no reason for humans to set foot there. So it's unlikely unless for political purposes (like with current Mars missions under design), or for some future explorer ("because it's there"). Mercury is a very difficult place to get to.
The setting has been imagined by many over the years.
I enjoyed Kim Stanley Robinson's stories (especially 2312) where a city on Mercury traveled on tracks to stay right on the terminator, always dawn. Of course, in that universe spaceflight was reduced to the routine, and people lived on every body in the Solar System, regardless of how hostile. Good science fiction, but not likely, IMO.
Living on a terminator might be possible but it would be hard place to get decent tan. 8-)
Decent tan.jpg
I've read many of Robinson's other books so thanks for the tip on 2312. :thumb_up:
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by rstevenson » Fri Apr 15, 2016 7:44 pm

Chris Peterson wrote:I enjoyed Kim Stanley Robinson's stories (especially 2312) where a city on Mercury traveled on tracks to stay right on the terminator, always dawn. Of course, in that universe spaceflight was reduced to the routine, and people lived on every body in the Solar System, regardless of how hostile. Good science fiction, but not likely, IMO.
A fascinating story with some pretty unlikely future living arrangements, both physical and social. One event in the story (I won't give it away here) nicely illustrated the key weakness of a moving city.
Fred the Cat wrote:Living on a terminator might be possible but it would be hard place to get decent tan.
Actually, it'd be quite easy, and quite fast too. You just decide how much tan you want, on a scale of none to smokin', pick a spot on a hill top with a handy rock to duck behind, disrobe and spin at an appropriate speed. A helper or two and a good medical plan would be useful.

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Chris Peterson » Fri Apr 15, 2016 8:04 pm

rstevenson wrote:
Fred the Cat wrote:Living on a terminator might be possible but it would be hard place to get decent tan.
Actually, it'd be quite easy, and quite fast too. You just decide how much tan you want, on a scale of none to smokin', pick a spot on a hill top with a handy rock to duck behind, disrobe and spin at an appropriate speed. A helper or two and a good medical plan would be useful.
Don't forget that spinning part, though.
o-BILL-MCELLIGOTT-SUN-DAMAGE-570.jpg
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Tekija » Fri Apr 15, 2016 8:13 pm

Joe Stieber wrote:I took some pictures of the Crescent Moon and Mercury on the evening of same date, 08-April-2016, except I'm in New Jersey (near Philadelphia, PA) on the east coast of the United States, so I was capturing them about five (5) hours later than today's APOD taken from Lisbon, Portugal. The relatively rapid motion of the moon is well known, roughly its own half-degree diameter eastward every hour, so the moon is noticeably higher with respect to Mercury in my considerably-less-dramatic picture compared to this nice APOD. Of course Mercury, the Winged Messenger, also moved a little eastward during those five hours, about a third of a degree, but the net result was a higher moon for me.
Still a very nice image, this one too.

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Tekija » Fri Apr 15, 2016 8:36 pm

Chris Peterson wrote:
rstevenson wrote:
Fred the Cat wrote:Living on a terminator might be possible but it would be hard place to get decent tan.
Actually, it'd be quite easy, and quite fast too. You just decide how much tan you want, on a scale of none to smokin', pick a spot on a hill top with a handy rock to duck behind, disrobe and spin at an appropriate speed. A helper or two and a good medical plan would be useful.
Don't forget that spinning part, though.]
Actually, even on planet Earth it looks something like this, spin or not:

http://www.cnet.com/news/uv-photography ... ed-selves/

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by geckzilla » Sat Apr 16, 2016 2:04 am

Tekija wrote:Actually, even on planet Earth it looks something like this, spin or not:

http://www.cnet.com/news/uv-photography ... ed-selves/
I question whether the spots revealed by UV photography are actually skin damage. People are apt to say that because oh, look how flawed and awful it looks, but the presence of melanin doesn't necessarily mean damaged. And the effects of age also don't necessarily mean damaged. This is similar to the way people think of bacteria as dirty invaders who don't belong in or on a body and that we need to purify them away. The individual without the protective melanin would be more susceptible to damage. Indeed, someone with "perfect" white skin under UV light I would guess is extremely susceptible to cancer.
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Tekija » Sat Apr 16, 2016 5:00 am

geckzilla wrote:
Tekija wrote:Actually, even on planet Earth it looks something like this, spin or not:

http://www.cnet.com/news/uv-photography ... ed-selves/
I question whether the spots revealed by UV photography are actually skin damage. People are apt to say that because oh, look how flawed and awful it looks, but the presence of melanin doesn't necessarily mean damaged. And the effects of age also don't necessarily mean damaged. This is similar to the way people think of bacteria as dirty invaders who don't belong in or on a body and that we need to purify them away. The individual without the protective melanin would be more susceptible to damage. Indeed, someone with "perfect" white skin under UV light I would guess is extremely susceptible to cancer.
But it is not melanin that the images highlight. It is structural damage to the skin. For example, the connective tissue files are subject to actinic damage, easily seen histopathologically in skin biopsies. Melanin is good and protective. This is why sunshine increases it, it is a defence response. However, not foolproof. Get too much ultraviolet and the ultraviolet radiation eventually damages the DNA in a way initiating a multistep sequence leasing to melanoma. Similarly, the other skin cells take damage and may develop basal cell and squamous carcinomas.

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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by geckzilla » Sat Apr 16, 2016 7:21 am

Tekija wrote:But it is not melanin that the images highlight. It is structural damage to the skin. For example, the connective tissue files are subject to actinic damage, easily seen histopathologically in skin biopsies. Melanin is good and protective. This is why sunshine increases it, it is a defence response. However, not foolproof. Get too much ultraviolet and the ultraviolet radiation eventually damages the DNA in a way initiating a multistep sequence leasing to melanoma. Similarly, the other skin cells take damage and may develop basal cell and squamous carcinomas.
Are you a dermatologist or otherwise have some expertise in this? I'm curious to know because I've been having a hard time finding information on it, myself. Based on the nature of melanin and how it absorbs and dissipates UV light, I find it very hard to believe that those dark, absorptive areas in the UV imagery could not involve melanin somehow. The whole "skin damage" thing strikes me as a gimmick and a scare tactic to try to trick people into thinking they can somehow stop these otherwise invisible spots from appearing in visible light later in life.
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Re: APOD: Mercury and Crescent Moon Set (2016 Apr 15)

Post by Virbap » Sat Apr 16, 2016 10:31 am

The city lights are not those of Lisbon. The photo in itself was taken from the right side of the estuary, north of the river, on the actual side of the city of Lisbon. The statue of the Christ and city lights are found in the city of Almada, south of the river.