BajaNomad - the moon in Baja

I always thought it was from how the earth lined up between the sun and the moon blocking sunlight to the moon.

like during an eclipse? I guess I never really thought about it..... :light:

4x4abc - 5-8-2016 at 11:55 AM

I always thought it was from how the earth lined up between the sun and the moon blocking sunlight to the moon.

that's called an eclipse - doesn't happen often

4x4abc - 5-8-2016 at 12:09 PM

Quote: Originally posted by Bwana_John

synchronous rotation, and our relatively fixed viewing location

Quote:

I ask why on most days we see only part of the moon

You can see ALL of it on some days (without leaving earth)???

I should have been more careful with my words.

Why do we see only part of the moon illuminated by the sun most days?
Like in the image above, we also see the part that is illuminated by earth.
And like any other object in the universe, we never see more than 1/2.

And no, no Wikipedia or Google involved. Just many many years around campfires in Baja. Disclaimer: Some Pacifico and Tequila involved. I figured it out myself.

Wikipedia and Google search don't really give you a simple to understand answer. Most diagrams are even wrong.
But who cares. With TV you rarely ever see the moon.

4x4abc - 5-8-2016 at 12:22 PM

Quote: Originally posted by Russ

WOW ! That is a spectacular photo!

Thank you!
No rocket science. Camera, 200mm lens, tripod - shoot.
The star burst effect around Venus comes from the number of shutter blades in the lens and the aperture setting (11 or higher)
took about 50 shots or so to get it right

woody with a view - 5-8-2016 at 12:35 PM

Great picture! Here's my alignment from last Nov on the surf side.

4x4abc - 5-8-2016 at 01:29 PM

for all you guys interested about what's in the sky, Stellarium is a free app showing you everything you ever wanted to see (including moving satellites)
http://www.stellarium.org/

woody with a view - 5-8-2016 at 01:38 PM

good program! i've had it on the laptop for years.

bezzell - 5-8-2016 at 02:55 PM

I always thought it was from how the earth lined up between the sun and the moon blocking sunlight to the moon.

wow

4x4abc - 5-8-2016 at 04:32 PM

Quote: Originally posted by bezzell

I always thought it was from how the earth lined up between the sun and the moon blocking sunlight to the moon.

wow

hat's how 99% of the people respond

SFandH - 5-8-2016 at 04:37 PM

I ask why on most days we see only part of the moon

Who looks at the moon during the day?

4x4abc - 5-8-2016 at 05:04 PM

Quote: Originally posted by SFandH

I ask why on most days we see only part of the moon

Who looks at the moon during the day?

with the exception of a few days a month the moon is visible during the day - I look at it when I catch it.
Good example in this thread: http://forums.bajanomad.com/viewthread.php?tid=83023 (image with the Cardon fruits)

bezzell - 5-8-2016 at 07:19 PM

hat's how 99% of the people respond

nonsense
(maybe 99% off-roaders

)

bajabuddha - 5-8-2016 at 07:52 PM

Quote: Originally posted by bezzell

hat's how 99% of the people respond

nonsense
(maybe 99% off-roaders

)

Oh, Bezzellzebub is just teasing with all of you; his superior vegetable-fueled intelligence KNOWS the moon travels in an elliptical orbit around the earth, actually bypassing the earth's shadow (except during lunar and solar eclipses, see later....) and the moon doesn't rotate on its' own axis, but as it travels around us displays only ONE SIDE to the sun.... WOW... he said...

So, as the moon comes from in front of us we see the first quarter and half, and as it travels behind us we see a full moon; the course of the moon is elliptical with an apogee and a perigee, which makes it closer and farther away also, which makes the moon bigger and smaller... but I digress. Moon behind us, FULL MOON. Moon in front of us, NEW MOON (no moon, between sun and us) not only no light on moon, but IT'S FREAKING DAYLIGHT, and you'd need optics to see the moon, but it's right there all the time.

NOW: When that elliptical orbit lines up once in a while (those gall-darned scientists can predict it to the second for hunnerts of thousanth's of days behind and in frunt of us, the bastids) and the sun, moon and earth just HAPPEN to hit a shadow line, BINGO! - - - Eclipse. Or partial. A lotta virgins went down during those, prolly like Bezzelzebub. Maybe a few 4x4'ers too, but I doubt many carnivors; we're still here.

Any logical questions?

[Edited on 5-9-2016 by bajabuddha]

willardguy - 5-8-2016 at 08:05 PM

:lol:

bajaoldmads juiced up on google!

bajabuddha - 5-8-2016 at 08:07 PM

.... I prefer Jameson's...

bezzell - 5-8-2016 at 08:20 PM

that was actually pretty funny Bubbha ... extra serving of sugar today? (you know ... THE most essential nutrient for mankind )
bravo

bajabuddha - 5-8-2016 at 08:23 PM

Never, and I do mean NEVER touch the stuff. Touche.

4x4abc - 5-8-2016 at 08:23 PM

Quote: Originally posted by bajabuddha

and the moon doesn't rotate on its' own axis, but as it travels around us displays only ONE SIDE to the sun....

nope - the moon rotates around it's own axis once in 29 days. And the entire surface of the moon is illuminated once during one 29 day cycle on it's rotation around the sun, however, it displays only one side to earth

https://www.youtube.com/watch?v=_QcgDiF1a14&src_vid=W47W...

still looking for an answer for the original question

bajabuddha - 5-8-2016 at 08:31 PM

Quote: Originally posted by bajabuddha

and the moon doesn't rotate on its' own axis, but as it travels around us displays only ONE SIDE to the sun....

Erm, I believe the earth's gravitational pull holds the moon into a non-axial orbit; it doesn't rotate, but faces us constantly due to our close proximity and gravitational pull. The moon's 'rotation' is due to our gravity, not its' own rotation. I displace your theorems and replace them with one of my own... HAHAHAHAHA! (mythbusters) JUST KIDDING; WHO G / A / F ?? :lol:

BornFisher - 5-8-2016 at 08:36 PM

Ah it`s just all positions. Look now. The moon is a sliver, the sun has just set. If you go WAY out in outer space, you will see a full moon. There is always a full moon somewhere out there, even if it`s Mark or Jeff dropping their pants!!!
BUT the real deal is coming fast. That would be the moon getting between the earth and sun. This will happen August in 2017. Going clear across the USA. The most watched solar eclipse EVER!!!!
Make your plans now, and don`t settle for 99%. It HAS to be 100% to see the Corona Beer!!!!

Seriously I can`t give the science answer but could give a sitting around the campfire answer by pointing here and there.
Remember on the full moon, the sun sets as the moon rises. And solar eclipses only will happen on a new moon.

4x4abc - 5-8-2016 at 09:15 PM

Quote: Originally posted by BornFisher

Remember on the full moon, the sun sets as the moon rises. And solar eclipses only will happen on a new moon.

and all lunar eclipses will happen during a full moon

bajabuddha - 5-8-2016 at 09:18 PM

nope - the moon rotates around it's own axis once in 29 days.

still looking for an answer for the original question

IF the moon rotated on its own axis every 29 days, and facing the earth at a constant; my pea-brain sez "THAT DOES NOT COMPUTE". If for a fact the moon faces us constantly, AND rotates, wouldn't we see other sides of it? Sounds to me like the poor ol' rock is locked to us like Palin to Alaska (no offense, northern neighbors). We'll see the same smilin' face telling us fables for eternity. So how is it rotating on its' axis??? It ROTATES THE EARTH APROXIMATELY 29 DAYS mas o meno. It's all kinda like old age; one day you wake up and say, '' AW, SHUCKS, GRAVITY WORKS!".

To your original question; due to the elliptical orbit of the moon around the earth, there's always a slight penumbra of the earth's shadow on the moon. You don't always see 100%; just some people have to quibble. Did I win yet, or are you still gonna play professor? :yawn:

wessongroup - 5-8-2016 at 09:50 PM

Super picture ... simply outstanding ... thanks much

lunar libration

"It’s common knowledge that our moon has a nearside and a farside. One half of the moon always faces Earth, and one half always points away. Does this mean we can only see 50% of the moon’s surface from Earth? No. In fact, over time, it’s possible to see as much as 59% of the moon’s surface, due to a slight north-south rocking and east-west wobbling of the moon known as lunar libration. Follow the links below to learn more:"

http://earthsky.org/space/how-much-of-the-moon-can-we-see-fr...

Knew we could see 50% ... had to look up the other

Thanks again ... for a great question and such a great picture

[Edited on 5-9-2016 by wessongroup]

bajabuddha - 5-8-2016 at 10:36 PM

Definition of libration~

1: an oscillation in the apparent aspect of a secondary body (as a planet or a satellite) as seen from the primary object around which it revolves.

wow.

A whole NINE PERCENT. Now, that's impressive. Oscillating, which means there's probably a nine-percent loss from the original 50% as well, which either means we see 4.5% of BOTH sides, or 9% of either side, which would mean we'd be seeing 72% OF THE TOTAL MOON'S SURFACE!!!! OK, which is it?

Whew, glad we got that all cleared out for the night-time scholars out there.

And all this time I thought 'librations' was a form of liquid entertainment, or oscillatory entertainments of the 'toy' variety, found in many Ensenada motels.

Man, I love this Chit! What else can you entertain yourself with after late-nite TV?????????? :bounce:

4x4abc - 5-8-2016 at 10:59 PM

here is your rotation answer:
https://www.youtube.com/watch?v=OZIB_leg75Q

4x4abc - 5-8-2016 at 11:07 PM

so, both earth and the moon are rotating around the sun
earth's pattern is pretty simple
but the moon's path is cool:

http://tube.geogebra.org/m/HqK3sujy

bajabuddha - 5-9-2016 at 03:25 AM

Wow. I also heard there's a ring around Uranus.

http://www.proctoscopy.org

Mexitron - 5-9-2016 at 06:19 AM

Moon rotates in (serendipitous or causal) synchronistic orbit with earth. Seeing only half or quarter or whatever phase is just the relative positioning with our viewpoint. Half of the Moon is always lit, just like Earth.

David K - 5-9-2016 at 06:49 AM

The "dark side of the moon" is also a misnomer as it gets as much sunlight each month as the side which always faces the earth.

4x4abc - 5-9-2016 at 08:25 AM

Quote: Originally posted by Mexitron

Moon rotates in (serendipitous or causal) synchronistic orbit with earth. Seeing only half or quarter or whatever phase is just the relative positioning with our viewpoint. Half of the Moon is always lit, just like Earth.

you are on to something

BooJumMan - 5-9-2016 at 02:53 PM

Trying to understand the question. Could another way to ask it be: "Why is the moon not always full?"

4x4abc - 5-9-2016 at 03:34 PM

Trying to understand the question. Could another way to ask it be: "Why is the moon not always full?"

it's always full - but not from our perspective

BooJumMan - 5-9-2016 at 05:02 PM

Yes of course, I meant from our perspective "full". Just questioning the question to answer correctly.

"I ask why on most days we see only part of the moon".

Part of the moon...as it part lit (phases), or just always the same area/side of the moon?

If why we only see the same "side" of the moon, it is because the rotation/spin of the moon is equal to the orbital velocity of the moon around the earth. Or is that still not what you're looking for? Ha. Sorry I'm a aerospace engineer and love physics and space, and just don't know what "part" refers to.

[Edited on 5-10-2016 by BooJumMan]

SFandH - 5-9-2016 at 05:18 PM

Trying to understand the question. Could another way to ask it be: "Why is the moon not always full?"

it's always full - but not from our perspective

Always? Not during a lunar eclipse, when it is in the earth's shadow.

4x4abc - 5-9-2016 at 06:11 PM

Quote: Originally posted by SFandH

Trying to understand the question. Could another way to ask it be: "Why is the moon not always full?"

it's always full - but not from our perspective

Always? Not during a lunar eclipse, when it is in the earth's shadow.

damn - you are good!

4x4abc - 5-9-2016 at 06:14 PM

Yes of course, I meant from our perspective "full". Just questioning the question to answer correctly.

"I ask why on most days we see only part of the moon".

Part of the moon...as it part lit (phases), or just always the same area/side of the moon?

If why we only see the same "side" of the moon, it is because the rotation/spin of the moon is equal to the orbital velocity of the moon around the earth. Or is that still not what you're looking for? Ha. Sorry I'm a aerospace engineer and love physics and space, and just don't know what "part" refers to.

[Edited on 5-10-2016 by BooJumMan]

I had already noticed my careless language and corrected the original question:

Why do we see only part of the moon illuminated by the sun most days?
Like in the image above, we also see the part that is illuminated by earth.
And like any other object in the universe, we never see more than 1/2.

woody with a view - 5-9-2016 at 07:00 PM

Is it because the sun provides the light and the shadows play tricks on our perception of said light?

4x4abc - 5-9-2016 at 08:53 PM

here is the easiest approach:

we have 3 things - a source of light (the sun), an object (the moon), an observer on earth (you and I)

earth rotates once around itself towards the east in 24 hours
the moon orbits earth eastward and it moves a little faster than earth
therefore the moon has a different position in the sky every day
that makes the angles between the 3 change every day

the answer: we see only part of the lit moon from our perspective due to the changing angles between moon and earth.

the easy one:
full moon
from our prospective sun and moon are 180 degrees apart (we are in the middle - all 3 are in one line
sun sets, full moon rises
lets assume it's a perfect day night balance, 6 am sun up, 6 pm sun down
then the full moon will be visible the entire night of 12 hours

the next day the almost full moon (waning) will rise at about 7 pm - about one hour (exact 53 min) darkness, 11 hours 7 minutes moonlight

skip to (third quarter) half moon,
half moon will rise at exactly 12 am (6 hours of darkness before, followed by 6 hours of moonlight)
moon will be lit from the bottom at 12 am, because the sun is in the south below the horizon
at 6 am the moon will be exactly in the south (90 degree angle to the sun)
lit from the left because the sun rises at this time in the east
moon will be visible in the day sky until 12 noon

new moon: entire night will be in darkness
moon is between earth and sun (0 degrees angle)

waxing crescent moon (2 days old): visible right before the 6 pm sunset - and a little after sunset, rest of the night will be in total darkness

first quarter half moon:
moon rises at 12 pm
at 6 pm the moon will be exactly in the south
90 degree angle to the sun setting in the west
moon will be 6 hours in the night sky, rest of the night is dark
when the moon sets at 12 am, it will be lit from the bottom

[Edited on 5-10-2016 by 4x4abc]

[Edited on 5-10-2016 by 4x4abc]

wessongroup - 5-9-2016 at 09:06 PM

I'll never look at the moon the same

4x4abc - 5-9-2016 at 09:46 PM

we do a campfire game on occasion

10 feet away from whoever is watching put a water melon on a tripod (apple works as well)
someone shines a flashlight onto the melon
flashlight behind audience = full moon (melon)
flashlight right of audience (90 degrees) = 1st quarter half moon (melon)
flashlight left of audience (90 degrees) = 3rd quarter half moon (melon)
and anything in between

here is a 1st quarter half apple:
https://carlosnpainter.smugmug.com/Travel/2014-04-13-Pily-an...

Barry A. - 5-9-2016 at 10:18 PM