Summer Moon

[Uilleann]

A quick side-of-the-road snap from late summer. Saw the color pop as the very young moon was setting, and pulled off the freeway quickly to snap this one. Jupiter and Saturn also popped by for an appearance. Love these desert skies!

[drk]

Awesome!

Uilleanne, help me with this. I think for the most part the moon and earth are considered a double planetary system. Do you hear this?

Secondly: consider the shadow of the curvature of the earth so perfectly matches the curvature of the surface of the moon. Also consider how completely perfect that the moon can eclipse the sun.

What do you make of these facts?

[Steve Machol]

Very nice!

[Uilleann]

Awesome!

Uilleann, help me with this. I think for the most part the moon and earth are considered a double planetary system. Do you hear this?

Secondly: consider the shadow of the curvature of the earth so perfectly matches the curvature of the surface of the moon. Also consider how completely perfect that the moon can eclipse the sun.

What do you make of these facts?

Firstly: I've not heard the Earth-Moon system referred to as a "double planetary" system before. My understanding is that because the orbital barycenter of the Earth-Moon system lies inside the body of the Earth, that it doesn't meet the standard of a double planetary system. Pluto and Charon however, do, and are the only double system that I know of in our solar system.

Second: Remeber also that it's not the curvature of the earth's shadow we're seeing on the side of the moon when we see those very young and very old crescents. That's simply the terminator - the line between daylight and darkness. It appears curved to our eye because of the curvature of the moon itself, and our position "behind" it during those phases. An optical illusion of sorts.

Third: The fact that the angular size of the moon and the sun appear so close in our sky really is pretty wild given their massive differences in size! That's the beauty of seeing an object at a mere 250,000 miles - vs 93,000,000 miles! That's also why PALS work better when closer to the eye - those narrow corridors appear "larger". If you EVER have a chance to view a total solar eclipse live - DO IT. I cannot stress that enough. Even for this seasoned amateur astronomer, it was absolutely a life-changing event to witness!

Fourth: I know you didn't ask, but were thinking it. Pink Floyd's Dark Side of the Moon IS in fact one of the greatest albums of all time. Period. Fight me. :spin:

Very nice!

Thank you as always Steve! I'll never not be in love with out amazing skies out here! Hope all is well with you, and yours friend!

[drk]

Nice! Did not know those things.

[AngeHamm]

Magnificent shot. I hope you get some pics of the eclipse next week.

Some astronomers do, in fact consider the earth and Moon to be a "double planet." They categorized Pluto and Charon the same way, back when Pluto was considered one of the major planets. The thinking is that the Moon is proportionately much closer to the size of the Earth than any other moon-planet pairings in the solar system. The Moon affects the Earth several orders of magnitude more than, say, Ganymede affects Jupiter.

The near-perfect match of the visible sizes of the sun and moon is one of the most interesting things about the universe to me. The Moon, of course, was spun off the Earth by a massive impact with a Mars-sized protoplanet in our solar system's early days. As a result, the Moon is measurably drifting farther away from Earth with every orbit and will one day escape entirely and spin its way off into the cosmos. During the Jurassic period, the Moon was three times wider across in the sky. Imagine those solar eclipses! Ten times more frequent with totality lasting almost an hour. Imagine what the stegosaurs must have thought! What this means for us is that the Moon was at exactly the right distance from the Earth to match the Moon's diameter just in time for humanity to evolve to notice, revere, and measure it. This incredibly unlikely cosmic coincidence is one of the big science reasons I believe in a creator God. That timing is just too good to be an accident.

[AngeHamm]

Also, start making your plans now for April 8, 2024.

https://www.greatamericaneclipse.com/april-8-2024

[Uilleann]

Magnificent shot. I hope you get some pics of the eclipse next week.

Some astronomers do, in fact consider the earth and Moon to be a "double planet." They categorized Pluto and Charon the same way, back when Pluto was considered one of the major planets. The thinking is that the Moon is proportionately much closer to the size of the Earth than any other moon-planet pairings in the solar system. The Moon affects the Earth several orders of magnitude more than, say, Ganymede affects Jupiter.

The near-perfect match of the visible sizes of the sun and moon is one of the most interesting things about the universe to me. The Moon, of course, was spun off the Earth by a massive impact with a Mars-sized protoplanet in our solar system's early days. As a result, the Moon is measurably drifting farther away from Earth with every orbit and will one day escape entirely and spin its way off into the cosmos. During the Jurassic period, the Moon was three times wider across in the sky. Imagine those solar eclipses! Ten times more frequent with totality lasting almost an hour. Imagine what the stegosaurs must have thought! What this means for us is that the Moon was at exactly the right distance from the Earth to match the Moon's diameter just in time for humanity to evolve to notice, revere, and measure it. This incredibly unlikely cosmic coincidence is one of the big science reasons I believe in a creator God. That timing is just too good to be an accident.

I still believe the Earth - Moon system is catagorically not considered a double planetary system due to the location of the orbital barycenter. That's the astronomically accepted defining characteristic of a true double planet - at least so far. With that said, I'll *always* think of Pluto as a true planet, and never fully agree to it's demotion to a "minor planet". BOO! ;)

The moon was closer millions of years ago, and did in fact appear larger in the sky - but nothing on the order that is commonly thrown around the internet. 85 million years ago, the moon was a bit over 3,200 km closer than today (the average orbit today is about 386,000 km from us so barely a drop in the bucket distance wise), making it appear only 0.8% larger in the sky. Not an amount perceptable by our eyes certainly.

Regardless of the math, I too find the earth moon system we live within to be fascinating. Perhaps interestingly, my study of the cosmos has solidified my atheism, and allowed me to appreciate the vastness of the universe, it's amazing complexity, and forced me to examine things from a decidedly non-athropocentric, or theocentric point of view. Whatever the ultimate reality may be - it's a damn priviledge to get to share this little corner of space with all of yinz! :D

[drk]

I still believe the Earth - Moon system is catagorically not considered a double planetary system due to the location of the orbital barycenter. That's the astronomically accepted defining characteristic of a true double planet - at least so far. With that said, I'll *always* think of Pluto as a true planet, and never fully agree to it's demotion to a "minor planet". BOO! ;)

The moon was closer millions of years ago, and did in fact appear larger in the sky - but nothing on the order that is commonly thrown around the internet. 85 million years ago, the moon was a bit over 3,200 km closer than today (the average orbit today is about 386,000 km from us so barely a drop in the bucket distance wise), making it appear only 0.8% larger in the sky. Not an amount perceptable by our eyes certainly.

Regardless of the math, I too find the earth moon system we live within to be fascinating. Perhaps interestingly, my study of the cosmos has solidified my atheism, and allowed me to appreciate the vastness of the universe, it's amazing complexity, and forced me to examine things from a decidedly non-athropocentric, or theocentric point of view. Whatever the ultimate reality may be - it's a damn priviledge to get to share this little corner of space with all of yinz! :D

What would you say if you considered the magnitude of scale is just about as vast looking downwards in size vs looking outwards in size?

In fact we inhabit the "middle" of scale, roughly.

https://www.nikon.com/about/sp/universcale/

https://futurism.com/interactive-scale-universe

[drk]

Imagine what the stegosaurs must have thought!

Unfortunately the stegosaur's brain volume was the size of a wad of chewing gum! Or 1-800's Brad Scott.

[Uilleann]

What would you say if you considered the magnitude of scale is just about as vast looking downwards in size vs looking outwards in size?

In fact we inhabit the "middle" of scale, roughly.

https://www.nikon.com/about/sp/universcale/

https://futurism.com/interactive-scale-universe

Not sure I follow here - I think it can get pretty sketchy, quickly, to allow human centered thought processes/positioning into our understanding of the universe. It's very easy to think of courselves as the center of everything (just look at everything we "knew" astronomically in pre-Copernican times as an example. Though I also believe we've hardly even scratched the sirface of all there is to know about the cosmos. While that's a daunting thought, I also find that really really cool!

[drk]

Here's the point: I am easily astounded by the scale of things, when looking out. It's natural to say: "Wow...the universe is so big, and I'm so small!"

How often do we say: "Wow, the universe is so small, and I'm so big"?

It gives a different philosophical perspective. We are somewhere in the middle, actually, in scale of the universe.

[Uilleann]

Here's the point: I am easily astounded by the scale of things, when looking out. It's natural to say: "Wow...the universe is so big, and I'm so small!"

How often do we say: "Wow, the universe is so small, and I'm so big"?

It gives a different philosophical perspective. We are somewhere in the middle, actually, in scale of the universe.

I think I'm pickin up what you're layin down here Doc. Perhaps summed up nicely in some favorite quotes:

“The cosmos is within us. We are made of star-stuff. We are a way for the Cosmos to know itself.”

-Carl Sagan

& similarly:

"We are the cosmos mae conscious, and life is the means by which the universe understands itself."

-Brian Cox