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Science Section => Science General Discussion => Topic started by: Unbeliever on July 21, 2019, 06:46:26 PM

Title: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on July 21, 2019, 06:46:26 PM
The Rare Earth hypothesis is looking stronger all the time.


https://www.youtube.com/watch?v=7o3hDRW072o
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Hydra009 on July 21, 2019, 08:12:26 PM
A small fraction times trillions is still a pretty big number.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on July 22, 2019, 02:09:46 PM
Might depend on just how small the fraction is, and that's what we don't know. I can't believe in ETI until at least some kind of evidence comes in to support the hypothesis. Like God: no evidence, no belief.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Hydra009 on July 22, 2019, 02:17:13 PM
Might depend on just how small the fraction is, and that's what we don't know. I can't believe in ETI until at least some kind of evidence comes in to support the hypothesis. Like God: no evidence, no belief.
Of course.  No one is saying otherwise.

Though the universe being empty of life except for Earth would be a bit like being on a small island and venturing out and finding no other life on the entire planet.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: aileron on August 04, 2019, 09:38:16 PM
You can pool knowledge, but you can't pool ignorance. We're simply too ignorant to form any meaningful estimate of how likely extraterrestrial life or intelligence are.

When asked his "gut feel" Carl Sagan replied that he tries not to think with his gut. When asked his hypothesis of why rocks in mountains have embedded seashells, Thomas Jefferson responded that "I don't know" is a more accurate answer than offering speculation without any reason for the speculation.

Except for the folks who know for certain they've gotten an alien abduction probe, I think we're in the position where Sagan's and Jefferson's advice is sage.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 08:09:20 AM
You can pool knowledge, but you can't pool ignorance. We're simply too ignorant to form any meaningful estimate of how likely extraterrestrial life or intelligence are.

When asked his "gut feel" Carl Sagan replied that he tries not to think with his gut. When asked his hypothesis of why rocks in mountains have embedded seashells, Thomas Jefferson responded that "I don't know" is a more accurate answer than offering speculation without any reason for the speculation.

Except for the folks who know for certain they've gotten an alien abduction probe, I think we're in the position where Sagan's and Jefferson's advice is sage.

Jefferson did fail at ... he didn't believe it possible that meteorites (the rocks) came from outer space.  He thought them terrestrial.  So in that case he claimed knowledge illegitimately, and wrongly.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 08:27:06 AM
The Rare Earth hypothesis is looking stronger all the time.

Oddly, I've been learning the opposite lately.  The habitable zone of our own solar system is expanding to include some moons with planetary-generated heat (tidal friction for example).  And with more earth-like planets being discovered every year, I suspect life abounds. 

Not necessarily intelligent self-aware life (that's still "iffy"), but I bet pond scum is almost standard wherever conditions permit (and those are now multitudes).  Complex life (eukaryotes and other multi-cellular organisms) seems to have happened here rather easily, so why not most similar situations? 

After that, natural selection takes over anywhere.  I don't mean there would have to be reptiles and dinosaurs and mammals (though the basic patterns make sense) or even anything homonid.  Self-awareness might be a huge jump.

But given the ease of simple cells and the evolutionary pressures to live and reproduce at even the basic levels, and the number of planets out there with the right conditions, I suspect we are not alone. 

The more interesting question might be not "if" there are other intelligences but who can contact something else across spacetime in a way that is recognizable...
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 08:29:20 AM
Might depend on just how small the fraction is, and that's what we don't know. I can't believe in ETI until at least some kind of evidence comes in to support the hypothesis. Like God: no evidence, no belief.

I agree, but give some attention to the likelihood through quantity of sheer numbers.  And no, I don't think we have been visited.  It might be just too difficult.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 08:30:34 AM
You can pool knowledge, but you can't pool ignorance.

My apologies, but tell that to Trump, LOL!
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: josephpalazzo on August 05, 2019, 09:50:54 AM
A small fraction times trillions is still a pretty big number.

Back in the 50's - I was a young rooster back then - Enrico Fermi made that calculation, and concluded the earth should have been visited a long time ago, many times over. So he shouted in the middle of the cafeteria of the Los Alamos National Laboratory, "Where are they? Where is everybody?" There's also the theory that if aliens know we exist, they would want to kill us. But also if we know they exist we would want to kill them. So the best policy is to shut up and pretend we don't exist. Hence the GREAT SILENCE.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 11:40:54 AM
Back in the 50's - I was a young rooster back then - Enrico Fermi made that calculation, and concluded the earth should have been visited a long time ago, many times over. So he shouted in the middle of the cafeteria of the Los Alamos National Laboratory, "Where are they? Where is everybody?" There's also the theory that if aliens know we exist, they would want to kill us. But also if we know they exist we would want to kill them. So the best policy is to shut up and pretend we don't exist. Hence the GREAT SILENCE.

All great scientists seem to fins a really bad idea and defend it to their deaths.  The idea that we should have been visited by aliens by know is one of those.  There are sevela objects that come easily to mind.

1.  Non interference.  IOW, don't bother any planet with at least pond scum that can't talk "interstellar" yet.
2.  Hide while observing.  We can fool ducks with camoflauge.  "They" could do it better.
3.  Hide in open sight.  I might be an alien observing all of you for trends toward insterstellar threats.
4.  We're the first.  Someone has to to be.
5.  We're the last.  And stupidest.  Someone has to be.
6.  No one found us.  It's a VERY big Universe.
7.  Everyone creates their own universe where they are alone.  Proof me wrong.
8.  The Borg or the Q killed all the others and do (or do not) know about us yet.
9.  They read our superhero comic books and scared to death of us.  Don't laugh, that was a comic book plot once.
10.  We are on the wrong channel.  1420 to 1720 MHzis the interstellar PBS channel and no one "out there" actually watches it.

I could go on...
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 12:05:48 PM
Back in the 50's - I was a young rooster back then - Enrico Fermi made that calculation, and concluded the earth should have been visited a long time ago, many times over. So he shouted in the middle of the cafeteria of the Los Alamos National Laboratory, "Where are they? Where is everybody?" There's also the theory that if aliens know we exist, they would want to kill us. But also if we know they exist we would want to kill them. So the best policy is to shut up and pretend we don't exist. Hence the GREAT SILENCE.

When the first pulsar signal was detected in ... 1969? ... that was the plan.  It took awhile to realize it was natural.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 12:07:04 PM
All great scientists seem to fins a really bad idea and defend it to their deaths.  The idea that we should have been visited by aliens by know is one of those.  There are sevela objects that come easily to mind.

1.  Non interference.  IOW, don't bother any planet with at least pond scum that can't talk "interstellar" yet.
2.  Hide while observing.  We can fool ducks with camoflauge.  "They" could do it better.
3.  Hide in open sight.  I might be an alien observing all of you for trends toward insterstellar threats.
4.  We're the first.  Someone has to to be.
5.  We're the last.  And stupidest.  Someone has to be.
6.  No one found us.  It's a VERY big Universe.
7.  Everyone creates their own universe where they are alone.  Proof me wrong.
8.  The Borg or the Q killed all the others and do (or do not) know about us yet.
9.  They read our superhero comic books and scared to death of us.  Don't laugh, that was a comic book plot once.
10.  We are on the wrong channel.  1420 to 1720 MHzis the interstellar PBS channel and no one "out there" actually watches it.

I could go on...

Galactic Dems killed Galactic PBS (loss of pledges).  Same as on Earth.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on August 05, 2019, 03:32:09 PM
And with more earth-like planets being discovered every year, I suspect life abounds. 


Keep in mind that "earth-like" doesn't really mean "like the Earth," it just means not a gas giant, like those in the outer system: Mercury, Venus and Mars would be considered "earth-like" if they were in another system, but they're very little like our watery, green planet.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on August 05, 2019, 03:34:43 PM
I agree, but give some attention to the likelihood through quantity of sheer numbers.  And no, I don't think we have been visited.  It might be just too difficult.

Yeah, I think it's much harder to travel through that immense void than most people think. Both in terms of time and energy, it seems just too hard for anything to get from star to star without really extreme motivation.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on August 05, 2019, 03:37:06 PM
All great scientists seem to fins a really bad idea and defend it to their deaths.  The idea that we should have been visited by aliens by know is one of those.  There are sevela objects that come easily to mind.

1.  Non interference.  IOW, don't bother any planet with at least pond scum that can't talk "interstellar" yet.
2.  Hide while observing.  We can fool ducks with camoflauge.  "They" could do it better.
3.  Hide in open sight.  I might be an alien observing all of you for trends toward insterstellar threats.
4.  We're the first.  Someone has to to be.
5.  We're the last.  And stupidest.  Someone has to be.
6.  No one found us.  It's a VERY big Universe.
7.  Everyone creates their own universe where they are alone.  Proof me wrong.
8.  The Borg or the Q killed all the others and do (or do not) know about us yet.
9.  They read our superhero comic books and scared to death of us.  Don't laugh, that was a comic book plot once.
10.  We are on the wrong channel.  1420 to 1720 MHzis the interstellar PBS channel and no one "out there" actually watches it.

I could go on...

I'm partial to #4, myself. We may well be the first life to achieve intelligence.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 03:53:35 PM

Keep in mind that "earth-like" doesn't really mean "like the Earth," it just means not a gas giant, like those in the outer system: Mercury, Venus and Mars would be considered "earth-like" if they were in another system, but they're very little like our watery, green planet.

Well, I DO mean "Earth-like" in the sense of having an atmosphere, a magnetosphere, and liquid water at some place.  I don't really consider Venus or Mars to be "earthlike" in that regard now of course.  Though they might have been and one time for a while. 

And I can't give a list of earthlike planets elsewhere.  But there do seem to be some from current reports and some Solar moons do have conditions that could support life as we know it.

Partially, I'm going from the statistics rule.  There can be none of something, one of something, or many of something.  What there can't be is just 2 of something.  So, if there are conditions for life (Europa and Enceladus for example), then it seems likely that there are very many such places elsewhere.

I make no claim that there IS intelligent life elsewhere, just that conditions from which it could arise exist.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: aileron on August 05, 2019, 03:55:01 PM
Jefferson did fail at ... he didn't believe it possible that meteorites (the rocks) came from outer space.  He thought them terrestrial.  So in that case he claimed knowledge illegitimately, and wrongly.

Jefferson didn't have the benefit of Google. If he had it, he'd probably have known that the ancient Egyptians knew for certain that meteorites came from the sky. They called iron the "metal from heaven" because before people figured out how to identify iron ore and smelt it, meteorites were the only source of the metal.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on August 05, 2019, 03:57:00 PM
Well, there are no reasons that I'm aware of that intelligent life can't exist out there, but I know of no other planets or moons where life as we know it can exist. Large numbers of stars and star systems just don't constitute evidence for me.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 04:06:29 PM
I'm partial to #4, myself. We may well be the first life to achieve intelligence.

That is a perfectly reasonable possibility.  But there are the others...
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 05, 2019, 04:14:32 PM
Jefferson didn't have the benefit of Google. If he had it, he'd probably have known that the ancient Egyptians knew for certain that meteorites came from the sky. They called iron the "metal from heaven" because before people figured out how to identify iron ore and smelt it, meteorites were the only source of the metal.

There are even good observations of that.  I recall reading about some ancient Europeans who personally witnessed meteors falling onto their farmland.  I can't provide a date and place, but I know the source was reputable.  That's enough for casual discussion.  Some Googling would find it.

BTW, NASA once announced that the Voyager missions only worked because of the specific planetary alignment.  The last time it had happened was during President Jefferson's administration.  And as they joked, "he blew it".
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 06:49:07 PM
Jefferson didn't have the benefit of Google. If he had it, he'd probably have known that the ancient Egyptians knew for certain that meteorites came from the sky. They called iron the "metal from heaven" because before people figured out how to identify iron ore and smelt it, meteorites were the only source of the metal.

Pagan bullshit.  We all know aliens built the Pyramids ;-)
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 06:49:29 PM
I'm partial to #4, myself. We may well be the first life to achieve intelligence.

Not yet.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 06:50:14 PM
Yeah, I think it's much harder to travel through that immense void than most people think. Both in terms of time and energy, it seems just too hard for anything to get from star to star without really extreme motivation.

Garlic breath?
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 05, 2019, 06:57:17 PM
There are even good observations of that.  I recall reading about some ancient Europeans who personally witnessed meteors falling onto their farmland.  I can't provide a date and place, but I know the source was reputable.  That's enough for casual discussion.  Some Googling would find it.

BTW, NASA once announced that the Voyager missions only worked because of the specific planetary alignment.  The last time it had happened was during President Jefferson's administration.  And as they joked, "he blew it".

Yes, in France, in the 1700s.  The experts said the peasants were drunk that day.

https://www.smithsonianmag.com/smart-news/1803-rain-rocks-helped-establish-existence-meteorites-180963017/
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Unbeliever on August 05, 2019, 07:03:40 PM
Yeah, and El Guapo didn't think gringos could fall from the sky, either, until one of them did! LOL




https://www.youtube.com/watch?v=1l7e9BD_gos
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: trdsf on August 26, 2019, 07:41:19 PM
Wow, a lot of unwarranted assumptions and just plain sloppy nonsense in this piece.

0:45 -- "The major difference between our planet and pretty much all of the other major exoplanets we've discovered so far and most importanly planets in our own solar system is that our planet has a very very large satellite/partner that technically doesn't qualify as a moon."

We know next to nothing about the satellites around exoplanets.  Earth-sized planets are difficult enough to spot; moon-sized moons even more so; so far there are over 4100 confirmed exoplanets, four exoplanet candidates (three of which are larger to MUCH larger than the Earth), and zero confirmed exomoons.  Our state of knowledge about how common Moon-sized natural satellites are is effectively nil.

As far as our own planetary system goes, there are four moons larger and two only slightly smaller.  Hardly alone in its class.  Relative to the size of its primary, the Moon is far outclassed by Charon relative to Pluto.  In fact, the Pluto-Charon system is arguably a double (dwarf) planet, since the center of gravity lies in space between the two bodies, not inside the primary as for all other planets in this system.

I won't even dignify 'doesn't technically qualify as a moon' with any more than that he needs to check the expiration date on his vodka.  That is one of the stupidest statements I have heard in an allegedly factual video.

Moving on:

1:52 -- yes, we see a lot of "super-earths", of which none happen to be in our system, because they're easier to detect than an earth-sized planet.  Also, 4100 planets in a galaxy of some 250 billion stars.  Not a statistically significant sample, and skewed towards the huge and/or highly elliptical planets because they are a lot easier to find, and we're only just at the beginning of finding them.

2:50 -- and this is where I lost the will to live.

Yes, we've discovered a lot of hot Jupiters because those are the easiest planets to discover.  They make the largest doppler shifts in their suns' spectra, they occult more light than a distant gas giant because they're closer and take up a larger portion of the stellar disk when they transit.

I couldn't be bothered with the rest of it.  It's all based on the obviously false assumption that we, at the very beginning of our ability to detect exoplanets, are detecting everything there is in every star system we look at.  Also, why is he making the assumption that every other planetary system should look like ours?  We don't have anywhere near enough data to be able to start making judgments about which systems are 'typical' and which are 'strange'.

You know what?  I've studied light curves; I've gone through at least hundreds, possibly more than a thousand, in the Kepler data, and telling signal from noise is not always obvious... and as it happens, I have co-discovered one exoplanet.  And the data one has to try to sort out is very rarely clean and clear, like this:
(https://panoptes-uploads.zooniverse.org/production/project_attached_image/d826c055-e4a1-47be-a4f2-6c92feb78183.png)

Usually it's more like this:
(https://panoptes-uploads.zooniverse.org/production/project_attached_image/670d9d6d-7361-4f8f-997e-79bfe230139d.png)

So, speaking as someone who has been there and has done that, I have no hesitation in declaring this video just plain wrong.  It's a total and profound failure of scientific imagination, and a completely improper extrapolation of current data.  You could declare any fully characterized solar system as 'weird' when compared against incompletely-understood other systems.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: trdsf on August 26, 2019, 08:04:35 PM
Back in the 50's - I was a young rooster back then - Enrico Fermi made that calculation, and concluded the earth should have been visited a long time ago, many times over. So he shouted in the middle of the cafeteria of the Los Alamos National Laboratory, "Where are they? Where is everybody?" There's also the theory that if aliens know we exist, they would want to kill us. But also if we know they exist we would want to kill them. So the best policy is to shut up and pretend we don't exist. Hence the GREAT SILENCE.
Fermi's paradox is only a paradox in an eternal steady-state universe -- which was, of course, a valid theory of the universe at the time Fermi posed it.

In a big bang universe, it's not unreasonable to think that you may actually need around nine or ten billion years to build up enough supernova debris to make rocky planets with enough chemical resources for first life, and then intelligent life to develop.  I strongly doubt you can make life out of hydrogen and helium and vanishingly thin traces of lithium.

And judging by the speed with which life appeared on Earth once it solidified and cooled, and the slowness with which complex life appeared after that, it's also not unreasonable to think that life may be easy, but complex/intelligent life may be difficult.  In a universe that has at least one border in time, that's a very important consideration, especially relative to the Fermi "paradox".
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 26, 2019, 11:56:17 PM
Wow, a lot of unwarranted assumptions and just plain sloppy nonsense in this piece.

0:45 -- "The major difference between our planet and pretty much all of the other major exoplanets we've discovered so far and most importanly planets in our own solar system is that our planet has a very very large satellite/partner that technically doesn't qualify as a moon."

We know next to nothing about the satellites around exoplanets.  Earth-sized planets are difficult enough to spot; moon-sized moons even more so; so far there are over 4100 confirmed exoplanets, four exoplanet candidates (three of which are larger to MUCH larger than the Earth), and zero confirmed exomoons.  Our state of knowledge about how common Moon-sized natural satellites are is effectively nil.

As far as our own planetary system goes, there are four moons larger and two only slightly smaller.  Hardly alone in its class.  Relative to the size of its primary, the Moon is far outclassed by Charon relative to Pluto.  In fact, the Pluto-Charon system is arguably a double (dwarf) planet, since the center of gravity lies in space between the two bodies, not inside the primary as for all other planets in this system.

I won't even dignify 'doesn't technically qualify as a moon' with any more than that he needs to check the expiration date on his vodka.  That is one of the stupidest statements I have heard in an allegedly factual video.

Moving on:

1:52 -- yes, we see a lot of "super-earths", of which none happen to be in our system, because they're easier to detect than an earth-sized planet.  Also, 4100 planets in a galaxy of some 250 billion stars.  Not a statistically significant sample, and skewed towards the huge and/or highly elliptical planets because they are a lot easier to find, and we're only just at the beginning of finding them.

2:50 -- and this is where I lost the will to live.

Yes, we've discovered a lot of hot Jupiters because those are the easiest planets to discover.  They make the largest doppler shifts in their suns' spectra, they occult more light than a distant gas giant because they're closer and take up a larger portion of the stellar disk when they transit.

I couldn't be bothered with the rest of it.  It's all based on the obviously false assumption that we, at the very beginning of our ability to detect exoplanets, are detecting everything there is in every star system we look at.  Also, why is he making the assumption that every other planetary system should look like ours?  We don't have anywhere near enough data to be able to start making judgments about which systems are 'typical' and which are 'strange'.

You know what?  I've studied light curves; I've gone through at least hundreds, possibly more than a thousand, in the Kepler data, and telling signal from noise is not always obvious... and as it happens, I have co-discovered one exoplanet.  And the data one has to try to sort out is very rarely clean and clear, like this:
(https://panoptes-uploads.zooniverse.org/production/project_attached_image/d826c055-e4a1-47be-a4f2-6c92feb78183.png)

Usually it's more like this:
(https://panoptes-uploads.zooniverse.org/production/project_attached_image/670d9d6d-7361-4f8f-997e-79bfe230139d.png)

So, speaking as someone who has been there and has done that, I have no hesitation in declaring this video just plain wrong.  It's a total and profound failure of scientific imagination, and a completely improper extrapolation of current data.  You could declare any fully characterized solar system as 'weird' when compared against incompletely-understood other systems.

I generally agree.  But our moon is so much larger in comparison to our planet that it seems relatively unique so far.

On the other stuff like finding planets like Earth, I agree completely.  It seems likely that there are ones like ours, but are hard to find.    But that's one reason we spend money to build better telescopes.  We humans are driven to explore.

I also agree that we are finding that solar systems are more varied than we ever imagined.  When we first saw our own, it seemed reasonable that it was routine in structure by standard gravitational laws. 
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: trdsf on August 27, 2019, 04:07:39 AM
I generally agree.  But our moon is so much larger in comparison to our planet that it seems relatively unique so far.
Oh, no.  Here's the earth and moon to scale, including distance:
(https://www.wired.com/images_blogs/beyond_the_beyond/2013/08/earth-with-moon.jpg)

And here's Pluto and Charon to scale, including distance:
(https://www.nasa.gov/sites/default/files/thumbnails/image/pluto-and-charon-01.jpg)

Although to be sure, not to the same scale as each other.  Charon is much more massive relative to Pluto than the Moon is relative to the Earth.  The barycenter of the Earth/Moon system is 1700km below the surface of the Earth; that of Pluto and Charon is almost 1000km above Pluto's surface, in space: the two bodies very much orbit each other.  In the Earth/Moon system, the Earth is absolutely the dominant body.

While I'm thinking of it, let's put everything but the sun to the same scale:
(http://i.imgur.com/N6LSOUi.jpg)

Yes, all the planets could fit between the Earth and the Moon.  No, it's probably not a good idea to put them all there.  :)
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 27, 2019, 04:14:19 AM
Oh, no.  Here's the earth and moon to scale, including distance:
(https://www.wired.com/images_blogs/beyond_the_beyond/2013/08/earth-with-moon.jpg)

And here's Pluto and Charon to scale, including distance:
(https://www.nasa.gov/sites/default/files/thumbnails/image/pluto-and-charon-01.jpg)

Although to be sure, not to the same scale as each other.  Charon is much more massive relative to Pluto than the Moon is relative to the Earth.  The barycenter of the Earth/Moon system is 1700km below the surface of the Earth; that of Pluto and Charon is almost 1000km above Pluto's surface, in space: the two bodies very much orbit each other.  In the Earth/Moon system, the Earth is absolutely the dominant body.

While I'm thinking of it, let's put everything but the sun to the same scale:
(http://i.imgur.com/N6LSOUi.jpg)

Yes, all the planets could fit between the Earth and the Moon.  No, it's probably not a good idea to put them all there.  :)

Pluto isn't a planet...
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: trdsf on August 27, 2019, 04:30:08 AM
Pluto isn't a planet...
Dwarf planet.  Even so, Charon is much more massive relatively speaking to its primary.  Even moreso are the binary Trojan asteroids Patroclus and Menoetius, which are nearly the same size as each other at 125 and 112 km, respectively.  Their barycenter is just about halfway between them.

The point is, the Earth's Moon is only the largest natural satellite any terrestrial planet in our system has.  It's neither the largest natural satellite, nor is it the largest satellite relative to it's primary.  The guy in the video was trying to assert that there's something really weird about our moon, and he just doesn't have either the justification to think so, or the data to suggest so.  If we should start getting data from exosystems that suggest Earth-sized worlds don't often have Moon-sized moons, then he can make the assertion with some modicum of justification.  Otherwise, he's on the same ground as the people who saw that Venus was cloud-covered, and "deduced" that it must be a wet jungle world with dinosaurs.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 27, 2019, 04:53:02 AM
Dwarf planet.  Even so, Charon is much more massive relatively speaking to its primary.  Even moreso are the binary Trojan asteroids Patroclus and Menoetius, which are nearly the same size as each other at 125 and 112 km, respectively.  Their barycenter is just about halfway between them.

The point is, the Earth's Moon is only the largest natural satellite any terrestrial planet in our system has.  It's neither the largest natural satellite, nor is it the largest satellite relative to it's primary.  The guy in the video was trying to assert that there's something really weird about our moon, and he just doesn't have either the justification to think so, or the data to suggest so.  If we should start getting data from exosystems that suggest Earth-sized worlds don't often have Moon-sized moons, then he can make the assertion with some modicum of justification.  Otherwise, he's on the same ground as the people who saw that Venus was cloud-covered, and "deduced" that it must be a wet jungle world with dinosaurs.

I think I missed the point of this discussion somewhere.  I think the Earth's Moon has had profound affects on Earth and the development of life on it that are not the same as on Pluto's moons or any rotating asteroids.  Possibly some moons of other planets have sufficient water and heat through gravitational tidal friction or possibly even core heat to support some sort of life. 

What is this argument about? 
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 27, 2019, 07:52:53 AM
Tides.  On a water planet.  Are tides important?  Weak moons make for weak tides.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: trdsf on August 27, 2019, 04:05:49 PM
I think I missed the point of this discussion somewhere.  I think the Earth's Moon has had profound affects on Earth and the development of life on it that are not the same as on Pluto's moons or any rotating asteroids.  Possibly some moons of other planets have sufficient water and heat through gravitational tidal friction or possibly even core heat to support some sort of life. 

What is this argument about?
I'm not entirely sure.  My original point was only that the video was incorrect in assuming there's something special about our moon.

In the first place, we know nothing about the moons of other Earth-sized planets in the galaxy, and in the second place, the only thing it has to recommend it is its proximity.  It has no ocean like Europa, Enceladus, or Ganymede.  It has no atmosphere, weather, or methane lakes like Titan.  It has no volcanism like Io or cryovolcanism like Triton.  It has no ring as has recently been theorized for Saturn's moon Rhea.

It's just a lump of mostly mantle with nothing special about it other than it happens to be our satellite.

Now, you're quite right that it's almost certainly had an important role in both abiogenesis and evolution.  The tidal effects alone -- and the moon was a LOT closer then -- kept the water circulating, brought it in contact with the shores to pick up chance minerals, moved countless random chemical experiments around from the safety of a few meters down in water to the catalytic violence of the surface with its lightning and ultraviolet radiation and heat and a heady proto-organic atmosphere of hydrogen and water and ammonia and methane.

It's supposed that it also helps keep our axis of rotation stabilized, but I'm not sure how unstable they think our daily rotate would be without it.  I mean, other than Uranus, the other seven planets are more or less aligned to a vertical that's not far off that of the sun.  Three cheers for conservation of angular momentum, I guess.

But none of that says that we have a special moon.  We just have the moon that we have, and until we have data on the natural satellites of other terrestrial bodies in the galaxy, we can draw no inferences about its "weirdness".
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Baruch on August 27, 2019, 07:15:23 PM
Yes, it is special.  Has its own book.  "Goodnight Moon …"
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Sal1981 on August 27, 2019, 07:28:39 PM
All great scientists seem to fins a really bad idea and defend it to their deaths.  The idea that we should have been visited by aliens by know is one of those.  There are sevela objects that come easily to mind.

1.  Non interference.  IOW, don't bother any planet with at least pond scum that can't talk "interstellar" yet.
2.  Hide while observing.  We can fool ducks with camoflauge.  "They" could do it better.
3.  Hide in open sight.  I might be an alien observing all of you for trends toward insterstellar threats.
4.  We're the first.  Someone has to to be.
5.  We're the last.  And stupidest.  Someone has to be.
6.  No one found us.  It's a VERY big Universe.
7.  Everyone creates their own universe where they are alone.  Proof me wrong.
8.  The Borg or the Q killed all the others and do (or do not) know about us yet.
9.  They read our superhero comic books and scared to death of us.  Don't laugh, that was a comic book plot once.
10.  We are on the wrong channel.  1420 to 1720 MHzis the interstellar PBS channel and no one "out there" actually watches it.

I could go on...
I'm partial to #4, myself. We may well be the first life to achieve intelligence.
Considering how long it takes for complex & intelligent biological life to form a galactic civilization, and how young, comparatively speaking, our universe is then we are probably the first on the field in our neck of the woods. If the same can occur around red dwarfs, for instance, it will happen a lot of times. We're an outlier in any case.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 27, 2019, 10:23:39 PM
Tides.  On a water planet.  Are tides important?  Weak moons make for weak tides.

Thank you. That clarified things.  Really.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 27, 2019, 10:30:15 PM
I'm not entirely sure.  My original point was only that the video was incorrect in assuming there's something special about our moon.

In the first place, we know nothing about the moons of other Earth-sized planets in the galaxy, and in the second place, the only thing it has to recommend it is its proximity.  It has no ocean like Europa, Enceladus, or Ganymede.  It has no atmosphere, weather, or methane lakes like Titan.  It has no volcanism like Io or cryovolcanism like Triton.  It has no ring as has recently been theorized for Saturn's moon Rhea.

It's just a lump of mostly mantle with nothing special about it other than it happens to be our satellite.

Now, you're quite right that it's almost certainly had an important role in both abiogenesis and evolution.  The tidal effects alone -- and the moon was a LOT closer then -- kept the water circulating, brought it in contact with the shores to pick up chance minerals, moved countless random chemical experiments around from the safety of a few meters down in water to the catalytic violence of the surface with its lightning and ultraviolet radiation and heat and a heady proto-organic atmosphere of hydrogen and water and ammonia and methane.

It's supposed that it also helps keep our axis of rotation stabilized, but I'm not sure how unstable they think our daily rotate would be without it.  I mean, other than Uranus, the other seven planets are more or less aligned to a vertical that's not far off that of the sun.  Three cheers for conservation of angular momentum, I guess.

But none of that says that we have a special moon.  We just have the moon that we have, and until we have data on the natural satellites of other terrestrial bodies in the galaxy, we can draw no inferences about its "weirdness".

Please don't get upset if I claim you just made my argument for me.  But you probably did it better than I could/did.  I will add, though, that our moon has also stabilized our axial tilt and I don't think other moons have done that for their planet.  Otherwise, we might be like Mars tilting a lot more unseasonably.

I would suggest that no other moons came from the planet they orbit, but I can't actually prove that (proof of a negative and all that).
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 27, 2019, 10:35:29 PM
I'm partial to #4, myself. We may well be the first life to achieve intelligence.

Considering how long it takes for complex & intelligent biological life to form a galactic civilization, and how young, comparatively speaking, our universe is then we are probably the first on the field in our neck of the woods. If the same can occur around red dwarfs, for instance, it will happen a lot of times. We're an outlier in any case.

Yeah, I was out on a stretch there.  But sometimes brainstorming is useful.  It's not my usual thought pattern, but occasionally creative thought brings good discussion.  It's possible, but time isn't the best determinant for us.

I would ask why you think "probably" about us being first intelligence.  We aren't the oldest solar system, after all.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: trdsf on August 28, 2019, 11:10:28 AM
Please don't get upset if I claim you just made my argument for me.  But you probably did it better than I could/did.  I will add, though, that our moon has also stabilized our axial tilt and I don't think other moons have done that for their planet.  Otherwise, we might be like Mars tilting a lot more unseasonably.

I would suggest that no other moons came from the planet they orbit, but I can't actually prove that (proof of a negative and all that).
The only point I'm making is not that our moon can't be unusual, but that we don't know what is and isn't unusual for planets like the Earth.  You can't make meaningful judgments based on a single data point.  Until we have a better idea what is and isn't common in stellar systems, it just is what it is: an observation without any context to judge it.

Now, I do happen to think that life bearing planets will be more likely than not to have a moon capable of driving meaningful tides because I think that's important to the process of abiogenesis.  But I don't have any justification to call that anything more than a proposal, or even just a guess.  We can't look to Venus to confirm that because there appear to be other reasons life couldn't get started there.  Finding life -- past or present -- on Mars would be a data point against. I'm not sure that finding life on Europa, Enceladus or Titan would be relevant since those are completely different processes in action there.  Life there, however simple, would be staggeringly important for its own reasons.
Title: Re: 10 Scientific Reasons Why Our Solar System Is Really Weird
Post by: Cavebear on August 31, 2019, 02:42:02 AM
The only point I'm making is not that our moon can't be unusual, but that we don't know what is and isn't unusual for planets like the Earth.  You can't make meaningful judgments based on a single data point.  Until we have a better idea what is and isn't common in stellar systems, it just is what it is: an observation without any context to judge it.

Now, I do happen to think that life bearing planets will be more likely than not to have a moon capable of driving meaningful tides because I think that's important to the process of abiogenesis.  But I don't have any justification to call that anything more than a proposal, or even just a guess.  We can't look to Venus to confirm that because there appear to be other reasons life couldn't get started there.  Finding life -- past or present -- on Mars would be a data point against. I'm not sure that finding life on Europa, Enceladus or Titan would be relevant since those are completely different processes in action there.  Life there, however simple, would be staggeringly important for its own reasons.

OK, I undertand that.  I could be possible that a sizable moon like ours might not even be necessary for life to arise in the ocean.  Hydrothermal vents might have well provided the original conditions instead of tidal pools (I make no decision about that now). 

But we do have a large moon and life arose here.  And there are consequences of a large moon that seem beneficial for life and evolution.  I also agree that is not proof of a large moon assisting causing life to exist on Earth.  But absent proof, corrlation is a starting point.

If and when we find a planet similar to Earth with a similar moon (which I suspect will not be a very common event) and there is or is not life (in the least degree of development), that would be some bit of evidence for or against the idea that a moon is required.

More will be better, and I suspect that improved instrumentation will allow us to answer that question in the next decade or 2.