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A-L-E-X
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22 Jun 2020 04:53

Watsisname wrote:
A-L-E-X wrote:
Source of the post In addition our large moon shielded us from a ton of impactors that could have rendered our planet uninhabitable.

Not really, see last part of post here.  Right now the Moon blocks 0.0005% of asteroids that would hit Earth.  Even in the very distant past when it was much closer to Earth, the most it could block was still much less than 1%.

People often underestimate how small and far away the Moon is. :) It is not a good shield. It has a lot of craters on it, but we don't see all the impacts that Earth had since geologic processes have erased most of them.

Still every little bit counts.  If the moon was much larger it would actually have a negative effect on the development of life.  The tidal forces of the moon were probably more significant though in getting sea life to move onto land.  The most important factor here isn't the actual size of the moon but the proportional difference relative to the earth, which is the closest to a double planet, outside of Pluto (which is no longer considered a planet anyway.)  If we want to talk about absolute size, Jupiter was probably the best shield, especially because it actually used to be closer to the sun in the primordial solar system and migrated to its current position later on.
About my point on intelligence, I would like to expand on that.  Based on my conversations with biologists who actually work with these animals, we do a huge disservice when we dont recognize their intelligence.  They even argue with me when I mention that higher animals have the intelligence of a 5 year old child and tell me that dolphins, elephants, bonobos, chimps, gorillas, grey parrots, etc., have intelligence and emotions and empathy that parallels our own.  It's just expressed differently- like a different language.  They are magnificent examples of parallel evolution, which the dinosaurs of the later Cretaceous also experienced.  People who dont give credit to animals for their intelligence are speciests and are a major reason why animals have been mistreated and abused (even by some scientists during experimentation.)  We can also extrapolate this to theorize that in the universe there can be types of difference vastly different from our own, that dont require a large centralized brain.  An example of this is the ant, they have large complex social structures, even keep aphids as pets, and have large nurseries.  There are even signs of intelligence at the unicellular level (amoebas) and many socalled artificial human structures mimic what the slime mold is able to do.  Not only that, but according to some, like Fred Hoyle, we can envision intelligence that doesn't even require a planet for propagation (hive intelligence in the form of interstellar dust or even pure energy.)  My reason for thinking that technological civilizations are very rare is not because human beings are somehow rare and special (this is the mistake made by people who fall for the Anthropic Principle- same reason why I think there are infinite universes), it's because technology and industry are destructive to the species that develops it.  We can see this with humanity quite easily.....I felt this way 30 years ago and everything I've seen in those 30 years shows me I was right.  Industrial farming techniques have depleted nutrients from the soil and damaged the environment (as India and Africa are now finding out), nasty pollution and overpopulation of humans has resulted in the sixth mass extinction in the planet's history, and average human's ignorance of these issues makes me doubt the actual intelligence of humans.  Human nature itself (greed rather than being cooperative like ants, warlike nature, short term benefits gained by sacrificing long term goals) is self destructive and it's the height of arrogance and ignorance for people to consider themselves to be somehow specially intelligent....I even find the so-called "scientific name" of homo sapiens "man the wise"? to be a ridiculous and mockworthy title.

Getting back to my original point, if we use the Kardashev Scale, which indicates how much energy a species is able to harness, humanity falls below the entry point of what I would consider advanced.  Humanity is only a 0.7 based on that objective scale, and my minimum value for what I'd consider advanced is 1.0.  Most technological species probably go extinct or devolve into a lower level of society before they ever reach Level 1 (which is what I think humanity's ultimate fate will be) and the number that I think would actually reach Level 1 is probably in the single digits, and likely the lower single digits.  I admit that the Kardashev Scale is also in some ways anthropic, but since we only have a sample size of 1, that's all we have to work with right now.  One of the reasons I like the Kardashev scale is because it makes predictions that can be verified as we move along the scale.....very similar to Isaac Asimov's psychohistory.  It's actually a nice mathematical framework for that conjecture.....and the turbulent times it predicts as we approach Level 1 were predicted by it.  I think that will only increase and will be the first of the truly Great Filters (and one that I dont believe we will be able to cross, mainly because humanity is the ultimate procrastinator and when ever more rapid responses are required to more rapid changes as we get closer to that level, a higher level of insightfulness and selflessness will be required than humanity possesses.  This is where having AI helping run our governments would be a great help- but will humanity have the selflessness to let it guide us to make decisions based purely on science, sustainability and logic (and working with nature rather than against it), and rather than the taint and corruption of money and greed?
 
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Watsisname
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22 Jun 2020 06:45

A-L-E-X wrote:
Source of the post Still every little bit counts.

If you stood in a field in front of a group of archers, and I handed you a shield and told you it will block less than 1% of their arrows, I do not believe you would be impressed by the protection. By the time your shield would catch a couple of arrows, you would be hit by hundreds.
 
A-L-E-X wrote:
Source of the post The most important factor here isn't the actual size of the moon but the proportional difference relative to the earth

The ratio between the number of asteroids that hit the Moon and the number of asteroids that hit the Earth depends mostly on their relative sizes. But what you are interested in is the Moon acting as a shield for the Earth. So what you'll want to know is the fraction of asteroids that would hit the Earth, but hit the Moon instead.

Since the Moon's gravitational sphere of influence is quite small, blocking an asteroid from hitting Earth simply depends on whether it gets directly in the way or not. Asteroids can come in from just about any direction with a nearly uniform distribution, so the fraction of asteroids the Moon prevents from hitting Earth is the fraction of the sky that the Moon covers as seen from Earth.  Today, that fraction is about 1/200,000.  For every one asteroid that the Moon prevents from hitting Earth, about 200,000 do hit Earth.  In the ancient past the Moon was closer, but even if it formed as close as the Roche limit, it still would have covered less than 1% of the sky, and hence blocked less than 1% of asteroids.

A-L-E-X wrote:
Source of the post  If we want to talk about absolute size, Jupiter was probably the best shield, especially because it actually used to be closer to the sun in the primordial solar system and migrated to its current position later on.


Jupiter is an even worse shield for Earth than the Moon. It may directly shield the Earth from about one object in a billion. The relevant quantity here is the fraction of the sky that Jupiter covers as seen by the Sun.  But even more important than Jupiter's ability to absorb asteroids or comets is its ability to gravitationally scatter them.

In fact, because of Jupiter's immense gravitational influence, it was one of the most significant causes for asteroids hitting Earth. The planetary migration in the early solar system led to Jupiter crossing an orbital resonance with Saturn, which threw the whole solar system into chaos. Asteroids were ejected from the inner asteroid belt into Earth-crossing orbits, resulting in the Late Heavy Bombardment with many of the impact craters we see on the Moon. A similar number also hit the Earth. But while the Moon's surface is very good at preserving those craters, the Earth is very good at erasing them. So we had to go to the Moon in order to learn this. :)
 
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22 Jun 2020 07:30

https://earthsky.org/space/is-it-true-t ... ects-earth
Watsisname wrote:
A-L-E-X wrote:
Source of the post Still every little bit counts.

If you stood in a field in front of a group of archers, and I handed you a shield and told you it will block less than 1% of their arrows, I do not believe you would be impressed by the protection. By the time your shield would catch a couple of arrows, you would be hit by hundreds.
 
A-L-E-X wrote:
Source of the post The most important factor here isn't the actual size of the moon but the proportional difference relative to the earth

The ratio between the number of asteroids that hit the Moon and the number of asteroids that hit the Earth depends mostly on their relative sizes. But what you are interested in is the Moon acting as a shield for the Earth. So what you'll want to know is the fraction of asteroids that would hit the Earth, but hit the Moon instead.

Since the Moon's gravitational sphere of influence is quite small, blocking an asteroid from hitting Earth simply depends on whether it gets directly in the way or not. Asteroids can come in from just about any direction with a nearly uniform distribution, so the fraction of asteroids the Moon prevents from hitting Earth is the fraction of the sky that the Moon covers as seen from Earth.  Today, that fraction is about 1/200,000.  For every one asteroid that the Moon prevents from hitting Earth, about 200,000 do hit Earth.  In the ancient past the Moon was closer, but even if it formed as close as the Roche limit, it still would have covered less than 1% of the sky, and hence blocked less than 1% of asteroids.

A-L-E-X wrote:
Source of the post  If we want to talk about absolute size, Jupiter was probably the best shield, especially because it actually used to be closer to the sun in the primordial solar system and migrated to its current position later on.


Jupiter is an even worse shield for Earth than the Moon. It may directly shield the Earth from about one object in a billion. The relevant quantity here is the fraction of the sky that Jupiter covers as seen by the Sun.  But even more important than Jupiter's ability to absorb asteroids or comets is its ability to gravitationally scatter them.

In fact, because of Jupiter's immense gravitational influence, it was one of the most significant causes for asteroids hitting Earth. The planetary migration in the early solar system led to Jupiter crossing an orbital resonance with Saturn, which threw the whole solar system into chaos. Asteroids were ejected from the inner asteroid belt into Earth-crossing orbits, resulting in the Late Heavy Bombardment with many of the impact craters we see on the Moon. A similar number also hit the Earth. But while the Moon's surface is very good at preserving those craters, the Earth is very good at erasing them. So we had to go to the Moon in order to learn this. :)

Not right now Wat- not where Jupiter is now, in the PBS series on the planets, they explained that during the early days of the solar system Jupiter was key to protecting the inner solar system because it was actually closer to the sun then it is now.  Later on it actually migrated to its current position.  Jupiter had the effect of capturing objects and changing their motion and even making many of them its satellites.
About the moon isn't there more to it than just directly shielding the earth, couldn't it also affect the path of incoming objects and change the trajectory of their motion?  In the thread you linked to, we were talking about how the relative size of the moon compared to the Earth may have impacted the development of life on earth.  The uniqueness here is that no other planet has such a relatively large natural satellite.  I admit the tidal effect is far more relevant here than in deflecting impacts, but the moon has had a role in both.

I found some things for you to read, although my connection is rather slow at this location, so more will have to wait until I get back to Long Island

https://earthsky.org/space/is-it-true-t ... ects-earth

https://www.space.com/31577-earth-life- ... pacts.html

A new simulation suggests our solar system's giant planets, Jupiter and Saturn, could have played an important role in helping life get a foothold on Earth.
(Image: © NASA/JPL)
KISSIMMEE, Fla. — Without Jupiter and Saturn orbiting out past Earth, life may not have been able to gain a foothold on our planet, new simulations suggest.

The two gas giants likely helped stabilize the solar system, protecting Earth and the other interior, rocky planets from frequent run-ins with big, fast-moving objects, researchers said.

In other words, giant planets appear to have a giant impact on giant impacts. [Moon Made by Giant Impact with Earth: New Evidence (Video)]
 
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22 Jun 2020 07:59

A-L-E-X wrote:
Source of the post About the moon isn't there more to it than just directly shielding the earth, couldn't it also affect the path of incoming objects and change the trajectory of their motion?

Not by enough to meaningfully change our result. Yes, it deflects paths, but not by very much, and a path may just as easily be deflected to hit the Earth instead of missing it. But a path must also come really close to the Moon to be deflected by much anyway, and as we just described mathematically, that is a very low probability for an approach toward Earth from any random direction.

A-L-E-X wrote:
Source of the post Not right now Wat- not where Jupiter is now, in the PBS series on the planets, they explained that during the early days of the solar system Jupiter was key to protecting the inner solar system because it was actually closer to the sun then it is now.

I've been discussing both past and present throughout...
The planets formed in different places than they are now, and they migrated. That migration led to a tremendous chaos in the early solar system, including a secondary period with a very large number of impacts. This is the Late Heavy Bombardment under the Nice Model
 
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22 Jun 2020 08:02

Watsisname wrote:
A-L-E-X wrote:
Source of the post About the moon isn't there more to it than just directly shielding the earth, couldn't it also affect the path of incoming objects and change the trajectory of their motion?

Not by enough to meaningfully change our result. Yes, it deflects paths, but only by very little, and a path may just as easily be deflected to hit the Earth instead of missing it. But a path must also come really close to the Moon to be deflected by much anyway, and that is a very low probability for an approach toward Earth from any random direction.

A-L-E-X wrote:
Source of the post Not right now Wat- not where Jupiter is now, in the PBS series on the planets, they explained that during the early days of the solar system Jupiter was key to protecting the inner solar system because it was actually closer to the sun then it is now.

I've been discussing both past and present throughout...
The planets formed in different places than they are now, and they migrated. That migration led to a tremendous chaos in the early solar system, including a secondary period with a very large number of impacts. This is the Late Heavy Bombardment under the Nice Model

Wat, this article regarding the moon's effect on our magnetic field is also very interesting:
https://www.sciencedaily.com/releases/2 ... 075118.htm
Did you have a chance yet to read the piece on Jupiter?
 
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22 Jun 2020 08:31

A-L-E-X wrote:
Source of the post Did you have a chance yet to read the piece on Jupiter?

Yes, it emphasizes how gravitational influence and scattering by gas giants works in both directions. We would not have the asteroid belt if not for Jupiter, and we wouldn't have had the Late Heavy Bombardment if not for the gas giant migration. But the simulations show Jupiter also helped decrease the time to "clear out" many of the very large planetessimals in the solar system.

This combination of "sometimes helpful, othertimes harmful" continues today. Jupiter's gravity modifies orbits of comets and generally scatters long period ones away, while it also continues to drive some asteroids out of the belt via resonances and potentially into Earth-crossing orbits.
 
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22 Jun 2020 09:43

Watsisname wrote:
A-L-E-X wrote:
Source of the post Did you have a chance yet to read the piece on Jupiter?

Yes, it emphasizes how gravitational influence and scattering by gas giants works in both directions. We would not have the asteroid belt if not for Jupiter, and we wouldn't have had the Late Heavy Bombardment if not for the gas giant migration. But the simulations show Jupiter also helped decrease the time to "clear out" many of the very large planetessimals in the solar system.

This combination of "sometimes helpful, othertimes harmful" continues today. Jupiter's gravity modifies orbits of comets and generally scatters long period ones away, while it also continues to drive some asteroids out of the belt via resonances and potentially into Earth-crossing orbits.

This is really interesting!  What do you think about certain gravitational resonances creating zones where planets are more likely to orbit (aka Titus-Bode's "law.")  Some thought this to be a coincidence but we're also seeing these patterns in exoplanetary systems too!  Over 90% of the systems we have found seem to follow this pattern.

This is also really interesting:

https://www.space.com/milky-way-teeming ... ents-32086


Looks like 53 potentially oceanic worlds for the James Webb Telescope to investigate when it launches in 2021!
 
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28 Jun 2020 08:58

Wat!  Since you're also an avid watcher of PBS as am I, have you had a look at the new Nature mini-series "Spy" (it is about small automatons that resemble the animals' natural habitat being used to explore animal behavior without disturbing them.)  The latest episode, intelligence, explored the amazingly high level of animal intelligence and human-like behavior in the wild.  Some examples:  a capuchin using stones to break open nuts, a wild orangutan picking up a saw and using it to cut wood, while holding it in place between her feet, a drongo (relative of a crow, but with red eyes), mocking the "scare cry" of the mir cat to chase them off and then stealing the food they left behind (and the mir cats figuring out what the drongo was doing so the drongo had to adjust his behavior), a crow using a stick to get termites, using different sized sticks until he got just the right one.  Elephants and other animals using medicinal herbs during during childbirth!  All amazing!

I also have a question to ask you about PBS.  For some reason, the local PBS station in Lehighton, PA where I spend a lot of time during the summer doesn't carry a lot of the nature programs I love like the NYC/Long Island/NJ PBS stations do.  If I spend a sizable amount of time in PA, can I still watch all those shows on the PBS website?

Plastic rain is the new acid rain:

https://www.wired.com/story/plastic-rai ... acid-rain/
 
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11 Jul 2020 06:32

JackDole's Universe 0.990: http://forum.spaceengine.org/viewtopic.php?f=3&t=546
JackDole's Archive: http://forum.spaceengine.org/viewtopic.php?f=3&t=419
JackDole: Mega structures ... http://old.spaceengine.org/forum/17-3252-1 (Old forum)
 
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29 Jul 2020 03:32

An asteroid the size of a car just zipped by Earth in close flyby


19 hours ago

A car-sized asteroid discovered over the weekend made a close flyby of Earth today (July 28), passing our planet at a range that rivals the orbits of some high-flying satellites.

The asteroid 2020 OY4, which was first detected on Sunday (July 26), made its closest approach today at 1:31 a.m. EDT (0531 GMT) when it zipped by Earth at a speed of about 27,700 mph (44,600 km/h), according to the European Space Agency.

The asteroid is just under 10 feet (3 meters) wide and posed no impact risk to Earth, but did approach the flight paths of geosynchronous satellites. 

"A tiny, 3 meter asteroid called 2020 OY4 skimmed past Earth just a few hours ago, passing within the orbit of satellites in the geostationary ring," ESA officials wrote in a Twitter update.

https://www.space.com/car-size-asteroid ... flyby.html
Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what makes the universe exist. Be curious.

Stephen Hawking
 
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29 Jul 2020 13:14

GloucesterLad wrote:
Source of the post An asteroid the size of a car just zipped by Earth in close flyby

Here you can find a script for this object: viewtopic.php?f=3&t=546&start=60#p34223
JackDole's Universe 0.990: http://forum.spaceengine.org/viewtopic.php?f=3&t=546
JackDole's Archive: http://forum.spaceengine.org/viewtopic.php?f=3&t=419
JackDole: Mega structures ... http://old.spaceengine.org/forum/17-3252-1 (Old forum)
 
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30 Jul 2020 14:02

I would like to see a script that programs the 7 month journey of the new Perseverance rover to Mars and maybe a simulation of it and if the new solar powered helicopter Ingenuity on the planet :-)
 
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05 Aug 2020 17:01

https://www.quantamagazine.org/big-boun ... /#comments

simulations of the Big Bounce may explain structures we see today

https://www.quantamagazine.org/physicis ... /#comments

https://www.nature.com/news/scientific-method-defend-the-integrity-of-physics-1.16535

this is fascinating, although I disagree with them- these theories are testable.  For example we could infer the existence of a multiverse from how the gravitation of another universe affects our own (dark flow).
 
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01 Sep 2020 04:55

The last news says that on the 1st of September (today!) a multi-storey building size asteroid will fly near the Earth. The approach will be at 7 pm (GMT+3). An asteroid will approach the planet at a distance of about 120 thousand kilometers. Just for comparison, the distance from the Moon to the Earth is 384,4 thousand kilometers.  
 
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Watsisname
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01 Sep 2020 20:14

John Done wrote:
Source of the post An asteroid will approach the planet at a distance of about 120 thousand kilometers. Just for comparison, the distance from the Moon to the Earth is 384,4 thousand kilometers.  

In those terms, that actually doesn't sound very close at all. The Moon is farther away than most people realize, especially when asked to draw the Earth-Moon system to scale. Asteroids pass within the orbit of the Moon rather often, though to be that close and also of that size is somewhat rare.

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