APOD: The Dance of Venus and Earth (2020 Jun 03)

Comments and questions about the APOD on the main view screen.
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neufer
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APOD: The Dance of Venus and Earth (2020 Jun 03)

Post by neufer » Thu Dec 23, 2021 4:31 pm

Chris Peterson wrote: Thu Jun 04, 2020 4:38 pm
Jerome68 wrote: Thu Jun 04, 2020 4:30 pm
Chris Peterson wrote: Thu Jun 04, 2020 4:01 pm
The near orbital resonance is just a coincidence. But that same near resonance might play a role in the orbital-rotational relationship that seems to keep the same place on the surface rotating into the same position at each inferior conjunction... meaning the latter might not be a coincidence at all, but something that follows physically as a consequence of a coincidence.
I normally will agree with you, but it also shows the history of science that a coincidence is hiding some big discover, wouldn't be this the case? (I don't pretend to say I know it, but, why not? also, the moon is showing us the same face, why not a way to interact we don't know would explain it?). Coincidences in science are very rarely (in my opinion) :)
Because we have a very, very good understanding of the underlying science involved in orbital dynamics. There are many examples of coincidental near orbital resonances throughout the Solar System. They are expected to occur based on simple statistics, and the observed probabilities are consistent with that. There is no reason at all to believe that some unknown factor is at play. The uncertainty with respect to whether there is a physical mechanism creating the apparent orbital-rotational synchronization between Earth and Venus exists because of a lack of complete information (this involves complex elements such as Venusian atmospheric dynamics). That lack of information doesn't exist when it comes to the actual orbits of the two planets.
We have a very, very poor understanding of all the chaos involved in orbital dynamics over the life span of the solar system.

There may be many near orbital resonances that are, in fact, fossil remnants of earlier solar system dynamics.
https://en.wikipedia.org/wiki/Jumping-Jupiter_scenario wrote:
Click to play embedded YouTube video.

<<The jumping-Jupiter scenario specifies an evolution of giant-planet migration described by the Nice model, in which an ice giant (Uranus, Neptune, or an additional Neptune-mass planet) is scattered inward by Saturn and outward by Jupiter, causing their semi-major axes to jump, quickly separating their orbits. During this migration secular resonances swept through the inner Solar System exciting the orbits of the terrestrial planets and the asteroids, leaving the planets' orbits too eccentric, and the asteroid belt with too many high-inclination objects. The jumps in the semi-major axes of Jupiter and Saturn described in the jumping-Jupiter scenario can allow these resonances to quickly cross the inner Solar System without altering orbits excessively, although the terrestrial planets remain sensitive to its passage.

A giant-planet migration in which the ratio of the periods of Jupiter and Saturn quickly cross from below 2.1 to greater than 2.3 can leave the terrestrial planets with orbits similar to their current orbits. The eccentricities and inclinations of a group of planets can be represented by the angular momentum deficit (AMD), a measure of the differences of their orbits from circular coplanar orbits. The orbit of Mars is largely unchanged in these simulations indicating that its initial orbit must have been more eccentric and inclined than those of the other planets.

The jumping-Jupiter model can reproduce the eccentricity and inclination of Mercury's orbit. Mercury's eccentricity is excited when it crosses a secular resonance with Jupiter. When relativistic effects are included, Mercury's precession rate is faster, which reduces the impact of this resonance crossing, and results in a smaller eccentricity similar to its current value. Mercury's inclination may be the result of it or Venus crossing a secular resonance with Uranus.>>
Art Neuendorffer

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Chris Peterson
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APOD: The Dance of Venus and Earth (2020 Jun 03)

Post by Chris Peterson » Thu Dec 23, 2021 5:05 pm

neufer wrote: Thu Dec 23, 2021 4:31 pm
Chris Peterson wrote: Thu Jun 04, 2020 4:38 pm
Jerome68 wrote: Thu Jun 04, 2020 4:30 pm

I normally will agree with you, but it also shows the history of science that a coincidence is hiding some big discover, wouldn't be this the case? (I don't pretend to say I know it, but, why not? also, the moon is showing us the same face, why not a way to interact we don't know would explain it?). Coincidences in science are very rarely (in my opinion) :)
Because we have a very, very good understanding of the underlying science involved in orbital dynamics. There are many examples of coincidental near orbital resonances throughout the Solar System. They are expected to occur based on simple statistics, and the observed probabilities are consistent with that. There is no reason at all to believe that some unknown factor is at play. The uncertainty with respect to whether there is a physical mechanism creating the apparent orbital-rotational synchronization between Earth and Venus exists because of a lack of complete information (this involves complex elements such as Venusian atmospheric dynamics). That lack of information doesn't exist when it comes to the actual orbits of the two planets.
We have a very, very poor understanding of all the chaos involved in orbital dynamics over the life span of the solar system.

There may be many near orbital resonances that are, in fact, fossil remnants of earlier solar system dynamics.
That doesn't change the fact that our understanding of the dynamics is near perfect. It simply reflects a lack of access to all the inputs that formed our system.
Chris

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Cloudbait Observatory
http://www.cloudbait.com

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neufer
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APOD: The Dance of Venus and Earth (2020 Jun 03)

Post by neufer » Thu Dec 23, 2021 8:39 pm

Chris Peterson wrote: Thu Dec 23, 2021 5:05 pm
neufer wrote: Thu Dec 23, 2021 4:31 pm
Chris Peterson wrote: Thu Jun 04, 2020 4:38 pm
Because we have a very, very good understanding of the underlying science involved in orbital dynamics. There are many examples of coincidental near orbital resonances throughout the Solar System. They are expected to occur based on simple statistics, and the observed probabilities are consistent with that. There is no reason at all to believe that some unknown factor is at play. The uncertainty with respect to whether there is a physical mechanism creating the apparent orbital-rotational synchronization between Earth and Venus exists because of a lack of complete information (this involves complex elements such as Venusian atmospheric dynamics). That lack of information doesn't exist when it comes to the actual orbits of the two planets.
We have a very, very poor understanding of all the chaos involved in orbital dynamics over the life span of the solar system.

There may be many near orbital resonances that are, in fact, fossil remnants of earlier solar system dynamics.
That doesn't change the fact that our understanding of the dynamics is near perfect.
It simply reflects a lack of access to all the inputs that formed our system.
Computers (and our imaginations) struggle most with time reversed dynamics:
Click to play embedded YouTube video.
Art Neuendorffer

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Chris Peterson
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Posts: 16606
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

APOD: The Dance of Venus and Earth (2020 Jun 03)

Post by Chris Peterson » Thu Dec 23, 2021 10:48 pm

neufer wrote: Thu Dec 23, 2021 8:39 pm
Chris Peterson wrote: Thu Dec 23, 2021 5:05 pm
neufer wrote: Thu Dec 23, 2021 4:31 pm
We have a very, very poor understanding of all the chaos involved in orbital dynamics over the life span of the solar system.

There may be many near orbital resonances that are, in fact, fossil remnants of earlier solar system dynamics.
That doesn't change the fact that our understanding of the dynamics is near perfect.
It simply reflects a lack of access to all the inputs that formed our system.
Computers (and our imaginations) struggle most with time reversed dynamics:
There is no closed solution to the previous state of the Solar System. So all we can do is make educated guesses and propagate them forward to see how close they match what we observe today.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com