Starship Asterisk*

neufer wrote: ↑Sun Oct 21, 2018 4:26 pm

https://en.wikipedia.org/wiki/Musica_universalis wrote: https://www.youtube.com/watch?v=1EFZuzgcIzY

Confused wrote: ↑Sun Oct 21, 2018 4:37 am

MarkBour wrote: ↑Mon Dec 11, 2017 10:44 pm
I can recall being surprised that instrumental music was included on a JPL or a NASA video once or twice, but I think it is pretty common to do so now, particularly when one is just "looking at landscape", so I no longer think about it.

Yes it is becoming so common to always have music playing that some people are going to think that there must be something wrong if there is no music. People are playing music automatically, without thinking, just because it is the way to do things; at least people are being told that implicitly. Stores and restaurants and many other businesses think that music is a requirement.

I think it is reasonable and probably necessary for some people to make it clear that it is not really necessary to add music.

https://en.wikipedia.org/wiki/Musica_universalis wrote:

Click to play embedded YouTube video.

<<Musica universalis (literally universal music), also called Music of the spheres or Harmony of the Spheres, is an ancient philosophical concept that regards proportions in the movements of celestial bodies—the Sun, Moon, and planets—as a form of musica (the Medieval Latin term for music). This "music" is not usually thought to be literally audible, but a harmonic, mathematical or religious concept. The idea continued to appeal to thinkers about music until the end of the Renaissance, influencing scholars of many kinds, including humanists. Further scientific exploration has determined specific proportions in some orbital motion, described as orbital resonance.

In a theory known as the Harmony of the Spheres, Pythagoras proposed that the Sun, Moon and planets all emit their own unique hum based on their orbital revolution, and that the quality of life on Earth reflects the tenor of celestial sounds which are physically imperceptible to the human ear. Aristotle criticised the notion that celestial bodies make a sound in moving in the context of his own cosmological model.

According to Max Heindel's Rosicrucian writings, the heavenly "music of the spheres" is heard in the Region of Concrete Thought, the lower region of the mental plane, which is an ocean of harmony.>>

MarkBour wrote: ↑Mon Dec 11, 2017 10:44 pm I can recall being surprised that instrumental music was included on a JPL or a NASA video once or twice, but I think it is pretty common to do so now, particularly when one is just "looking at landscape", so I no longer think about it.

neufer wrote: ... However, this scenario total ignores the tremendous frictional forces
and thermal heating of the mercurial meteor.

Chris Peterson wrote:

BDanielMayfield wrote:

neufer wrote: ... At such a time the sub-Solar point of a then tidally locked Mercury would only see the Sun and would, indeed, have to share its 3600 K temperature.
... However, this scenario total ignores the tremendous frictional forces and thermal heating of the mercurial meteor.

... tidally locked Mercury's magma ocean ...
Bruce

It's certainly not an unreasonable assumption. Just as long as we don't forget that it is still an assumption until somebody provides a more rigorous analysis. Sometimes we get caught off guard by things. I know how surprised I was when I first came to understand that planets could orbit, unmelted, in stable orbits, for a long time inside a red giant. That was entirely counter to my intuition at the time.

BDanielMayfield wrote:but still I don't think that this assumption:

MarkBour wrote:I suppose Mercury would become an "ocean planet" at the last.

is all that far fetched.

neufer wrote:

BDanielMayfield wrote:
I wonder where the point will be on the Sun's evolutionary tract where Mercury is just skimming the photosphere?

At that point the surface of the poor planet would have to have reached the same temp as the photosphere, wouldn't it?

If Mercury were somehow to retain its (periastron) distance of 46 million kilometers = 66 Solar radii
the Sun would cool have to around 3600 K with a luminosity of ~660 [= 66² x (3600 K / 5772 K)⁴ ].

At such a time the sub-Solar point of a then tidally locked Mercury
would only see the Sun and would, indeed, have to share its 3600 K temperature.

However, this scenario total ignores the tremendous frictional forces
and thermal heating of the mercurial meteor.

Chris Peterson wrote:

BDanielMayfield wrote:I wonder where the point will be on the Sun's evolutionary tract where Mercury is just skimming the photosphere? At that point the surface of the poor planet would have to have reached the same temp as the photosphere, wouldn't it?

Again, not necessarily. The ISS flies through the upper atmosphere of Earth, which is at a temperature of 1000°C or more. Does the surface of the ISS reach that temperature? Luckily not! What Mercury is going to encounter as the Sun swells to a red giant is a tenuous atmosphere and a complicated radiative and convective environment. Not something easily analyzed, I think, so I'd be cautious making any assumptions.

MarkBour wrote:I suppose Mercury would become an "ocean planet" at the last.

BDanielMayfield wrote:
I wonder where the point will be on the Sun's evolutionary tract where Mercury is just skimming the photosphere?

At that point the surface of the poor planet would have to have reached the same temp as the photosphere, wouldn't it?

BDanielMayfield wrote:I wonder where the point will be on the Sun's evolutionary tract where Mercury is just skimming the photosphere? At that point the surface of the poor planet would have to have reached the same temp as the photosphere, wouldn't it?

neufer wrote:

BDanielMayfield wrote:Mercury is toast for sure. But with its elliptical orbit it should put on an interesting show for a relatively short while as it skims the Sun's surface at periastron. Perhaps it will briefly "plunge" beneath the Sun's photosphere several times only to re-emerge on the outward part of its orbit. But it's doomed, as its orbit decays and the Sun swells.

By my calculations when the Sun's corona reaches out to Mercury
it will start to intercept about 50 x 10¹⁶ kg of material per 88 day orbit.

Since the mass of Mercury is only 33,000,000 x 10¹⁶ kg
it should begin to rapidly dissipate kinetic energy over a period of ~660,000 orbits or ~160,000 years.

Note, however, that Mercury will transition into a circular orbit long before it reaches the chromosphere or photosphere.

neufer wrote:

[b][color=#0000FF]Sun-like stars have a degenerate core on the red giant branch and ascend to the tip before starting core helium fusion with a flash.[/color][/b]

---

Chris Peterson wrote:

BDanielMayfield wrote: Mercury will come to have a liquid metallic surface, and thus its name will be even more fitting near its end.

It may not. The outer part of a red giant is remarkably tenuous and cool. That combination means that planets may orbit inside the expanded Sun for thousands of years without melting. Of course, it may be a lot rougher ride for Mercury than for Earth or Mars.

The sub-solar point on Mercury is already 700 K
... about half the lava temperature of ~1400 K

The Sun only has to become about 16 times as luminous to turn the sub-solar point on Mercury to ~1400 K lava.

Chris Peterson wrote:

BDanielMayfield wrote:

MarkBour wrote:
As the Sun swells, I wonder how the solar wind density will change, and the extent of the corona. With a temperature of that environment being around 1 million degrees, I suppose Mercury would become an "ocean planet" at the last.

Mercury will come to have a liquid metallic surface, and thus its name will be even more fitting near its end.

It may not. The outer part of a red giant is remarkably tenuous and cool. That combination means that planets may orbit inside the expanded Sun for thousands of years without melting. Of course, it may be a lot rougher ride for Mercury than for Earth or Mars.

BDanielMayfield wrote:

MarkBour wrote:

BDanielMayfield wrote: Yeah, Mercury is toast for sure. But with its elliptical orbit it should put on an interesting show for a relatively short while as it skims the Sun's surface at periastron. Perhaps it will briefly "plunge" beneath the Sun's photosphere several times only to re-emerge on the outward part of its orbit. But it's doomed, as its orbit decays and the Sun swells.
Bruce

Interesting speculations. As the Sun swells, I wonder how the solar wind density will change, and the extent of the corona. With a temperature of that environment being around 1 million degrees, I suppose Mercury would become an "ocean planet" at the last. (Ha! A good question for the IAU then would be at which point it would cease to meet the definition of a planet :-))

Mercury will come to have a liquid metallic surface, and thus its name will be even more fitting near its end.

BDanielMayfield wrote:

Chris Peterson wrote:

barobins@telusplanet.net wrote:
Will Mercury ever plunge into the Sun? What would happen to Earth should that happen? Would it be thrown out of it's orbit??

No. Eventually the Sun will expand outward so far that Mercury will be inside it, at which point drag will likely result in it spiraling down into the Sun's interior and eventually being vaporized. This will have no effect on any of the other planets (although the Earth will share a similar fate somewhat later).

Yeah, Mercury is toast for sure. But with its elliptical orbit it should put on an interesting show for a relatively short while as it skims the Sun's surface at periastron. Perhaps it will briefly "plunge" beneath the Sun's photosphere several times only to re-emerge on the outward part of its orbit. But it's doomed, as its orbit decays and the Sun swells.

Snooky wrote:It appears that this was put together from a whole year's worth of observations. The planet rotates about one and a quarter times or a little more during the course of the video. Very nice!

MarkBour wrote:

BDanielMayfield wrote:

Chris Peterson wrote: No. Eventually the Sun will expand outward so far that Mercury will be inside it, at which point drag will likely result in it spiraling down into the Sun's interior and eventually being vaporized. This will have no effect on any of the other planets (although the Earth will share a similar fate somewhat later).

Yeah, Mercury is toast for sure. But with its elliptical orbit it should put on an interesting show for a relatively short while as it skims the Sun's surface at periastron. Perhaps it will briefly "plunge" beneath the Sun's photosphere several times only to re-emerge on the outward part of its orbit. But it's doomed, as its orbit decays and the Sun swells.
Bruce

Interesting speculations. As the Sun swells, I wonder how the solar wind density will change, and the extent of the corona. With a temperature of that environment being around 1 million degrees, I suppose Mercury would become an "ocean planet" at the last. (Ha! A good question for the IAU then would be at which point it would cease to meet the definition of a planet )

BDanielMayfield wrote:

Chris Peterson wrote:

barobins@telusplanet.net wrote:Will Mercury ever plunge into the Sun? What would happen to Earth should that happen? Would it be thrown out of it's orbit??

No. Eventually the Sun will expand outward so far that Mercury will be inside it, at which point drag will likely result in it spiraling down into the Sun's interior and eventually being vaporized. This will have no effect on any of the other planets (although the Earth will share a similar fate somewhat later).

Yeah, Mercury is toast for sure. But with its elliptical orbit it should put on an interesting show for a relatively short while as it skims the Sun's surface at periastron. Perhaps it will briefly "plunge" beneath the Sun's photosphere several times only to re-emerge on the outward part of its orbit. But it's doomed, as its orbit decays and the Sun swells.
Bruce

Chris Peterson wrote:

barobins@telusplanet.net wrote:Will Mercury ever plunge into the Sun? What would happen to Earth should that happen? Would it be thrown out of it's orbit??

No. Eventually the Sun will expand outward so far that Mercury will be inside it, at which point drag will likely result in it spiraling down into the Sun's interior and eventually being vaporized. This will have no effect on any of the other planets (although the Earth will share a similar fate somewhat later).

MarkBour wrote:By the way, when I was a kid, they told me that Mercury was tidally locked to the Sun, 1 rotation per revolution (synchronous rotation). Today I learned that instead, Mercury is much more interesting! It has been locked into a "Rotation–orbit resonance" of 3:2 (3 rotations per 2 revolutions). And this results in:

• The planet does have day and night everywhere on the surface other than the poles;
• The day (sunrise to sunrise, not sidereal) is two times as long as its year;
• The apparent movement of the Sun across the sky is very slow at perihelion, probably almost stops, but not quite;
• The earlier mistaken information that Mercury was tidally locked is somewhat forgivable. It is *hard* to observe the surface of Mercury from Earth. And there are only certain times and positions where you can get a relatively good look, and those times were in resonance of the motions of Earth and Mercury in such a way that observers were fooled into missing the complexity of Mercury's motion. But at least some people knew better even when I was a child. But pre-internet, it was nothing to be learning from materials that were a decade or more old.

bystander wrote:

Confused wrote: So is it Mercury or is it music?

APOD wrote:Music: Open Sea Morning by Puddle of Infinity

JohnD wrote:It gave Mercury a strange appearance, as if it was transparent over a deeper solid surface, like dust and leaves floating on a puddle.
Anyone else have that sensation?
John

• The planet does have day and night everywhere on the surface other than the poles;
• The day (sunrise to sunrise, not sidereal) is two times as long as its year;
• The apparent movement of the Sun across the sky is very slow at perihelion, probably almost stops, but not quite;
• The earlier mistaken information that Mercury was tidally locked is somewhat forgivable. It is *hard* to observe the surface of Mercury from Earth. And there are only certain times and positions where you can get a relatively good look, and those times were in resonance of the motions of Earth and Mercury in such a way that observers were fooled into missing the complexity of Mercury's motion. But at least some people knew better even when I was a child. But pre-internet, it was nothing to be learning from materials that were a decade or more old.

Confused wrote: So is it Mercury or is it music?

APOD wrote:Music: Open Sea Morning by Puddle of Infinity

rstevenson wrote:I am also confused -- by your excessive reaction. I hear quiet contemplative music which I find quite enjoyable. Maybe you should think about adjusting your computer's sound output.

JohnD wrote:Glad it's not just me.
Artefact of the animation??