APOD: Tycho and Clavius (2021 Aug 05)

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APOD: Tycho and Clavius (2021 Aug 05)

Post by APOD Robot » Thu Aug 05, 2021 4:05 am

Image Tycho and Clavius

Explanation: South is up in this detailed telescopic view across the Moon's rugged southern highlands. Captured on July 20, the lunar landscape features the Moon's young and old, the large craters Tycho and Clavius. About 100 million years young, Tycho is the sharp-walled 85 kilometer diameter crater near center, its 2 kilometer tall central peak in bright sunlight and dark shadow. Debris ejected during the impact that created Tycho still make it the stand out lunar crater when the Moon is near full, producing a highly visible radiating system of light streaks, bright rays that extend across much of the lunar near side. In fact, some of the material collected at the Apollo 17 landing site, about 2,000 kilometers away, likely originated from the Tycho impact. One of the oldest and largest craters on the Moon's near side, 225 kilometer diameter Clavius is due south (above) of Tycho. Clavius crater's own ray system resulting from its original impact event would have faded long ago. The old crater's worn walls and smooth floor are now overlayed by smaller craters from impacts that occurred after Clavius was formed. Observations by the Stratospheric Observatory for Infrared Astronomy (SOFIA) published in 2020 found water at Clavius. Of course both young Tycho and old Clavius craters are lunar locations in the science fiction epic 2001: A Space Odyssey.

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by Ann » Thu Aug 05, 2021 4:22 am

Luna-Tycho-Clavius-high1024[1].jpg

Tycho and Clavius?

Hmm, I think I'd rather read about Tycho and Clavius.

Click to play embedded YouTube video.

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by RocketRon » Thu Aug 05, 2021 6:32 am

Anyone/anything living there would have had a tough time selecting a spot that didn't take a beating over the eons !?

"The old crater's worn walls and smooth floor are now overlayed by smaller craters from impacts that occurred after Clavius was formed.".

Worn from what though ?
There is no atmosphere nor rain there to "weather" things, so what is doing the eroding/wearing/smoothing ??
Apart from a good dusting and beating from space rocks impacting - is that all that is doing the wearing down ?

Thats a rough looking surface when seen close up, and hostile in the extreme.
Anyone thinking of setting up camp there had better be prepared. Well prepared ...

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by De58te » Thu Aug 05, 2021 10:55 am

RocketRon wrote:
Thu Aug 05, 2021 6:32 am
Anyone/anything living there would have had a tough time selecting a spot that didn't take a beating over the eons !?

"The old crater's worn walls and smooth floor are now overlayed by smaller craters from impacts that occurred after Clavius was formed.".

Worn from what though ?
There is no atmosphere nor rain there to "weather" things, so what is doing the eroding/wearing/smoothing ??
Apart from a good dusting and beating from space rocks impacting - is that all that is doing the wearing down ?

Thats a rough looking surface when seen close up, and hostile in the extreme.
Anyone thinking of setting up camp there had better be prepared. Well prepared ...
The Moon may not have weathering today, but it was a different story 4 billion years ago. The Moon was half the distance from the Earth then. Today the Moon's tidal forces can raise oceans a few feet. Imagine the Earth's tidal force on the Moon when it was much closer. Moonquakes galore could have created rock slides. Moon volcanoes erupted. There are thousands of crater impacts. Each one blew gravel and dust up over the surface. Moon dust is not smooth as on Earth but has little jagged edges. When the dust fell back, it took a small chunk out of the crater wall, but only once, until the next impact. And it is believed that the Moon 4 billion years ago did have an atmosphere similar to Mars. That caused wind erosion. There is also temperature difference of 100s degrees between the shadows in the craters and the sunny side. Heat expansion could cause loose particle slides. The ancient atmosphere could be responsible for eroding the old large craters like Clavius, but the atmosphere was already gone when younger Tycho hit.

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by orin stepanek » Thu Aug 05, 2021 12:02 pm

Luna-Tycho-Clavius-high.jpg
I take it these are the two craters described in today's APOD! Hope I
labeled them right! :roll:
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by neufer » Thu Aug 05, 2021 1:36 pm

https://en.wikipedia.org/wiki/Christopher_Clavius wrote:
<<Christopher Clavius (25 March 1538 – 6 February 1612) was a Jesuit German mathematician and astronomer who was a member of the Vatican commission that accepted the proposed calendar invented by Aloysius Lilius, that is known as Gregorian calendar. Clavius would later write defences and an explanation of the reformed calendar, including an emphatic acknowledgement of Lilius' work. In his last years he was probably the most respected astronomer in Europe and his textbooks were used for astronomical education for over fifty years in and even out of Europe.

Within the Jesuit order, Clavius was almost single-handedly responsible for the adoption of a rigorous mathematics curriculum in an age where mathematics was often ridiculed by philosophers as well as fellow Jesuits like Benito Pereira. He used the decimal point in the goniometric tables of his astrolabium in 1593 and he was one of the first who used it in this way in the West. In logic, Clavius' Law (inferring of the truth of a proposition from the inconsistency of its negation) is named after him.

As an astronomer Clavius held strictly to the geocentric model of the solar system, in which all the heavens rotate about the Earth. Though he opposed the heliocentric model of Copernicus, he recognized problems with the Ptolemaic model. He was treated with great respect by Galileo, who visited him in 1611 and discussed the new observations being made with the telescope; Clavius had by that time accepted the new discoveries as genuine, though he retained doubts about the reality of the mountains on the Moon. Later, a large crater on the Moon was named in his honor.>>
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by Chris Peterson » Thu Aug 05, 2021 2:37 pm

De58te wrote:
Thu Aug 05, 2021 10:55 am
RocketRon wrote:
Thu Aug 05, 2021 6:32 am
Anyone/anything living there would have had a tough time selecting a spot that didn't take a beating over the eons !?

"The old crater's worn walls and smooth floor are now overlayed by smaller craters from impacts that occurred after Clavius was formed.".

Worn from what though ?
There is no atmosphere nor rain there to "weather" things, so what is doing the eroding/wearing/smoothing ??
Apart from a good dusting and beating from space rocks impacting - is that all that is doing the wearing down ?

Thats a rough looking surface when seen close up, and hostile in the extreme.
Anyone thinking of setting up camp there had better be prepared. Well prepared ...
The Moon may not have weathering today, but it was a different story 4 billion years ago. The Moon was half the distance from the Earth then. Today the Moon's tidal forces can raise oceans a few feet. Imagine the Earth's tidal force on the Moon when it was much closer. Moonquakes galore could have created rock slides. Moon volcanoes erupted. There are thousands of crater impacts. Each one blew gravel and dust up over the surface. Moon dust is not smooth as on Earth but has little jagged edges. When the dust fell back, it took a small chunk out of the crater wall, but only once, until the next impact. And it is believed that the Moon 4 billion years ago did have an atmosphere similar to Mars. That caused wind erosion. There is also temperature difference of 100s degrees between the shadows in the craters and the sunny side. Heat expansion could cause loose particle slides. The ancient atmosphere could be responsible for eroding the old large craters like Clavius, but the atmosphere was already gone when younger Tycho hit.
The Moon continues to experience weathering, in the form of a continuous bombardment of radiation, charged particles, dust, gravel, and occasional larger bodies, and moonquakes (as well as the thermal weathering you refer to).
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Post by neufer » Thu Aug 05, 2021 3:54 pm

Chris Peterson wrote:
Thu Aug 05, 2021 2:37 pm
De58te wrote:
Thu Aug 05, 2021 10:55 am

The Moon may not have weathering today, but it was a different story 4 billion years ago. The Moon was half the distance from the Earth then. Today the Moon's tidal forces can raise oceans a few feet. Imagine the Earth's tidal force on the Moon when it was much closer. Moonquakes galore could have created rock slides. Moon volcanoes erupted. There are thousands of crater impacts. Each one blew gravel and dust up over the surface. Moon dust is not smooth as on Earth but has little jagged edges. When the dust fell back, it took a small chunk out of the crater wall, but only once, until the next impact. And it is believed that the Moon 4 billion years ago did have an atmosphere similar to Mars. That caused wind erosion. There is also temperature difference of 100s degrees between the shadows in the craters and the sunny side. Heat expansion could cause loose particle slides. The ancient atmosphere could be responsible for eroding the old large craters like Clavius, but the atmosphere was already gone when younger Tycho hit.
The Moon continues to experience weathering, in the form of a continuous bombardment of radiation, charged particles, dust, gravel, and occasional larger bodies, and moonquakes (as well as the thermal weathering you refer to).
  • Dust, gravel, and occasional larger bodies :?:

    Whatever happened to micrometeoroids, meteoroids, and occasional meteors?
https://en.wikipedia.org/wiki/Tektite wrote:
<<Tektites (from Greek τηκτός tēktós, "molten") are gravel-sized bodies composed of black, green, brown, or gray natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz Eduard Suess (1867–1941), son of Eduard Suess. They generally range in size from millimeters to centimeters. Millimeter-scale tektites are known as microtektites. Tektites are characterized by:
  • a fairly homogeneous composition
    an extremely low content of water and other volatiles
    an abundance of lechatelierite
    a general lack of microscopic crystals known as microlites and chemical relation to the local bedrock or local sediments
    their distribution within geographically extensive strewn fields
Though the meteorite impact theory of tektite formation is widely accepted, there has been considerable controversy about their origin in the past. As early as 1897, the Dutch geologist Rogier Diederik Marius Verbeek (1845–1926) suggested an extraterrestrial origin for tektites: he proposed that they fell to Earth from the Moon. Verbeek's proposal of an extraterrestrial origin for tektites was soon seconded by the German geologist Franz E. Suess. Subsequently, it was argued that tektites consist of material that was ejected from the Moon by major hydrogen-driven lunar volcanic eruptions and then drifted through space to later fall to Earth as tektites.

The major proponents of the lunar origin of tektites include NASA scientist John A. O'Keefe, NASA aerodynamicist Dean R. Chapman, meteorite and tektite collector Darryl Futrell, and long-time tektite researcher Hal Povenmire. From the 1950s to the 1990s, O'Keefe argued for the lunar origin of tektites based upon their chemical, i.e. rare-earth, isotopic, and bulk, composition and physical properties. Chapman used complex orbital computer models and extensive wind tunnel tests to argue that the so-called Australasian tektites originated from the Rosse ejecta ray of the large crater Tycho on the Moon's near side. O'Keefe, Povenmire, and Futrell claimed on the basis of behavior of glass melts that the homogenization, which is called "fining", of silica melts that characterize tektites could not be explained by the terrestrial-impact theory. They also argued that the terrestrial-impact theory could not explain the vesicles and extremely low water and other volatile content of tektites. Futrell also reported the presence of microscopic internal features within tektites, which argued for a volcanic origin.

At one time, theories advocating the lunar origin of tektites enjoyed considerable support as part of a spirited controversy about the origin of tektites that occurred during the 1960s. Starting with the publication of research concerning lunar samples returned from the Moon, the consensus of Earth and planetary scientists shifted in favor of theories advocating a terrestrial impact versus lunar volcanic origin. For example, one problem with the lunar origin theory is that the arguments for it that are based upon the behavior of glass melts use data from pressures and temperatures that are vastly uncharacteristic of and unrelated to the extreme conditions of hypervelocity impacts. In addition, various studies have shown that hypervelocity impacts are likely quite capable of producing low volatile melts with extremely low water content. The consensus of Earth and planetary scientists regards the chemical, i.e. rare-earth, isotopic, and bulk composition evidence as decisively demonstrating that tektites are derived from terrestrial crustal rock, i.e. sedimentary rocks, that are unlike any known lunar crust.>>
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Re: Every time it rains, it rains, gravel from heaven.

Post by Chris Peterson » Thu Aug 05, 2021 4:02 pm

neufer wrote:
Thu Aug 05, 2021 3:54 pm
Chris Peterson wrote:
Thu Aug 05, 2021 2:37 pm
De58te wrote:
Thu Aug 05, 2021 10:55 am

The Moon may not have weathering today, but it was a different story 4 billion years ago. The Moon was half the distance from the Earth then. Today the Moon's tidal forces can raise oceans a few feet. Imagine the Earth's tidal force on the Moon when it was much closer. Moonquakes galore could have created rock slides. Moon volcanoes erupted. There are thousands of crater impacts. Each one blew gravel and dust up over the surface. Moon dust is not smooth as on Earth but has little jagged edges. When the dust fell back, it took a small chunk out of the crater wall, but only once, until the next impact. And it is believed that the Moon 4 billion years ago did have an atmosphere similar to Mars. That caused wind erosion. There is also temperature difference of 100s degrees between the shadows in the craters and the sunny side. Heat expansion could cause loose particle slides. The ancient atmosphere could be responsible for eroding the old large craters like Clavius, but the atmosphere was already gone when younger Tycho hit.
The Moon continues to experience weathering, in the form of a continuous bombardment of radiation, charged particles, dust, gravel, and occasional larger bodies, and moonquakes (as well as the thermal weathering you refer to).
  • Dust, gravel, and occasional larger bodies :?:

    Whatever happened to micrometeoroids, meteoroids, and occasional meteors?
As there are no meteors on the Moon, we generally don't use the term "meteoroid" for pre-impact particles. "Dust" is the most common term for the tiny debris that peppers atmosphereless bodies. For larger collisions, "impactors" or "asteroids" are common terms.
Chris

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by VictorBorun » Thu Aug 05, 2021 4:42 pm


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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by MarkBour » Thu Aug 05, 2021 4:52 pm

orin stepanek wrote:
Thu Aug 05, 2021 12:02 pm
Luna-Tycho-Clavius-high.jpg

I take it these are the two craters described in today's APOD! Hope I
labeled them right! :roll:
Nailed it, Orin.
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by MarkBour » Thu Aug 05, 2021 5:17 pm

Very nice image, Eduardo Schaberger! Taken with a camera mounted to a refractor? I'm curious about the gear used for this image.

Low in the picture (to the north of Tycho crater) I like this little bulls-eye crater:
Capture.png
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by neufer » Thu Aug 05, 2021 6:49 pm

Click to play embedded YouTube video.
Click to play embedded YouTube video.
VictorBorun wrote:
Thu Aug 05, 2021 4:42 pm


a curving chain of craters that begins with Rutherfurd in the south then arcs across the floor in a counterclockwise direction forming a sequence of ever diminishing diameters. From largest to smallest, these craters are designated Clavius D, C, N, J, and JA.

This chain looks regular, does not it?

Like there was a hitting asteroid that at first merely touched the surface, but gradually hit after hit made ever more steep jumps and hits.

Besides it was tumbling and its spin made a curve path of its hits.
And yet the rim of Clavius is still there :!:
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by neufer » Thu Aug 05, 2021 7:14 pm

https://en.wikipedia.org/wiki/The_Dam_Busters_(film) wrote:
Click to play embedded YouTube video.
Click to play embedded YouTube video.
<<The Dam Busters is a 1955 British epic war film starring Richard Todd and Michael Redgrave. The attack on the Death Star in the climax of the film Star Wars is a deliberate and acknowledged homage to the climactic sequence of The Dam Busters. In the former film, rebel pilots have to fly through a trench while evading enemy fire and fire a proton torpedo at a precise distance from the target to destroy the entire base with a single explosion; if one run fails, another run must be made by a different pilot. In addition to the similarity of the scenes, some of the dialogue is nearly identical. Star Wars also ends with an Elgarian march, like The Dam Busters. Gilbert Taylor, responsible for special effects photography on The Dam Busters, was the director of photography for Star Wars.>>
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by johnnydeep » Thu Aug 05, 2021 7:23 pm

VictorBorun wrote:
Thu Aug 05, 2021 4:42 pm
a curving chain of craters that begins with Rutherfurd in the south then arcs across the floor in a counterclockwise direction forming a sequence of ever diminishing diameters. From largest to smallest, these craters are designated Clavius D, C, N, J, and JA. This sequence of diminishing craters has proved a useful tool for amateur astronomers who want to test the resolution of their small telescopes.

This chain looks regular, does not it?

Like there was a hitting asteroid that at first merely touched the surface, but gradually hit after hit made ever more steep jumps and hits.
Besides it was tumbling and its spin made a curve path of its hits.
[ FYI: your link is broken because, since you left off the "http://" prefix, it was assumed to be an address relative to asterisk.apod.com. ]

I suspect that arc of diminishing craters is merely a pleasing optical happenstance and that the craters are unrelated.
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by neufer » Thu Aug 05, 2021 9:57 pm

johnnydeep wrote:
Thu Aug 05, 2021 7:23 pm

I suspect that arc of diminishing craters is merely a pleasing optical happenstance and that the craters are unrelated.
https://en.wikipedia.org/wiki/Clavius_(crater) wrote:
<<In October 2020, NASA confirmed the existence of molecular water near Clavius, at concentrations of up to 412 parts per million. Several ways have been suggested. The water could be trapped into tiny beadlike structures in the soil that form out of the high heat created by micrometeorite impacts. The water might also be sheltered between lunar soil grains. Another possibility is from very small asteroid strikes, such as a rubble pile from a much more massive "parent" asteroid collision. Pulled apart in its descent to the lunar surface similar to Comet Shoemaker–Levy 9, and hitting the surface in a modest dispersal area with a small mass at low, oblique impact angle and bouncing could allow some water to remain in the lithic matrix. The carbonaceous chondrite class is often water-rich, and the CI sub group are as much as 22% water.

C chondrites contain a high proportion of carbon (up to 3%), which is in the form of graphite , carbonates and organic compounds, including amino acids. In addition, they contain water and minerals that have been modified by the influence of water. The carbonaceous chondrites were not exposed to higher temperatures, so that they are hardly changed by thermal processes. Some carbonaceous chondrites, such as the Allende meteorite, contain calcium-aluminum-rich inclusions (CAIs). These are compounds that emerged early from the primeval solar nebula, condensed out and represent the oldest minerals formed in the solar system. Another carbonaceous chondrite, the Flensburg meteorite (2019), provides evidence of the earliest known occurrence of liquid water in the young solar system to date.>>
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by johnnydeep » Fri Aug 06, 2021 2:57 pm

neufer wrote:
Thu Aug 05, 2021 9:57 pm
johnnydeep wrote:
Thu Aug 05, 2021 7:23 pm

I suspect that arc of diminishing craters is merely a pleasing optical happenstance and that the craters are unrelated.
https://en.wikipedia.org/wiki/Clavius_(crater) wrote:
<<In October 2020, NASA confirmed the existence of molecular water near Clavius, at concentrations of up to 412 parts per million. Several ways have been suggested. The water could be trapped into tiny beadlike structures in the soil that form out of the high heat created by micrometeorite impacts. The water might also be sheltered between lunar soil grains. Another possibility is from very small asteroid strikes, such as a rubble pile from a much more massive "parent" asteroid collision. Pulled apart in its descent to the lunar surface similar to Comet Shoemaker–Levy 9, and hitting the surface in a modest dispersal area with a small mass at low, oblique impact angle and bouncing could allow some water to remain in the lithic matrix. The carbonaceous chondrite class is often water-rich, and the CI sub group are as much as 22% water.

C chondrites contain a high proportion of carbon (up to 3%), which is in the form of graphite , carbonates and organic compounds, including amino acids. In addition, they contain water and minerals that have been modified by the influence of water. The carbonaceous chondrites were not exposed to higher temperatures, so that they are hardly changed by thermal processes. Some carbonaceous chondrites, such as the Allende meteorite, contain calcium-aluminum-rich inclusions (CAIs). These are compounds that emerged early from the primeval solar nebula, condensed out and represent the oldest minerals formed in the solar system. Another carbonaceous chondrite, the Flensburg meteorite (2019), provides evidence of the earliest known occurrence of liquid water in the young solar system to date.>>
Whether water was brought by a rubble pile or not, I still think it more likely that those nicely decreasing in size craters are not related. One way to tell is to date all of them and if they are all the same age that would tend to favor the theory that they are related.
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by Chris Peterson » Fri Aug 06, 2021 3:14 pm

VictorBorun wrote:
Thu Aug 05, 2021 4:42 pm
a curving chain of craters that begins with Rutherfurd in the south then arcs across the floor in a counterclockwise direction forming a sequence of ever diminishing diameters. From largest to smallest, these craters are designated Clavius D, C, N, J, and JA. This sequence of diminishing craters has proved a useful tool for amateur astronomers who want to test the resolution of their small telescopes.

This chain looks regular, does not it?

Like there was a hitting asteroid that at first merely touched the surface, but gradually hit after hit made ever more steep jumps and hits.
Besides it was tumbling and its spin made a curve path of its hits.
Not possible. These are craters, not pits. Each one represents the complete destruction of the body that created it.
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by Chris Peterson » Fri Aug 06, 2021 3:17 pm

johnnydeep wrote:
Fri Aug 06, 2021 2:57 pm
Whether water was brought by a rubble pile or not, I still think it more likely that those nicely decreasing in size craters are not related. One way to tell is to date all of them and if they are all the same age that would tend to favor the theory that they are related.
You're probably right. But the only reasonable mechanism by which they could be related would be a series of impacts from a tidally disrupted parent body. It does happen.
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by johnnydeep » Fri Aug 06, 2021 3:31 pm

Chris Peterson wrote:
Fri Aug 06, 2021 3:17 pm
johnnydeep wrote:
Fri Aug 06, 2021 2:57 pm
Whether water was brought by a rubble pile or not, I still think it more likely that those nicely decreasing in size craters are not related. One way to tell is to date all of them and if they are all the same age that would tend to favor the theory that they are related.
You're probably right. But the only reasonable mechanism by which they could be related would be a series of impacts from a tidally disrupted parent body. It does happen.
Yes, as was shown here some weeks ago to explain a nice straight line of diminishing craters (I forget on which body that was). For some reason, a resulting straight line of craters seems (much?) more likely to arise than a nice arc (I have the 20+ pieces of the comet that disintegrated while striking Jupiter in 1994 in mind).
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by Chris Peterson » Fri Aug 06, 2021 3:56 pm

johnnydeep wrote:
Fri Aug 06, 2021 3:31 pm
Chris Peterson wrote:
Fri Aug 06, 2021 3:17 pm
johnnydeep wrote:
Fri Aug 06, 2021 2:57 pm
Whether water was brought by a rubble pile or not, I still think it more likely that those nicely decreasing in size craters are not related. One way to tell is to date all of them and if they are all the same age that would tend to favor the theory that they are related.
You're probably right. But the only reasonable mechanism by which they could be related would be a series of impacts from a tidally disrupted parent body. It does happen.
Yes, as was shown here some weeks ago to explain a nice straight line of diminishing craters (I forget on which body that was). For some reason, a resulting straight line of craters seems (much?) more likely to arise than a nice arc (I have the 20+ pieces of the comet that disintegrated while striking Jupiter in 1994 in mind).
Whether you get a line or an arc depends upon the separation of the bodies, as well as the rotation rate of the body that is impacted.
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by johnnydeep » Fri Aug 06, 2021 4:14 pm

Chris Peterson wrote:
Fri Aug 06, 2021 3:56 pm
johnnydeep wrote:
Fri Aug 06, 2021 3:31 pm
Chris Peterson wrote:
Fri Aug 06, 2021 3:17 pm


You're probably right. But the only reasonable mechanism by which they could be related would be a series of impacts from a tidally disrupted parent body. It does happen.
Yes, as was shown here some weeks ago to explain a nice straight line of diminishing craters (I forget on which body that was). For some reason, a resulting straight line of craters seems (much?) more likely to arise than a nice arc (I have the 20+ pieces of the comet that disintegrated while striking Jupiter in 1994 in mind).
Whether you get a line or an arc depends upon the separation of the bodies, as well as the rotation rate of the body that is impacted.
But a simple arc? Wouldn't a random "scatter pattern" be the more common result?
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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by VictorBorun » Fri Aug 06, 2021 4:21 pm

johnnydeep wrote:
Fri Aug 06, 2021 4:14 pm
Chris Peterson wrote:
Fri Aug 06, 2021 3:56 pm
johnnydeep wrote:
Fri Aug 06, 2021 3:31 pm


Yes, as was shown here some weeks ago to explain a nice straight line of diminishing craters (I forget on which body that was). For some reason, a resulting straight line of craters seems (much?) more likely to arise than a nice arc (I have the 20+ pieces of the comet that disintegrated while striking Jupiter in 1994 in mind).
Whether you get a line or an arc depends upon the separation of the bodies, as well as the rotation rate of the body that is impacted.
But a simple arc? Wouldn't a random "scatter pattern" be the more common result?
on an orbit with some excentricity there is some change of orbital velocity. If a body gets fragmented, the acceleration separates the fragments along the orbit. Then we get a chain of fragments travelling along the same orbit… or do we?

Or suppose a last moment fragmentation. An asteroid is falling down to Moon and is tidally disrupted while falling. And the free fall acceleration separates the fragments along the path of the fall, as Galileo suggested for any falling body were the gravity mass of a body any different from its inertial mass.

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by Chris Peterson » Fri Aug 06, 2021 4:48 pm

johnnydeep wrote:
Fri Aug 06, 2021 4:14 pm
Chris Peterson wrote:
Fri Aug 06, 2021 3:56 pm
johnnydeep wrote:
Fri Aug 06, 2021 3:31 pm


Yes, as was shown here some weeks ago to explain a nice straight line of diminishing craters (I forget on which body that was). For some reason, a resulting straight line of craters seems (much?) more likely to arise than a nice arc (I have the 20+ pieces of the comet that disintegrated while striking Jupiter in 1994 in mind).
Whether you get a line or an arc depends upon the separation of the bodies, as well as the rotation rate of the body that is impacted.
But a simple arc? Wouldn't a random "scatter pattern" be the more common result?
No. The disrupted bodies will be moving in the same orbit (with only the true anomaly varying slightly). So the impact will be essentially linear, arcing only to the degree the impacted body rotates between hits.

This assumes a typical breakup, where the rubble pile is disrupted by the Earth or the Moon very shortly before impact. Of course, a body can be disrupted by another planet, or long before impact, in which case the individual parts will be perturbed and their orbits will deviate. But if that happens, I doubt we'd ever connect their final impacts to a common parent. Nothing would make that evidence based on appearance alone.
Chris

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Re: APOD: Tycho and Clavius (2021 Aug 05)

Post by johnnydeep » Fri Aug 06, 2021 6:11 pm

Chris Peterson wrote:
Fri Aug 06, 2021 4:48 pm
johnnydeep wrote:
Fri Aug 06, 2021 4:14 pm
Chris Peterson wrote:
Fri Aug 06, 2021 3:56 pm


Whether you get a line or an arc depends upon the separation of the bodies, as well as the rotation rate of the body that is impacted.
But a simple arc? Wouldn't a random "scatter pattern" be the more common result?
No. The disrupted bodies will be moving in the same orbit (with only the true anomaly varying slightly). So the impact will be essentially linear, arcing only to the degree the impacted body rotates between hits.

This assumes a typical breakup, where the rubble pile is disrupted by the Earth or the Moon very shortly before impact. Of course, a body can be disrupted by another planet, or long before impact, in which case the individual parts will be perturbed and their orbits will deviate. But if that happens, I doubt we'd ever connect their final impacts to a common parent. Nothing would make that evidence based on appearance alone.
Ok. I don't see it, but that no doubt explains why I'm not an astronomer or astrophysicist.
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"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."