Starship Asterisk*

Comet Schwassmann-Wachmann 3 Fragments

Explanation: Periodic comet 73P/Schwassmann-Wachmann 3 has broken up at least twice. A cosmic souffle of ice and dust left over from the early solar system, this comet was first seen to split into several large pieces during the close-in part of its orbit in 1995. However, in the 2006 passage, it disintegrated into dozens of fragments that stretched several degrees across the sky. Since comets are relatively fragile, stresses from heat, gravity and outgassing, for example, could be responsible for their tendency to break up in such a spectacular fashion when they near the hot Sun. The Hubble Space Telescope [url=https://hubblesite.org/contents/media/v ... Video.html" >recorded, in 2006, the featured sharp view</a> of prolific <a href="ap060426.html]Fragment B[/url], itself trailing a multitude of smaller pieces, each with its own cometary coma and tail. The picture spans over 3,000 kilometers at the comet's distance of 32 million kilometers from planet Earth.

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Cool comet picture and cool comet comments! So I was compelled completely to comment cooly. Thanks!

Some explanation for the ignorant (me) please?

The break-up may be moderately explosive, like a geyser eruption on Earth, but how do the fragments become so separated? Are they scattered along the orbit of the parent comet? Or, as all their tails are aligned, but they are all along the same line, in different orbits with slightly different radii? Are they 'blown' away from the parent by the Solar Wind, acting more on smaller objects?
Thanks!
John

JohnD wrote: ↑Sun Sep 03, 2023 9:44 am Some explanation for the ignorant (me) please?

Hi JohnD,

I know you know you’re not ignorant and are smart else you wouldn’t ask questions.

Thanks! Now you’ve got me curious. The not so smart one… but pretty silly one!

Indeed, emc, only the truly ignorant don't ask questions.

I know that this site will inform me.
John

JohnD wrote: ↑Sun Sep 03, 2023 10:12 am Indeed, emc, only the truly ignorant don't ask questions.

I know that this site will inform me.
John

Yes sir to that!

JohnD wrote: ↑Sun Sep 03, 2023 9:44 am Some explanation for the ignorant (me) please?

The break-up may be moderately explosive, like a geyser eruption on Earth, but how do the fragments become so separated? Are they scattered along the orbit of the parent comet? Or, as all their tails are aligned, but they are all along the same line, in different orbits with slightly different radii? Are they 'blown' away from the parent by the Solar Wind, acting more on smaller objects?
Thanks!
John

Cometary debris always lies in a sort of toroidal zone around the orbital path of the parent body. It initially just drifts from whatever momentum is provided by the release mechanism (and that's all we're seeing in this image, where the fragments are all recently produced and just a few thousand kilometers apart). Over time fragments drift forward or back because they have been displaced into higher or lower orbits, and they are perturbed by the effects of solar radiation, solar wind, P-R effect, and other mechanisms that act on small bodies in the Solar System.

Chris Peterson wrote: ↑Sun Sep 03, 2023 1:41 pm

JohnD wrote: ↑Sun Sep 03, 2023 9:44 am Some explanation for the ignorant (me) please?

The break-up may be moderately explosive, like a geyser eruption on Earth, but how do the fragments become so separated? Are they scattered along the orbit of the parent comet? Or, as all their tails are aligned, but they are all along the same line, in different orbits with slightly different radii? Are they 'blown' away from the parent by the Solar Wind, acting more on smaller objects?
Thanks!
John

Cometary debris always lies in a sort of toroidal zone around the orbital path of the parent body. It initially just drifts from whatever momentum is provided by the release mechanism (and that's all we're seeing in this image, where the fragments are all recently produced and just a few thousand kilometers apart). Over time fragments drift forward or back because they have been displaced into higher or lower orbits, and they are perturbed by the effects of solar radiation, solar wind, P-R effect, and other mechanisms that act on small bodies in the Solar System.

Thanks Chris! Nice explanation.
What’s P-R effect? Is it something about rotation?

The first link in the post takes us to a summary (on cometography .com) of observations since discovery in 1930. The period is approximately 5 years 4 months. Closest approach to earth has been from 5.7 (1930) to 6.8 (2006) million miles. This information prompts three questions.
1. What is the obliquity of the comet’s orbit to the plane of the earth’s orbit?
2. What is the estimated mass of the comet?
3. Where is the comet’s aphelion?
Not exactly a fourth question, relating to a potential impact, but do we have images of the comet for 2011, 2017, 2022 approaches that can be referenced.

emc wrote: ↑Sun Sep 03, 2023 2:09 pm

Chris Peterson wrote: ↑Sun Sep 03, 2023 1:41 pm

JohnD wrote: ↑Sun Sep 03, 2023 9:44 am Some explanation for the ignorant (me) please?

The break-up may be moderately explosive, like a geyser eruption on Earth, but how do the fragments become so separated? Are they scattered along the orbit of the parent comet? Or, as all their tails are aligned, but they are all along the same line, in different orbits with slightly different radii? Are they 'blown' away from the parent by the Solar Wind, acting more on smaller objects?
Thanks!
John

Cometary debris always lies in a sort of toroidal zone around the orbital path of the parent body. It initially just drifts from whatever momentum is provided by the release mechanism (and that's all we're seeing in this image, where the fragments are all recently produced and just a few thousand kilometers apart). Over time fragments drift forward or back because they have been displaced into higher or lower orbits, and they are perturbed by the effects of solar radiation, solar wind, P-R effect, and other mechanisms that act on small bodies in the Solar System.

Thanks Chris! Nice explanation.
What’s P-R effect? Is it something about rotation?

It's the Poynting-Roberstson effect, a drag force involving radiation pressure. It slowly clears the Solar System of dust by causing it to decay into the Sun. (Of course, we have comets that are always replenishing that dust.)

Roy wrote: ↑Sun Sep 03, 2023 2:11 pm The first link in the post takes us to a summary (on cometography .com) of observations since discovery in 1930. The period is approximately 5 years 4 months. Closest approach to earth has been from 5.7 (1930) to 6.8 (2006) million miles. This information prompts three questions.
1. What is the obliquity of the comet’s orbit to the plane of the earth’s orbit?
2. What is the estimated mass of the comet?
3. Where is the comet’s aphelion?
Not exactly a fourth question, relating to a potential impact, but do we have images of the comet for 2011, 2017, 2022 approaches that can be referenced.

The orbital inclination is 11.2°. Figure a typical cometary density of 0.6 g/cm³ and work it out for the volume of any particular fragment. I think the largest is now about 1 km diameter. Aphelion is at 5.2 AU.

emc.
Poynting–Robertson effect

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The Poynting-Robertson effect is a process by which interplanetary dust particles are slowly spiraled toward the Sun by solar radiation. This is because the orbital motion of the dust grains is counteracted by the radiation pressure component tangent to the motion.


Interpretation
The effect can be interpreted in two ways, depending on the reference system from which it is described.

From the perspective of the dust grain, the Sun's radiation appears to come from a slightly tilted angle toward the direction of motion (see light aberration); therefore, the absorption of this incident radiation by the grain (in other words, the transfer of momentum from it to it) results in a net force that opposes its orbital motion. This action is slow, since the angle of aberration is very small (solar radiation moves at the speed of light and the particle moves at a much lower speed).

From the perspective of the Sun (reference system at rest), the dust grain absorbs all the sunlight it receives from the radial direction, perpendicular to its movement and, therefore, its angular momentum does not change; however, the absorbing photons acquire mass (mass-energy equivalence), so to conserve angular momentum, their distance from the Sun must decrease.

Considering the re-emission of the energy absorbed by the grain, note that in the first case (seen from the grain) said re-emission is isotropic (same in all directions), and does not affect the movement. But seen from the Sun, the re-emission is anisotropic and the photons "carry" the angular momentum of the particle, a loss that must be compensated by approaching the Sun.

The action described is very slow, although its effect is cumulative over time: if a particle of a few micrometers (μm) is located at a distance from the Sun equivalent to Earth's orbit (one astronomical unit), it will need about seven thousand years to complete. the spiral towards the Sun. In very small particles (on the order of a fraction of μm or less) the radiation pressure of the Sun predominates and they have, therefore, outward motions. The Poynting-Robertson effect is also more intense near the Sun and tends to reduce the eccentricity of elliptical orbits.

References
JH Poynting (1903). Radiation in the Solar System: its effect on temperature and its pressure on small bodies. Philosophical Transactions of the Royal Society of London. ISBN 202 525-552.
HP Robertson (1937). Dynamic effects of radiation in the solar system. Monthly Notices of the Royal Astronomical Society. Number 97: pages 423-438.

Chris Peterson wrote: ↑Sun Sep 03, 2023 2:19 pm

emc wrote: ↑Sun Sep 03, 2023 2:09 pm

Chris Peterson wrote: ↑Sun Sep 03, 2023 1:41 pm
Cometary debris always lies in a sort of toroidal zone around the orbital path of the parent body. It initially just drifts from whatever momentum is provided by the release mechanism (and that's all we're seeing in this image, where the fragments are all recently produced and just a few thousand kilometers apart). Over time fragments drift forward or back because they have been displaced into higher or lower orbits, and they are perturbed by the effects of solar radiation, solar wind, P-R effect, and other mechanisms that act on small bodies in the Solar System.

Thanks Chris! Nice explanation.
What’s P-R effect? Is it something about rotation?

It's the Poynting-Roberstson effect, a drag force involving radiation pressure. It slowly clears the Solar System of dust by causing it to decay into the Sun. (Of course, we have comets that are always replenishing that dust.)

Thanks Chris! You’re a good explainer. I had googled P-R effect but just didn’t scroll far enough.

Sa Ji Tario wrote: ↑Sun Sep 03, 2023 2:53 pm emc.
Poynting–Robertson effect

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Thanks a bunch!

Comets are fascinating snowballs! I wonder how much of Earths
ocean came from comets? Kitty enjoying a sun bath!

In short: for most comets - unlike many humans - breaking up is easy to do.

Chris Peterson wrote: ↑Sun Sep 03, 2023 2:32 pm

Roy wrote: ↑Sun Sep 03, 2023 2:11 pm The first link in the post takes us to a summary (on cometography .com) of observations since discovery in 1930. The period is approximately 5 years 4 months. Closest approach to earth has been from 5.7 (1930) to 6.8 (2006) million miles. This information prompts three questions.
1. What is the obliquity of the comet’s orbit to the plane of the earth’s orbit?
2. What is the estimated mass of the comet?
3. Where is the comet’s aphelion?
Not exactly a fourth question, relating to a potential impact, but do we have images of the comet for 2011, 2017, 2022 approaches that can be referenced.

The orbital inclination is 11.2°. Figure a typical cometary density of 0.6 g/cm³ and work it out for the volume of any particular fragment. I think the largest is now about 1 km diameter. Aphelion is at 5.2 AU.

So, aphelion at Jupiter orbit. Radius of 500 meters, density 0.6 grams/cc. I get a mass of over 314 million metric tonnes. We trust the obliqueness of orbit keeps it away from intersection. Or Jupiter sweeps it up, as it did Shoemaker-Levy 9.

Roy wrote: ↑Sun Sep 03, 2023 7:05 pm

Chris Peterson wrote: ↑Sun Sep 03, 2023 2:32 pm

Roy wrote: ↑Sun Sep 03, 2023 2:11 pm The first link in the post takes us to a summary (on cometography .com) of observations since discovery in 1930. The period is approximately 5 years 4 months. Closest approach to earth has been from 5.7 (1930) to 6.8 (2006) million miles. This information prompts three questions.
1. What is the obliquity of the comet’s orbit to the plane of the earth’s orbit?
2. What is the estimated mass of the comet?
3. Where is the comet’s aphelion?
Not exactly a fourth question, relating to a potential impact, but do we have images of the comet for 2011, 2017, 2022 approaches that can be referenced.

The orbital inclination is 11.2°. Figure a typical cometary density of 0.6 g/cm³ and work it out for the volume of any particular fragment. I think the largest is now about 1 km diameter. Aphelion is at 5.2 AU.

So, aphelion at Jupiter orbit. Radius of 500 meters, density 0.6 grams/cc. I get a mass of over 314 million metric tonnes. We trust the obliqueness of orbit keeps it away from intersection. Or Jupiter sweeps it up, as it did Shoemaker-Levy 9.

It's an Earth orbit crossing body, so it has the potential to collide with Earth. Passing near Jupiter means that it is regularly perturbed, which means that long range orbital projections are impossible. Jupiter can as easily alter its orbit so it is more dangerous as it can make it less so.

orin stepanek wrote: ↑Sun Sep 03, 2023 4:24 pm fragb73p_hst_960.jpg
Comets are fascinating snowballs! I wonder how much of Earths
ocean came from comets?

If the Big Bang theory is correct, everything came from a single point. So wouldn’t everything have started together? Then during the expansion a P-R effect would have affected the distribution of matter? So there’s no human way of telling how much?

Chris Peterson wrote: ↑Sun Sep 03, 2023 2:19 pm

emc wrote: ↑Sun Sep 03, 2023 2:09 pm What’s P-R effect? Is it something about rotation?

It's the Poynting-Roberstson effect, a drag force involving radiation pressure. It slowly clears the Solar System of dust by causing it to decay into the Sun. (Of course, we have comets that are always replenishing that dust.)

Chris, Was my reply to Orin a correct usage of the P-R effect?

orin stepanek wrote: ↑Sun Sep 03, 2023 4:24 pm d1bb1bcb8e244356d0bd053e134344a3.jpg
Kitty enjoying a sun bath!

Orin,
Cute kitty. But a stretch for this thread.

Dang! I can’t remembered how to post the images. All I get is the image file name when I quote.

Thank you, Chris! So there are many effects on the debris from a cometary outburst, that pushed them into an expanding torus along the orbit of the parent object? Which brings me to the other point in my original Q - in the APOD picture, if you draw a line between the Comet and the centre of the bunch, is that line along the Comet's orbit?
OR, would that line point straight at the Sun, as the tails of the Comet and the debris are parallel?

I'm trying to orientate my view of the pic!

And thank you Sa Ji Tario! I was about the put my hand up and ask about the Poynting–Robertson effect, but emc got there first.

Gosh, I love a tutorial!
John

emc wrote: ↑Mon Sep 04, 2023 4:36 am

orin stepanek wrote: ↑Sun Sep 03, 2023 4:24 pm fragb73p_hst_960.jpg
Comets are fascinating snowballs! I wonder how much of Earths
ocean came from comets?

If the Big Bang theory is correct, everything came from a single point. So wouldn’t everything have started together? Then during the expansion a P-R effect would have affected the distribution of matter? So there’s no human way of telling how much?

Chris Peterson wrote: ↑Sun Sep 03, 2023 2:19 pm

emc wrote: ↑Sun Sep 03, 2023 2:09 pm What’s P-R effect? Is it something about rotation?

It's the Poynting-Roberstson effect, a drag force involving radiation pressure. It slowly clears the Solar System of dust by causing it to decay into the Sun. (Of course, we have comets that are always replenishing that dust.)

Chris, Was my reply to Orin a correct usage of the P-R effect?

orin stepanek wrote: ↑Sun Sep 03, 2023 4:24 pm d1bb1bcb8e244356d0bd053e134344a3.jpg
Kitty enjoying a sun bath!

Orin,
Cute kitty. But a stretch for this thread.

Dang! I can’t remembered how to post the images. All I get is the image file name when I quote.

I'm not Chris, but I don't think the P-R effect had much at all to do with the large scale aftermath of the Big Bang, or even the early formation of the Solar System. Comets (just "dirty snowballs" per Carl Sagan) were plentiful in the nascent Solar System, and were bombarding all forming planets and planetesimals. I'd bet that MOST of Earth's water originated from them. But I'm not sure if we could ever figure out an accurate graph of the Earth's water content over time from 4.5 Byrs ago to the present. Chris will no doubt helpfully point out where I'm "all wet" in my suppositions here, if necessary. :=)

And yes, the kitty is indeed a bit of a "stretch" for this thread! (yes, I do sometimes understand jokes!)

And to post images you either use the [img], [img2] or [img3] tags, using the buttons provided, or upload images from your local machine as attachments, using the Attachments tab interface below the posting text box.

emc wrote: ↑Mon Sep 04, 2023 4:36 am If the Big Bang theory is correct, everything came from a single point. So wouldn’t everything have started together? Then during the expansion a P-R effect would have affected the distribution of matter? So there’s no human way of telling how much?

Photons interact with matter in different ways, with different results. P-R specifically describes a form of drag that takes place in stellar systems, where you have small particles orbiting an active star. So P-R isn't really relevant to the structure of the Universe as it has followed from its origin.

(Of course, there wasn't even any dust in the Universe for light to interact with until after the first generation of stars had formed and started producing it, mainly when they exploded.)

JohnD wrote: ↑Mon Sep 04, 2023 9:06 am Thank you, Chris! So there are many effects on the debris from a cometary outburst, that pushed them into an expanding torus along the orbit of the parent object? Which brings me to the other point in my original Q - in the APOD picture, if you draw a line between the Comet and the centre of the bunch, is that line along the Comet's orbit?
OR, would that line point straight at the Sun, as the tails of the Comet and the debris are parallel?

I'm trying to orientate my view of the pic!

And thank you Sa Ji Tario! I was about the put my hand up and ask about the Poynting–Robertson effect, but emc got there first.

Gosh, I love a tutorial!
John

At this point, so early after fragmentation, I think all we're seeing is a diffusing cloud of particles where the location of those particles is largely determined by simple ballistics... the direction and speed at which they were ejected. Other forces have not yet begun to alter their positions very much, with the exception of the dust-sized particles, which are obviously being melted off the fragments and oriented by the solar wind.

Indeed, these large fragments, with their own tails, will largely spread out because of their small displacement from the parent body orbit, not external forces. Those pushed outwards will slowly fall behind, those pushed inwards will slowly advance. This is what creates toroidal debris fields over time, and in the case of bodies with Earth-crossing orbits, annual meteor showers.

emc wrote: ↑Mon Sep 04, 2023 4:36 am Dang! I can’t remembered how to post the images. All I get is the image file name when I quote.

How to post images

Chris Peterson wrote: ↑Mon Sep 04, 2023 1:46 pm

emc wrote: ↑Mon Sep 04, 2023 4:36 am If the Big Bang theory is correct, everything came from a single point. So wouldn’t everything have started together? Then during the expansion a P-R effect would have affected the distribution of matter? So there’s no human way of telling how much?

Photons interact with matter in different ways, with different results. P-R specifically describes a form of drag that takes place in stellar systems, where you have small particles orbiting an active star. So P-R isn't really relevant to the structure of the Universe as it has followed from its origin.

(Of course, there wasn't even any dust in the Universe for light to interact with until after the first generation of stars had formed and started producing it, mainly when they exploded.)

Thanks. You tha man! Cosmos Commentator man! That info puts some of the funny out of my joke. I love to talk with you Chris but am light years behind your cosmos oriented cranial compartment innards. I love you and hope you don’t mind me calling you my good friend. My good web friend!