Starship Asterisk*

Chris Peterson wrote: ↑Sat Nov 04, 2023 2:07 pm

johnnydeep wrote: ↑Sat Nov 04, 2023 1:49 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 1:22 pm

There is no evidence of "exploded planets" in the Solar System (and no physics to explain such a thing). Asteroids are remnants of material that failed (probably due to gravitational resonance zones created by the gas giants) to coalesce into planets. The total mass of all the asteroids in the Solar System is about 3% of the mass of the Moon. Nowhere near enough material to point back to any planet.

I won't comment on the "exploded planet" theory (however unlikely it may be), but on the OP's statement about "belts". Each of these asteroids does indeed appear to have an "equatorial" belt or ridge, though the ridge on Dinkinesh itself is much more obvious than the ridge - if it is in fact more than an accidental artifact of perspective - on its moon. A few other moons of planets also exhibit ridges. Is there a good explanation for them?

Because they rotate. That means there are different forces present at the equator than near the poles... and in the common case of these things being "rubble piles" it isn't unexpected for material to accumulate around the equator. The YORP effect can result in asteroids spinning up, creating increased distortion and eventually the ejection of material and possible formation of a binary (as with today's APO). Here's an example of such a system being simulated mathematically:
.

Click to play embedded YouTube video.

AVAO wrote: ↑Sat Nov 04, 2023 4:54 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 4:50 pm

AVAO wrote: ↑Sat Nov 04, 2023 4:35 pm


Well, I'm not entirely convinced by the simulation, as the belt formation would have to continuously decrease towards the poles. For many moons, however, the belt can be defined as an equatorial bulge untill only a very narrow ridge, with a clear and independent shape, as we can see for example on Saturn's moons Atlas, Pan or Iapetus. The simulation cannot or only insufficiently explain these phenomena.

Click to view full size image

This image of Atlas was taken by Cassini’s narrow-angle camera during a close flyby on April 12, 2017. Image credit: NASA / JPL-Caltech / Space Science Institute.

Click to view full size image

"New image of Saturn’s tiny moon Pan, which orbits inside the Encke Gap of Saturn’s rings. A thin “skirt” or ridge of material surrounds the moon’s equator, giving it a "ravioli shaped" appearance. Photo Credit: NASA/JPL-Caltech/Space Science Institute/Ian Regan"

Click to view full size image

Click to view full size image

Credit: Saturn moon Iapetus NASA/JPL/Space Science Institute



Credit: Saturn moon Iapetus NASA/JPL/Space Science Institute

In all the cases it is likely a consequence of rotation, however, even if the rubble pile model isn't always the mechanism.

Yes - I totally agree with that.

Lasse H wrote: ↑Sat Nov 04, 2023 12:32 pm Certainly a very nice asteroid!
Something struck me about the legend to the photo – it's an unsystematic mixture of metric and Imperial units:

... a distance of just over 400 kilometers

... at 4.5 kilometer per second
or around 10,000 miles per hour

... less than 800 meters
(about 0.5 miles)

... only about 220 meters

What was the distance in miles? What was the speed in km/hour? Or miles per second? How big is the moon in feet (or yards)?

It would be nice if USA, Myanmar, Liberia and Samoa would also adopt metrics - and thus join the other 190 countries in the world.

Simscale wrote:

When NASA Lost a Spacecraft Due to a Metric Math Mistake

In September of 1999, after almost 10 months of travel to Mars, the Mars Climate Orbiter burned and broke into pieces. On a day when NASA engineers were expecting to celebrate, the ground reality turned out to be completely different, all because someone failed to use the right units, i.e., the metric units!
...
A NASA review board found that the problem was in the software controlling the orbiter’s thrusters. The software calculated the force that the thrusters needed to exert in pounds of force. A second piece of code that read this data assumed it was in the metric unit—“newtons per square meter”.

During the design phase, the propulsion engineers at Lockheed Martin in Colorado expressed force in pounds. However, it was standard practice to convert to metric units for space missions. Engineers at NASA’s Jet Propulsion Lab assumed the conversion had been made. This navigation mishap pushed the spacecraft dangerously close to the planet’s atmosphere where it presumably burned and broke into pieces, killing the mission on a day when engineers had expected to celebrate the craft’s entry into Mars’ orbit.

Chris Peterson wrote: ↑Sat Nov 04, 2023 4:50 pm

AVAO wrote: ↑Sat Nov 04, 2023 4:35 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 2:07 pm

Because they rotate. That means there are different forces present at the equator than near the poles... and in the common case of these things being "rubble piles" it isn't unexpected for material to accumulate around the equator. The YORP effect can result in asteroids spinning up, creating increased distortion and eventually the ejection of material and possible formation of a binary (as with today's APO). Here's an example of such a system being simulated mathematically:
.

Click to play embedded YouTube video.

Well, I'm not entirely convinced by the simulation, as the belt formation would have to continuously decrease towards the poles. For many moons, however, the belt can be defined as an equatorial bulge untill only a very narrow ridge, with a clear and independent shape, as we can see for example on Saturn's moons Atlas, Pan or Iapetus. The simulation cannot or only insufficiently explain these phenomena.

Click to view full size image

This image of Atlas was taken by Cassini’s narrow-angle camera during a close flyby on April 12, 2017. Image credit: NASA / JPL-Caltech / Space Science Institute.

Click to view full size image

"New image of Saturn’s tiny moon Pan, which orbits inside the Encke Gap of Saturn’s rings. A thin “skirt” or ridge of material surrounds the moon’s equator, giving it a "ravioli shaped" appearance. Photo Credit: NASA/JPL-Caltech/Space Science Institute/Ian Regan"

Click to view full size image

Click to view full size image

Credit: Saturn moon Iapetus NASA/JPL/Space Science Institute



Credit: Saturn moon Iapetus NASA/JPL/Space Science Institute

In all the cases it is likely a consequence of rotation, however, even if the rubble pile model isn't always the mechanism.

AVAO wrote: ↑Sat Nov 04, 2023 4:35 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 2:07 pm

johnnydeep wrote: ↑Sat Nov 04, 2023 1:49 pm

I won't comment on the "exploded planet" theory (however unlikely it may be), but on the OP's statement about "belts". Each of these asteroids does indeed appear to have an "equatorial" belt or ridge, though the ridge on Dinkinesh itself is much more obvious than the ridge - if it is in fact more than an accidental artifact of perspective - on its moon. A few other moons of planets also exhibit ridges. Is there a good explanation for them?

Because they rotate. That means there are different forces present at the equator than near the poles... and in the common case of these things being "rubble piles" it isn't unexpected for material to accumulate around the equator. The YORP effect can result in asteroids spinning up, creating increased distortion and eventually the ejection of material and possible formation of a binary (as with today's APO). Here's an example of such a system being simulated mathematically:
.

Click to play embedded YouTube video.

Well, I'm not entirely convinced by the simulation, as the belt formation would have to continuously decrease towards the poles. For many moons, however, the belt can be defined as an equatorial bulge untill only a very narrow ridge, with a clear and independent shape, as we can see for example on Saturn's moons Atlas, Pan or Iapetus. The simulation cannot or only insufficiently explain these phenomena.

Click to view full size image

This image of Atlas was taken by Cassini’s narrow-angle camera during a close flyby on April 12, 2017. Image credit: NASA / JPL-Caltech / Space Science Institute.

Click to view full size image

"New image of Saturn’s tiny moon Pan, which orbits inside the Encke Gap of Saturn’s rings. A thin “skirt” or ridge of material surrounds the moon’s equator, giving it a "ravioli shaped" appearance. Photo Credit: NASA/JPL-Caltech/Space Science Institute/Ian Regan"

Click to view full size image

Click to view full size image

Credit: Saturn moon Iapetus NASA/JPL/Space Science Institute



Credit: Saturn moon Iapetus NASA/JPL/Space Science Institute

Chris Peterson wrote: ↑Sat Nov 04, 2023 2:07 pm

johnnydeep wrote: ↑Sat Nov 04, 2023 1:49 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 1:22 pm

There is no evidence of "exploded planets" in the Solar System (and no physics to explain such a thing). Asteroids are remnants of material that failed (probably due to gravitational resonance zones created by the gas giants) to coalesce into planets. The total mass of all the asteroids in the Solar System is about 3% of the mass of the Moon. Nowhere near enough material to point back to any planet.

I won't comment on the "exploded planet" theory (however unlikely it may be), but on the OP's statement about "belts". Each of these asteroids does indeed appear to have an "equatorial" belt or ridge, though the ridge on Dinkinesh itself is much more obvious than the ridge - if it is in fact more than an accidental artifact of perspective - on its moon. A few other moons of planets also exhibit ridges. Is there a good explanation for them?

Because they rotate. That means there are different forces present at the equator than near the poles... and in the common case of these things being "rubble piles" it isn't unexpected for material to accumulate around the equator. The YORP effect can result in asteroids spinning up, creating increased distortion and eventually the ejection of material and possible formation of a binary (as with today's APO). Here's an example of such a system being simulated mathematically:
.

Click to play embedded YouTube video.

Chris Peterson wrote: ↑Sat Nov 04, 2023 2:07 pm

johnnydeep wrote: ↑Sat Nov 04, 2023 1:49 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 1:22 pm

There is no evidence of "exploded planets" in the Solar System (and no physics to explain such a thing). Asteroids are remnants of material that failed (probably due to gravitational resonance zones created by the gas giants) to coalesce into planets. The total mass of all the asteroids in the Solar System is about 3% of the mass of the Moon. Nowhere near enough material to point back to any planet.

I won't comment on the "exploded planet" theory (however unlikely it may be), but on the OP's statement about "belts". Each of these asteroids does indeed appear to have an "equatorial" belt or ridge, though the ridge on Dinkinesh itself is much more obvious than the ridge - if it is in fact more than an accidental artifact of perspective - on its moon. A few other moons of planets also exhibit ridges. Is there a good explanation for them?

Because they rotate. That means there are different forces present at the equator than near the poles... and in the common case of these things being "rubble piles" it isn't unexpected for material to accumulate around the equator. The YORP effect can result in asteroids spinning up, creating increased distortion and eventually the ejection of material and possible formation of a binary (as with today's APO). Here's an example of such a system being simulated mathematically:
.

Click to play embedded YouTube video.

johnnydeep wrote: ↑Sat Nov 04, 2023 1:49 pm

Chris Peterson wrote: ↑Sat Nov 04, 2023 1:22 pm

Roy wrote: ↑Sat Nov 04, 2023 1:14 pm Clearly fragments of an exploded planet. Each has a belt of stronger rock layer across the middle. This can only occur under planetary geological processes.

There is no evidence of "exploded planets" in the Solar System (and no physics to explain such a thing). Asteroids are remnants of material that failed (probably due to gravitational resonance zones created by the gas giants) to coalesce into planets. The total mass of all the asteroids in the Solar System is about 3% of the mass of the Moon. Nowhere near enough material to point back to any planet.

I won't comment on the "exploded planet" theory (however unlikely it may be), but on the OP's statement about "belts". Each of these asteroids does indeed appear to have an "equatorial" belt or ridge, though the ridge on Dinkinesh itself is much more obvious than the ridge - if it is in fact more than an accidental artifact of perspective - on its moon. A few other moons of planets also exhibit ridges. Is there a good explanation for them?

The first asteroid to be visited by NASA’s Lucy mission now has a name. The International Astronomical Union has approved the name (152830) Dinkinesh for the tiny main belt asteroid that the Lucy spacecraft will encounter on November 1, 2023. “Dinkinesh”, or ድንቅነሽ in Amharic, is the Ethiopian name for the human-ancestor fossil, also known as Lucy, which was found in that country and currently curated there. Dinkinesh means “you are marvelous” in Amharic.

Chris Peterson wrote: ↑Sat Nov 04, 2023 1:22 pm

Roy wrote: ↑Sat Nov 04, 2023 1:14 pm Clearly fragments of an exploded planet. Each has a belt of stronger rock layer across the middle. This can only occur under planetary geological processes.

There is no evidence of "exploded planets" in the Solar System (and no physics to explain such a thing). Asteroids are remnants of material that failed (probably due to gravitational resonance zones created by the gas giants) to coalesce into planets. The total mass of all the asteroids in the Solar System is about 3% of the mass of the Moon. Nowhere near enough material to point back to any planet.

Roy wrote: ↑Sat Nov 04, 2023 1:14 pm Clearly fragments of an exploded planet. Each has a belt of stronger rock layer across the middle. This can only occur under planetary geological processes.