APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

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APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by APOD Robot » Sun Nov 29, 2020 5:05 am

Image Verona Rupes: Tallest Known Cliff in the Solar System

Explanation: Could you survive a jump off the tallest cliff in the Solar System? Quite possibly. Verona Rupes on Uranus' moon Miranda is estimated to be 20 kilometers deep -- ten times the depth of the Earth's Grand Canyon. Given Miranda's low gravity, it would take about 12 minutes for a thrill-seeking adventurer to fall from the top, reaching the bottom at the speed of a racecar -- about 200 kilometers per hour. Even so, the fall might be survivable given proper airbag protection. The featured image of Verona Rupes was captured by the passing Voyager 2 robotic spacecraft in 1986. How the giant cliff was created remains unknown, but is possibly related to a large impact or tectonic surface motion.

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Ann » Sun Nov 29, 2020 7:05 am



























The name "Miranda" for the moon hosting this tall cliff is surely a misnomer. Miranda has been stamped with a huge letter "L" for everyone to see, so clearly its name should be "Lucinda" or something! :D

Can anyone say where in this overview of Miranda (or Lucinda) we can see the tall cliff that is the subject of this APOD?

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by MadCat-75 » Sun Nov 29, 2020 8:46 am

Hi,

there is a scene in the short film "Wanderers" by Erik Wernquist, where tourists jump of this cliff.

https://vimeo.com/108650530

At minute 2:40

WWW

Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by WWW » Sun Nov 29, 2020 12:08 pm

The relative location of Verona Rupes can be found on this Wikimedia features map of Miranda:

https://commons.wikimedia.org/wiki/File ... iranda.png

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by De58te » Sun Nov 29, 2020 12:12 pm

Ann wrote:
Sun Nov 29, 2020 7:05 am

Can anyone say where in this overview of Miranda (or Lucinda) we can see the tall cliff that is the subject of this APOD?

Ann
My guess would be the dark shadow fingers seen at the south rim about 5:30 clock face. Although today's APOD has rotated the picture to about 6:30.

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Ann » Sun Nov 29, 2020 12:54 pm

Thanks, WWW and De58te!

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by orin stepanek » Sun Nov 29, 2020 1:38 pm

TallestCliff_Voyager2_1002.jpg

Looks a mess! Some of the area looks like frozen molten rock; and then the cliff looks Like it was lifted and sheared out of an upheaval of the ground! looking at Ann's insert of Miranda makes like the whole moon went through a tortuous past! :mrgreen:

PIA18185_Miranda's_Icy_Face.jpg
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Chris Peterson » Sun Nov 29, 2020 2:46 pm

orin stepanek wrote:
Sun Nov 29, 2020 1:38 pm
Looks a mess! Some of the area looks like frozen molten rock; and then the cliff looks Like it was lifted and sheared out of an upheaval of the ground! looking at Ann's insert of Miranda makes like the whole moon went through a tortuous past! :mrgreen:
It's probably all water ice, not rock. But at those temperatures, there is little difference in terms of geomorphology.
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Ann » Sun Nov 29, 2020 3:08 pm

Chris Peterson wrote:
Sun Nov 29, 2020 2:46 pm
orin stepanek wrote:
Sun Nov 29, 2020 1:38 pm
Looks a mess! Some of the area looks like frozen molten rock; and then the cliff looks Like it was lifted and sheared out of an upheaval of the ground! looking at Ann's insert of Miranda makes like the whole moon went through a tortuous past! :mrgreen:
It's probably all water ice, not rock. But at those temperatures, there is little difference in terms of geomorphology.
In simpler English:

At those temperatures. water ice is as hard as rock.

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by orin stepanek » Sun Nov 29, 2020 3:09 pm

Chris Peterson wrote:
Sun Nov 29, 2020 2:46 pm
orin stepanek wrote:
Sun Nov 29, 2020 1:38 pm
Looks a mess! Some of the area looks like frozen molten rock; and then the cliff looks Like it was lifted and sheared out of an upheaval of the ground! looking at Ann's insert of Miranda makes like the whole moon went through a tortuous past! :mrgreen:
It's probably all water ice, not rock. But at those temperatures, there is little difference in terms of geomorphology.

Ah! Yes; that makes sense! Thanks Chris!
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Chris Peterson » Sun Nov 29, 2020 3:11 pm

Ann wrote:
Sun Nov 29, 2020 3:08 pm
Chris Peterson wrote:
Sun Nov 29, 2020 2:46 pm
orin stepanek wrote:
Sun Nov 29, 2020 1:38 pm
Looks a mess! Some of the area looks like frozen molten rock; and then the cliff looks Like it was lifted and sheared out of an upheaval of the ground! looking at Ann's insert of Miranda makes like the whole moon went through a tortuous past! :mrgreen:
It's probably all water ice, not rock. But at those temperatures, there is little difference in terms of geomorphology.
In simpler English:

At those temperatures. water ice is as hard as rock.
Sort of, but not as descriptive. There are other materials that are as "hard as rock" that don't behave structurally like rock in a geological context. Which is actually why I put it the way I did... very cold water ice and rock will form similar structures under the influence of geological forces.
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by neufer » Sun Nov 29, 2020 3:54 pm

Chris Peterson wrote:
Sun Nov 29, 2020 3:11 pm
Ann wrote:
Sun Nov 29, 2020 3:08 pm
Chris Peterson wrote:
Sun Nov 29, 2020 2:46 pm

It's probably all water ice, not rock. But at those temperatures, there is little difference in terms of geomorphology.
In simpler English: At those temperatures. water ice is as hard as rock.
Sort of, but not as descriptive. There are other materials that are as "hard as rock" that don't behave structurally like rock in a geological context. Which is actually why I put it the way I did... very cold water ice and rock will form similar structures under the influence of geological forces.
  • The average density of granite is 2.7 g/cm3,
    its compressive strength usually lies above 200 MPa
    ..................................................................
    The average density of ice is 0.92 g/cm3,
    its compressive strength is ~3 MPa

    The average density of Miranda is 1.2 g/cm3,
    its surface gravity is 0.008 g
    ..................................................................
    Ergo: An ice mountain on Miranda is stronger than a granite mountain on Earth.
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Chris Peterson » Sun Nov 29, 2020 3:59 pm

neufer wrote:
Sun Nov 29, 2020 3:54 pm
Chris Peterson wrote:
Sun Nov 29, 2020 3:11 pm
Ann wrote:
Sun Nov 29, 2020 3:08 pm


In simpler English: At those temperatures. water ice is as hard as rock.
Sort of, but not as descriptive. There are other materials that are as "hard as rock" that don't behave structurally like rock in a geological context. Which is actually why I put it the way I did... very cold water ice and rock will form similar structures under the influence of geological forces.
  • The average density of granite is 2.7 g/cm3,
    its compressive strength usually lies above 200 MPa
    ..................................................................
    The average density of ice is 0.92 g/cm3,
    its compressive strength is ~3 MPa

    The average density of Miranda is 1.2 g/cm3,
    its surface gravity is 0.008 g
    ..................................................................
    Ergo: An ice mountain on Miranda is stronger than a granite mountain on Earth.
Except that understanding local geology in terms of broadly average characteristics puts one on thin ice. And maybe not the hardest of ice.
Chris

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by neufer » Sun Nov 29, 2020 5:40 pm

Chris Peterson wrote:
Sun Nov 29, 2020 3:59 pm
neufer wrote:
Sun Nov 29, 2020 3:54 pm
Chris Peterson wrote:
Sun Nov 29, 2020 3:11 pm

There are other materials that are as "hard as rock" that don't behave structurally like rock in a geological context. Which is actually why I put it the way I did... very cold water ice and rock will form similar structures under the influence of geological forces.
  • The average density of granite is 2.7 g/cm3,
    its compressive strength usually lies above 200 MPa
    ..................................................................
    The average density of ice is 0.92 g/cm3,
    its compressive strength is ~3 MPa

    The average density of Miranda is 1.2 g/cm3,
    its surface gravity is 0.008 g
    ..................................................................
    Ergo: An ice mountain on Miranda is stronger than a granite mountain on Earth.
Except that understanding local geology in terms of broadly average characteristics puts one on thin ice. And maybe not the hardest of ice.
The raw numbers can't just be taken for granite, however:
  • 200 MPa / (2,700 kg/m3 x 9.81 m/s2) = ~7.55 km
    vs. 1.34 km ESE headwall of the Great Trango Tower

    3 MPa / (920 kg/m3 x 0.079 m/s2) = ~41.3 km
    vs. ~20 km Verona Rupes.
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by johnnydeep » Sun Nov 29, 2020 7:49 pm

neufer wrote:
Sun Nov 29, 2020 3:54 pm
Chris Peterson wrote:
Sun Nov 29, 2020 3:11 pm
Ann wrote:
Sun Nov 29, 2020 3:08 pm


In simpler English: At those temperatures. water ice is as hard as rock.
Sort of, but not as descriptive. There are other materials that are as "hard as rock" that don't behave structurally like rock in a geological context. Which is actually why I put it the way I did... very cold water ice and rock will form similar structures under the influence of geological forces.
  • The average density of granite is 2.7 g/cm3,
    its compressive strength usually lies above 200 MPa
    ..................................................................
    The average density of ice is 0.92 g/cm3,
    its compressive strength is ~3 MPa

    The average density of Miranda is 1.2 g/cm3,
    its surface gravity is 0.008 g
    ..................................................................
    Ergo: An ice mountain on Miranda is stronger than a granite mountain on Earth.
Don't you need to account for the temperature of the ice? The colder it is, the stronger, no? And on Miranda, it's pretty cold.
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by neufer » Sun Nov 29, 2020 8:48 pm

johnnydeep wrote:
Sun Nov 29, 2020 7:49 pm

Don't you need to account for the temperature of the ice?

The colder it is, the stronger, no?
Probably... (I was using the Wikipedia 0º C value).
  • 200 MPa / (2,700 kg/m3 x 9.81 m/s2) = ~7.55 km
    vs. 1.34 km ESE headwall of the Great Trango Tower

    60 MPa / (920 kg/m3 x 0.079 m/s2) = ~825 km
    vs. ~20 km Verona Rupes.
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Guest » Mon Nov 30, 2020 6:52 pm

I have read in other sources that Verona Rupes is variably 12 km deep, 10 km, and even less than 10 km deep. This is the first time I've seen Verona Rupes measured at 20 km deep. Who determines the depth and what tools (mathematical or otherwise) are used to render these varying measurements?

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by SeedsofEarfth » Mon Nov 30, 2020 6:59 pm

The gravity potential at the top of Verona Rupes is estimated to be roughly .079 meters per second. Since you say a cliff diver would reach the speed of a race car by the time he hit bottom, how fast is that, exactly? I assume the physics for gravity and acceleration are involved in this assumption, right?

SeedsofEarfth

Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by SeedsofEarfth » Mon Nov 30, 2020 7:10 pm

The gravity potential at the top of Verona Rupes is estimated to be roughly .079 meters per second. Since you say a cliff diver would reach the speed of a race car by the time he hit bottom, how fast is that, exactly? I assume the physics for gravity and acceleration are involved in this assumption, right?

SeedsofEarfth

Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by SeedsofEarfth » Mon Nov 30, 2020 7:10 pm

The gravity potential at the top of Verona Rupes is estimated to be roughly .079 meters per second. Since you say a cliff diver would reach the speed of a race car by the time he hit bottom, how fast is that, exactly? I assume the physics for gravity and acceleration are involved in this assumption, right?

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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by Chris Peterson » Mon Nov 30, 2020 7:17 pm

SeedsofEarfth wrote:
Mon Nov 30, 2020 6:59 pm
The gravity potential at the top of Verona Rupes is estimated to be roughly .079 meters per second. Since you say a cliff diver would reach the speed of a race car by the time he hit bottom, how fast is that, exactly? I assume the physics for gravity and acceleration are involved in this assumption, right?
v = sqrt(2gd) = 56.2 m/s (126 mph)
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Re: APOD: Verona Rupes: Tallest Known Cliff in... (2020 Nov 29)

Post by neufer » Mon Nov 30, 2020 11:24 pm

Click to play embedded YouTube video.
Chris Peterson wrote:
Mon Nov 30, 2020 7:17 pm
SeedsofEarfth wrote:
Mon Nov 30, 2020 6:59 pm

The gravity potential at the top of Verona Rupes is estimated to be roughly .079 meters per second. Since you say a cliff diver would reach the speed of a race car by the time he hit bottom, how fast is that, exactly? I assume the physics for gravity and acceleration are involved in this assumption, right?
  • v = sqrt(2gd) = 56.2 m/s (126 mph)
Art Neuendorffer