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What is the highest point on Earth as measured from Earth's center?

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Re: What is the highest point on Earth as measured from Earth's center?

#31

Post by Svexav »

spurgu wrote: post #20
simcop2387 wrote: post #15

Which center? The centroid of the spheroid that is the earth (i.e. the point that's as close to equidistant from all points as possible)? The center of mass? The gravitational center (I think this would be the same as the center of mass, but i'm not positive)? I'd be curious how the different centers change the results.

I would assume all of these (add center of volume) to be quite close to each other for all practical intents and purposes, given how smooth Earth's surface is in the big picture: https://what-if.xkcd.com/46/

You would be wrong.

Make the problem simpler by thinking in 2 dimensions. Where's the center of the United States? There are an infinite number of different answers. Think about how many different map projections there are.

Now where is the center of the Earth? The point furthest from sea level? The point furthest from the surface? Do you include mountains, ocean basins, ocean trenches, etc.? What % of a substance has to be water before it doesn't count as part of the earth? The point furthest from the edge of the atmosphere? How do you determine where that is? Or is the center of mass? These are all going to give you wildly different answers.

Humanities questions cannot be easily solved scientifically.

Re: What is the highest point on Earth as measured from Earth's center?

#32

Post by ghaff »

krupan wrote: post #30

"That makes Chimborazo the closest point on Earth to the stars." That statement sold me. If I want to be on the top of any mountain now, it's that one.

It's not an easy mountain but it's of a substantially lower degree of difficulty than the high Himalayan peaks. It's harder than the lower Ecuador volcanoes for reasons of elevation and other factors and has glaciers, etc. like they do but the weather tends to be better than mountains much further north or south. (I've climbed other volcanoes there but only made it part way up Chimborazo.)

ADDED: i.e. so it's not unthinkable for a person in good physical shape who gets some winter hiking experience, has a fair bit of experience hiking up mountains overall, gets some glacier skills, and goes on a guided climb. Of course, people react to altitude a lot differently.

Re: What is the highest point on Earth as measured from Earth's center?

#33

Post by dikei »

Svexav wrote: post #31
spurgu wrote: post #20

Earlier quoted context omitted.

I would assume all of these (add center of volume) to be quite close to each other for all practical intents and purposes, given how smooth Earth's surface is in the big picture: https://what-if.xkcd.com/46/

You would be wrong. Make the problem simpler by thinking in 2 dimensions. Where's the center of the United States? There are an infinite number of different answers. Think about how many different map projections there are. Now where is the center of the Earth? The point furthest from sea level? The point furthest from the surface? Do you include mountains, ocean basins, ocean trenches, etc.? What % of a substance ha…

The variation cause by mountain or sea trench is absolutely tiny compared to the earth diameter, as explained by his xkcd's link.

Re: What is the highest point on Earth as measured from Earth's center?

#34

Post by everybodyknows »

krupan wrote: post #30

"That makes Chimborazo the closest point on Earth to the stars." That statement sold me. If I want to be on the top of any mountain now, it's that one.

The statement implies that by "Earth's center" the authors mean the center of mass, that being the point about which the body as a whole rotates.

The oceans however are part of Earth's mass, and kept in motion relative to the crust by tidal forces from the moon. This too, the piece neglects.

Calculation of the magnitude of tidal effect might be a fun exercise for someone whose calculus skills are less atrophied than my own ...

Re: What is the highest point on Earth as measured from Earth's center?

#35

Post by Steko »

jake-low wrote: post #11
SilasX wrote: post #2

>You may be surprised to learn that Everest is not the tallest mountain on Earth, either. That honor belongs to Mauna Kea, a volcano on the Big Island of Hawaii. Mauna Kea originates deep beneath the Pacific Ocean, and rises more than 33,500 feet from base to peak. Can someone explain this? How do you differentiate "the mountain" from "the rest of the earth that it comes out of"? (Side note: the issue of "tallest mou…

The article is likely referring to the estimated dry prominence of Mauna Kea. Topographic prominence [1] measures the height of a peak relative to its lowest surrounding contour line (that doesn't also contain another, taller peak). Usually the ocean's surface is considered "flat ground" when computing this measure (called a "wet prominence"), but one can alternatively imagine the Earth to have no water, and compute…

> The article is likely referring to the estimated dry prominence of Mauna Kea.

It's talking around a mountain's "surrounding base" which is a related concept but doesn't take you in the absurd direction of 'drawing a circle around yourself in the challenger deep and claiming everything else is part of Everest'.

There is no precise definition of surrounding base, but Denali, Mount Kilimanjaro and Nanga Parbat are possible candidates for the tallest mountain on land by this measure. The bases of mountain islands are below sea level, and given this consideration Mauna Kea (4,207 m (13,802 ft) above sea level) is the world's tallest mountain and volcano, rising about 10,203 m (33,474 ft) from the Pacific Ocean floor. Ojos del Salado has the greatest rise on Earth—13,420 m (44,029 ft) from the summit[citation needed] to the bottom of the Atacama Trench about 560 km (350 mi) away, though most of this rise is not part of the mountain.

https://en.wikipedia.org/wiki/List_of_highest_mountains_on_E...

Re: What is the highest point on Earth as measured from Earth's center?

#36

Post by hannasanarion »

njarboe wrote: post #23
jake-low wrote: post #11

Earlier quoted context omitted.

The article is likely referring to the estimated dry prominence of Mauna Kea. Topographic prominence [1] measures the height of a peak relative to its lowest surrounding contour line (that doesn't also contain another, taller peak). Usually the ocean's surface is considered "flat ground" when computing this measure (called a "wet prominence"), but one can alternatively imagine the Earth to have no water, and compute…

From your link, the lower elevation of a dry prominence of Everest would be the lowest contour that encircles Everest. That won't be nearly as deep as Challenger Deep but a quick google search does not find the correct dry prominence for me.

The correct dry prominence of everest is the same as the regular prominence of everest, because there are no bodies of water between it and the nearest peaks.

Re: What is the highest point on Earth as measured from Earth's center?

#37

Post by desdiv »

jake-low wrote: post #29
wallace_f wrote: post #21

Earlier quoted context omitted.

>However, an apples-to-apples comparison would use the dry prominence of Everest too, which is the distance from the bottom of the Challenger Deep (-10,911m) to the summit. This would make Mauna Kea the second tallest mountain by topographic prominence if the Earth had no oceans What? This does not make sense, if I am not mistaken? Topographic prominence would place Mauna Kea as the tallest (highest peak from base co…

Think about it this way: imagine standing at the bottom of the Challenger Deep. Draw a small circle around yourself on the ocean floor. Now step outside the circle. Because you're standing on a spherical object (Earth), the area outside your circle isn't infinite like it would be on a plane. It's another finite region, which covers almost the entire Earth, and contains both yourself (standing just beside the lowest p…

>Draw a small circle around yourself on the ocean floor.

That circle encloses two areas. One roughly a square metre, and the other one roughly 5e8 km². In geology only the smaller area is used, and the smaller area does not contain the peak of the Everest and thus is not considered a valid base contour line of the Everest.

Re: What is the highest point on Earth as measured from Earth's center?

#38

Post by ghaff »

everybodyknows wrote: post #34
krupan wrote: post #30

"That makes Chimborazo the closest point on Earth to the stars." That statement sold me. If I want to be on the top of any mountain now, it's that one.

The statement implies that by "Earth's center" the authors mean the center of mass, that being the point about which the body as a whole rotates. The oceans however are part of Earth's mass, and kept in motion relative to the crust by tidal forces from the moon. This too, the piece neglects. Calculation of the magnitude of tidal effect might be a fun exercise for someone whose calculus skills are less atrophied than…

Given the depth of the crust relative to the radius of the earth, I'm going to guess that to a first or even a second approximation, the center of the earth is pretty much the center of the earth whatever type of center you care to choose.

Re: What is the highest point on Earth as measured from Earth's center?

#39

Post by blendo »

So is the peak of Chimborazo the point on Earth with the lowest delta-v to orbit?

Compared to a sea level equatorial launch, https://space.stackexchange.com/questions/8486/where-is-the-... claims a 0.2% gravitational advantage due to height, and a 0.1% advantage due to rotational velociy.

Small, but not nothing.

Re: What is the highest point on Earth as measured from Earth's center?

#40

Post by alanbernstein »

blendo wrote: post #39

So is the peak of Chimborazo the point on Earth with the lowest delta-v to orbit? Compared to a sea level equatorial launch, https://space.stackexchange.com/questions/8486/where-is-the-... claims a 0.2% gravitational advantage due to height, and a 0.1% advantage due to rotational velociy. Small, but not nothing.

Maybe, but how are you going to carry a rocket up there? Even building a rocket sled up a mountain seems infeasible.
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