There are places in oregon where you can look North and see Mount Adams in washington, and look south and see Mount Shasta in california. So basically the entire heigth of oregon. I've personally done this on Paulina Peak on several occasions.
Longest Lines of Sight on Earth
141–150 of 164 posts
Re: Longest Lines of Sight on Earth
#142You can see the sisters from Mt Adams, which is ~230 km away. I'm guessing there are several more of these that the site didn't catch. You can probably easily see Mt Rainier from 300 km+ standing at the right place. How were these determined? It would cool to see a write up on how it was done.
I know you can see Mount Rainier from Mary's Peak outside of Corvalais, which is 295km away. And I mentioned it in another comment here, but standing on paulina peak on a clear day, you can see both Mount Adams and Mount Shasta, more than the entire height of Oregon.
Re: Longest Lines of Sight on Earth
#143You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…
fwiw, this method doesn't seem to predict the list very well as its not a list of just the highest peaks in the world longest sightlines also depend on the surrounding topography that blocks or doesn't block a sightline this seems to account for the numerous Spanish entries on the list, where the large Spanish plain with high peaks on either side, enables you to see from 1 peak to the other, w/o anything on the plain…
It didn't claim to predict the list very well. Its purpose is to give intuition about how far around the Earth we can see.
Also it shows that simply being tall (airplanes go higher than Everest) doesn't get you on the list. The second paragraph puts an upper bound on sight lines between two mountains of a given size. The longest sight lines are pretty close to that limit. And it gives a simple experiment that anyone can carry out from an airplane which will let you see the curvature of the Earth.
Re: Longest Lines of Sight on Earth
#144You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…
How can I use this calculation to convince my flat-earther cousin that he is wrong?
I second the plane idea. Though actually the seat doesn't matter since he'll want to look out both windows to see the drop in both ways. Else he can just say, "The plane was tilted."
The connection between height and distance that this shows is why old ships used to have a crows nest. I love that connection, and you know how to do the calculation for why it matters. But proving that it is right is harder, particularly if you don't live near a large body of water.
With a bit more trig and a map you should be able to figure out the angle above the horizontal that a mountain somewhere in the visible distance should be. That angle should not be the same as it would be if it was flat. Verify it. Go driving somewhere else, verify it again using the same mountain.
But honestly, I'm personally most convinced by the fact that a phone call to someone in a different time zone makes it easy to verify that you're pointing different directions relative to the Sun.
As much as people like to point to things like eclipses, that relies on knowledge that you cannot verify yourself. I prefer verifications that you can duplicate with direct observation, without relying on outside experts. Because flat Earthers do not trust experts.
Re: Longest Lines of Sight on Earth
#145Mt. McKinley (6.194 m.) What country uses '.' as the thousands separator but speaks English? Or is this someone mixing their native language thousands separator with English? Or is there some weird interaction between country and language that makes this the preferred, or at minimum an acceptable standard form? I'm actually hoping it's one of the latter options, that would be something new to me.
TIL there's quite a few countries that use the decimal point as a thousands separator: https://en.wikipedia.org/wiki/Decimal_mark#Examples_of_use
Yeah the mix-up is a mess. I'm Dutch but as a programmer I've used dots for decimals my whole life. We should just get rid of the comma as decimal separator. Or do a worldwide survey for a representative sample and have a majority vote on it.
Then as for thousand separator, I always use spaces when I want to be clear (blog posts, comments), or the standard when I want to be correct (school reports, reports for our client). I've also seen apostrophe being used as unambiguous symbol but people frown at it. A little spacing is a natural way to group, especially on paper you can just write some more snugly than others and it's 100% unambiguous and perfectly legible no matter how many digits.
And while we're at it: yyyy-mm-dd, dd-mm-yyyy, mm/dd/yyyy or dd.mm.yyyy (in order of preference). Anything else is just incorrect imo. It's rare but some Dutch weirdos use our ordering neatly (ddmmyyyy) but then start using slashes, which Americans (with their incorrect though understandable mmddyyyy) typically use, and it's just impossible to disambiguate. Here too, let's have a global majority vote, at least for this calendar system -- but whatever you do, at least don't use different symbols at random.
Re: Longest Lines of Sight on Earth
#146Earlier quoted context omitted.
To be clear, they gave you the radius of the earth here, if you didn't already know it by heart? Otherwise, I'm not getting how you could solve this problem (assuming they didn't give you the angle that the arch formed, for example).
You don't need to know the radius of the earth unless you're asked for a numeric answer. The rope is 2 * pi * 10km longer than the Earth's circumference, since its radius is 10km more.
I think this is the wrong interpretation; your answer would be correct if the rope were hovering at a height of 10 km along the full length.
My interpretation is that the rope is pulled taut to a height of 10 km at a single point, so that it runs in a straight line to the horizon in either direction and lays on the ground the rest of the way; this is also relevant to the question of longest line of sight from a given height.
Re: Longest Lines of Sight on Earth
#147You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…
This is too simplistic of an approach. Suppose there is another 6km tall mountain just beyond the horizon, it will have a farther line of site to the peak of it than to the horizon just in front of it. This list seems to be a much more rigorous attempt.
Re: Longest Lines of Sight on Earth
#148Earlier quoted context omitted.
This exists already, from some pretty serious telecom companies, for distances of a few miles. The problem is that, in optical wavelengths, there's too much absorption and scattering in the atmosphere - fog, rain, storms, smog, smoke - that can disrupt the signal. But, in radio frequencies, this is how the microwave tower communications network works -- it's line-of-sight from tower to tower. https://www.wired.com/20…
Microwave LoS is still widely used to connect cell towers for example. Look at these circular dishes in this picture[1]. 1. https://ssl.c.photoshelter.com/img-get2/I0000JUzapOxgCs0/fit...
The microwave network is being resurrected between Chicago and NYC as a way to shorten the communications time for high frequency traders. Even after successively purchasing straighter and straighter rights of way for fiber, the microwave path is still shorter.
Re: Longest Lines of Sight on Earth
#149You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…
This is too simplistic of an approach. Suppose there is another 6km tall mountain just beyond the horizon, it will have a farther line of site to the peak of it than to the horizon just in front of it. This list seems to be a much more rigorous attempt.
Too simplistic of an approach for what?
It is meant to show how to calculate the position of the horizon on a smooth planet. Obviously your line of sight typically includes tall things beyond the horizon. However this calculation lets you know both how far away your horizon is, and how far beyond that a tall object could be seen if nothing else was in the way. Which puts an upper limit on how far away it can be.
A little bit of elementary geometry gives you a lot more than I expected it would the first time I amused myself by figuring the calculation.
Actually finding those points requires a lot more work, which this list does.
Re: Longest Lines of Sight on Earth
#150Earlier quoted context omitted.
To be clear, they gave you the radius of the earth here, if you didn't already know it by heart? Otherwise, I'm not getting how you could solve this problem (assuming they didn't give you the angle that the arch formed, for example).
You don't need to know the radius of the earth unless you're asked for a numeric answer. The rope is 2 * pi * 10km longer than the Earth's circumference, since its radius is 10km more.
Actually, it's a different question. Check out the second diagram linked to below: https://news.ycombinator.com/item?id=14863949
So yes, you could supply the answer in terms of r radius, but you do need to know the radius unless I'm missing something obvious.