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Longest Lines of Sight on Earth

beyondhorizons.eu

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Re: Longest Lines of Sight on Earth

#61

Post by URSpider94 »

jdironman wrote: post #53
newman8r wrote: post #8

Earlier quoted context omitted.

you'd still probably have one of those coordinates (of the tall mountain) remain the same, then find a tower that goes even further than the second point - although I never assume my logic is correct in geodesy/astronomy, especially when I'm tired edit* - in practice you're probably right

Laser powered ISPs anyone? I kid, but is this a possibility?

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/2015/03/spencer-harding-the-long-lines...

Re: Longest Lines of Sight on Earth

#62

Post by kbenson »

JulienSchmidt wrote: post #60
burkaman wrote: post #34

Earlier quoted context omitted.

.eu suggests this website was not created by native English speakers.

The website also has info pages about the authors: 3 from Spain and 1 from Andorra. The first language of all authors seems to be either Spanish or Catalan.

I guess that makes sense. I was just confused for a bit because I wasn't sure if the height was in in thousands of meters or miles (but if miles, it was odd in comparison to the kilometer distances). I looked up Mt. McKinley and converted the foot rating to meters to confirm that it was indeed thousands of meters, but the process got me wondering if page was mixing locale formats, or whether the my assumption that it should have been a comma to separate the thousands was wrong.

Re: Longest Lines of Sight on Earth

#63

Post by anyfoo »

seanmcdirmid wrote: post #52
kovek wrote: post #42

Earlier quoted context omitted.

I had this question worded differently asked to me when I interviewed to do an undergrad at Cambridge. If you have a rope that is wrapped around earth and you lift it off the ground as much as possible, and you see that it is 10km above the ground, then how long is the rope? I was not able to answer that question right away, and their hint to draw it helped a lot. I did not end up getting accepted.

It seems like one of those stupid brain teasers tech companies used to ask that are not very correlated with success but act as arbitrary filters.

In this case the "arbitrary filter" was filtering applicants to a university for very basic math knowledge, so I think assuming that it's correlated with success at that university is not very far fetched.

Re: Longest Lines of Sight on Earth

#65

Post by seanmcdirmid »

anyfoo wrote: post #63
seanmcdirmid wrote: post #52

Earlier quoted context omitted.

It seems like one of those stupid brain teasers tech companies used to ask that are not very correlated with success but act as arbitrary filters.

In this case the "arbitrary filter" was filtering applicants to a university for very basic math knowledge, so I think assuming that it's correlated with success at that university is not very far fetched.

Euclidean geometry games are hardly what people do in the real world, but if it floats your boat:

https://www.euclidea.xyz

I don't think after playing 20 or so levels I was much smarter for it. It turned out to be a bunch of rules that were extremely limited. You do begin to appreciate trig much more.

If you are being given a geometry subject test and are prepared for it, this is fair game. If the question is just given out of the blue as a brain teaser, then no, the university is not mining useful signals at all.

Re: Longest Lines of Sight on Earth

#66

Post by hondadriver »

kbenson wrote: post #62
JulienSchmidt wrote: post #60

Earlier quoted context omitted.

The website also has info pages about the authors: 3 from Spain and 1 from Andorra. The first language of all authors seems to be either Spanish or Catalan.

I guess that makes sense. I was just confused for a bit because I wasn't sure if the height was in in thousands of meters or miles (but if miles, it was odd in comparison to the kilometer distances). I looked up Mt. McKinley and converted the foot rating to meters to confirm that it was indeed thousands of meters, but the process got me wondering if page was mixing locale formats, or whether the my assumption that it…

In mainland Europe we only use the metric system, even when speaking or writing English.

Also it is common to stick to the comma as decimal separator and dot as thousands separator when writing English. This convention is independent of the language used.

Same goes for date notation, dd-mm-yyyy is used (almost) always.

In Windows or Linux for example you can select the English language with Dutch localisation. It's used by almost all software developers I know.

Re: Longest Lines of Sight on Earth

#67

Post by jackfoxy »

hodgesrm wrote: post #59
amacbride wrote: post #55

The Mount Hamilton to Yosemite view (168 miles), is the one that blew my mind when I first saw it: http://astronomy.snjr.net/blog/?p=416

Another good one is Mt. Diablo to Mt. Lassen, which is around 180 miles. That's the longest one I have seen in California. Tom Stienstra claimed it's 180 miles, which is a long way. [1] Other sources claim somewhat shorter distances. [1] http://www.sfgate.com/outdoors/article/Clear-viewing-from-Mo... (Oops somebody already pointed it out!)

Mt. Lassen, ha. If the atmospheric conditions are good enough you can see Mt. Shasta from Mt.Diablo. I know, I have seen it. That has to be around 250 miles (I don't have the exact figure). That would be 402 kilometers and worth a mention on this list.

Re: Longest Lines of Sight on Earth

#68

Post by flaie »

mrb wrote: post #21

And I thought seeing Mont Blanc from my town Le Creusot, France (a 216 km line of sight) was very long... not! Apparently it would only rank 6th from the bottom of this list!

You can see the Mont Blanc from the top of the Hohneck which is almost 250km. The first time when I was a kid, I couldn't trust my parents, it was like impossible to see something that far.

Re: Longest Lines of Sight on Earth

#69

Post by banku_brougham »

btilly wrote: post #25

You 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…

Excellent, i wish all explanatory posta were this direct and clear.

Re: Longest Lines of Sight on Earth

#70

Post by BurningFrog »

anyfoo wrote: post #63
seanmcdirmid wrote: post #52

Earlier quoted context omitted.

It seems like one of those stupid brain teasers tech companies used to ask that are not very correlated with success but act as arbitrary filters.

In this case the "arbitrary filter" was filtering applicants to a university for very basic math knowledge, so I think assuming that it's correlated with success at that university is not very far fetched.

Sure, but it also filters for people like me, who have seen this problem at least a dozen times.
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