Longest line of sight between two hills

Several years ago I climbed Mount Kenya, and was amazed to see Kilimanjaro poking out from above the clouds, plainly visible, at sunrise. (There was a temperature inversion, with clear air above a blanket of clouds below.)

I later checked an atlas and found that the distance between the two peaks is over 200 miles.

Is there a longer line of sight anywhere? I’m thinking these two mountains may be fairly unbeatable as they are very high, but have no major peaks between them. Everest is a lot higher, but is in a substantial mountain range, which must cut down the lines of sight.

Any hard data, or anecdotes. from mountaineering Dopers?

When I climbed Wheeler Peak (highest mountain in New Mexico) the folks I was hiking with identified the palest blue, most distant visible range as being in northern Colorado in the vicinity of Denver.



http://makeashorterlink.com/?Q1E923029 <— map for distance

I don’t think that would be as big a distance as what you’re talking about, but it was pretty damn impressive!

That’s probably the record - two pretty big mountains (19,000 ft and 14,000 ft off the top of my head) and nothing but flat plains in between.

From Mt Washington, the highest point in NH (6288’) you can make out Mt Whiteface in the Adirondacks, 130 miles away. These are two fairly low mountains in the grand scheme of things.

I’m guessing that if you know where to look you should be able to make out objects more than 200 miles distance from higher peaks, even with terrain in between.

My gut feeling (but only a gut feeling) is that you ought to be able to find such a distance considerably greater than 200 miles. Alaska’s Mt. McKinley (Denali) just might be a contender–it rises 18,000 feet above the surrounding land (i.e., not just 18,000 feet above sea level), which is considerably more than Mt. Everest, I believe.

In fact, I wonder what the tallest mountain is when measure from the surrounding land (of course, that would depend a great deal on the definition of “surrounding land”).

I’m pretty sure that there are spots in Idaho from which one can (barely) see Mt. Ranier, near the coast in Washington. And what’s the highest point on the Galapagos islands, and could one see any part of the mainland from there? I think that the Andes, as a range, are the highest above the surrounding terrain (being pretty much right next to the ocean), but unless there’s something significant on the Galapagos, your “second mountain” might have to be a particularly high wave. Alternately, there might be a region where the coastline is concave, and two tall Andes mountains face each other across water.

You goot chaeck this 360 view from Everest out.

You need Quick Time.

Apparently, on a clear day it is possible to see Mount Shasta in far Northern California from the summit of Mount Diablo in the San Francisco Bay Area. This is a distance of 245 miles.

If it helps any, I remember seeing this category in the Guinness Book years ago. Unfortunately, I don’t remember what the answer was.

Visual navigation from southern California east is easy. As soon as you clear the coast and get some altitude you can see Charleston Peak near Las Vegas, NV. Way before it disappears behind you, Mount Humphries at Flagstaff, AZ is in view. And you are over Route 66 (it’s now some Interstate but amounts the same thing) which you can follow the rest of the way before Humphries fades from view.

I know that traveling west on I-70 through Kansas, you can see the Rockies rise up from the plains from quite far away. You think they’re coming right up, but a couple hours later, they’re still in the distance. I don’t recollect from how far, but maybe someone on here can put a hard number on that.

And of course from the tops of Mts. Wilson and Palomar in California, Mauna Kea in Hawaii, etc., it’s quite possible to see Olympus Mons on Mars (through the telescope there) – a variable distance measured in the millions of miles! :slight_smile:

Hmmm. My best guess would be across the Ross ice shelf in Antarctica. Ok, the shelf itself is the size of France which means that you wouldn’t see all the way across, but mountain ranges curve around the edge of it with nothing but flat ice in between.
And on a good day, you do get significant temperature stratification which causes reflection between the layers resulting in mirages. The effect of this is being able to see (although not necessarily locate and identify with any precision) objects below the horizon.

If you really stretch that definition, Mauna Kea rises 9 km from the sea floor, making it the tallest. Not much good it helps this discussion though :slight_smile:

I’ll add to what Antonius Block said.

My copy of “California Hiking” lists the top two viewpoints on Earth, in terms of how much total area you can see, as the peak of Mount Kilimanjaro (#1) followed by Mount Diablo right here in the East Bay as #2.

On a clear day, with good eyesight, people have seen Mount Shasta, the Farralon Islands and parts of Yosemite. Pretty damn far.

…and on further reading I see Antonius’ link mentions the exact same stuff…

I did just that driving west through Kansas some years ago. I remembered reading as a kid how the pioneers traveling west could see Pike’s Peak, the tallest mountain in the Front Range, from some distance away. 70 is mostly level but every few miles you climb a short little grade as you get further from the Mississippi River basin. Every time I topped one of those rises, I’d scan the horizon until I was finally rewarded by a white blip in the haze. I memorized the mile marker, then measued the diatance on a map later in a rest stop. It was 90 miles.

I imagined those poor suckers pointing and yelling, “Look! Look! It’s Pike’s Peak. We’re almost to the Rockies!” At ten miles a day it was more than a week before they got there.


I had considered mentioning the “#2 after Kilimanjaro in area of view” claim for Mount Diablo, but I’ve always been rather sceptical of its veracity. After all, Mount Diablo is only 3849 feet high, positively Lilliputian compared to the great mountains of the world. This guy here presents some pretty compelling arguments debunking the claim, and he concludes that it was probably just made up by local boosters.

I’ve seen Mount Diablo from the Farallon Islands even when the air wasn’t particularly clear, but that’s only 61 miles. If it’s true that one can see Mount Shasta from Mount Diablo (245 miles as I posted earlier), that’s more a function of how tall (14162 ft) and distinctive Shasta is. I’ll bet that it’s easier to identify Shasta from Diablo than vice versa.

My son did an extra credit problem in Geomety (with my idea)…

Being in Southern California, the tallest mountain is San Gorgonio (~11,500’). The problem I presented my son for extra credit is: Can you see Catalina Island from San Gorgonio? First we determined the statute miles between the peak and closest point on the island relative to the peak. Turned out it was about 106(?) miles using a distance calculator from the internet.

Next we applied the equation:
A square of tangent (line of sight) line segment is equal to a product of a secant line segment (earth’s diameter) by the secant line external part (elevation of San Gorgonio).

LOS[sup]2[/sup] = (ED)(ESG)

LOS[sup]2[/sup] = (7912 mi.)(2.18 mi.)

LOS[sup]2[/sup] = 17248.2 mi[sup]2[/sup]

LOS = 131.3 miles to the horizon (from peak to tangent point)

Since Catalina was 106 miles away, then it is visible from San Gorgonio (weather permitting).

If there are two peaks that are 10,500’ in elevation that are ~260 miles away, then I guess you could possibly see them by doubling the LOS distance where the midpoint must be at sea-level (and all land between is below the LOS) so there is no visual obstruction. Of course, I’m not taking atmospheric conditions in consideration, but this site does… (hey it was just a 10th grade extra credit project!)

For Mt. Everest, the LOS is 208.56 to sea-level horizon, so a theoretically you can see (w/o atmospheric conditions) a 24,600’ peak from a distance of 400 miles (if there actually is one, and the LOS is not obstructed). That’s about the limit, I’m guessing.

A more detailed approach…

Use the first illustration of this cite to understand the equation rewritten for this illustration:

BD[sup]2[/sup] = (AC)(CD)


Arrrgh. :smack:

The equation should be…

BD[sup]2[/sup] = (AD)(CD)

In other words:

The square of the LOS equals the product of the WHOLE secant (earth’s diameter PLUS Peak Elevation) times the Peak Elevation itself…


LOS[sup]2[/sup] = (7912 mi. + 2.18 mi.)(2.18 mi.)

LOS[sup]2[/sup] = 17252.9 mi.[sup]2[/sup]

LOS = 131.35 miles to the horizon (from peak to tangent point)

A very minor nitpick, but I didn’t want to give you the wrong equation… :smack: :smack: :smack: