# Is This Picture of Denali (227 Miles Away) the Furtherest Photo From The Ground?

Joined: January 1st, 1970, 12:00 am

This photo of Denali from Mount Sanford may not look like much but a website is claiming it is the longest ground to ground view ever captured by camera (227 miles).

The Sol.co.uk website has nifty panoramas showing various contenders for the title.

Many thanks to Andy Martin at cohp yahoo for the post
http://americasroof.com/wp/archives/200 ... he-ground/

Joined: April 20th, 2004, 7:19 pm
what is the theorethical farthest too points you can see from each other on planet earth?

Or, to simplify, say you're standing on a 20,000' peak. How far away would the next 20,000 ft. peak have to be before it disapears behind the horizon?

Boy I wish I could remember these details from my high school math courses.. determine the length of a a circle's tangent from the point it touches earth to at the point where it crosses a peak sitting 20,000 feet above the earth's surface at the angle that the mountain is sitting at relative to the line..

Sounds like fun. Maybe I'll look into it tomorrow when I'm recovering from dinner.

Joined: August 2nd, 2001, 8:13 pm

This photo of Denali from Mount Sanford may not look like much but a website is claiming it is the longest ground to ground view ever captured by camera (227 miles).

The Sol.co.uk website has nifty panoramas showing various contenders for the title.

Many thanks to Andy Martin at cohp yahoo for the post
http://americasroof.com/wp/archives/200 ... he-ground/
Ok, that's not a "real" number...but here is the setup:

Assume the earth is a perfect sphere (it isn't) 8,000 miles in diameter (not exactly).

Assume that Mt. Everest is 6 miles tall (it's more like 5-1/2 miles).

For a 6-mile peak on an 8,000-mile sphere, the maximum distance over which to see another 6-mile peak would be 438 and a fraction miles.

(Apologies to those of you who think metric...I did this off the top of my head with AutoCAD and just used the more familiar units for those of us who grew up in the last millennium in the USA)

So, if K2 and Everest were about 400 miles apart, you could theoretically see one from the other.

Now, Denali is under 4 miles high, so scale all that back accordingly...if there were another 20,000' peak a few hundred miles away...

Joined: July 26th, 2004, 2:40 am
what is the theorethical farthest too points you can see from each other on planet earth?

Or, to simplify, say you're standing on a 20,000' peak. How far away would the next 20,000 ft. peak have to be before it disapears behind the horizon?

Boy I wish I could remember these details from my high school math courses.. determine the length of a a circle's tangent from the point it touches earth to at the point where it crosses a peak sitting 20,000 feet above the earth's surface at the angle that the mountain is sitting at relative to the line..

Sounds like fun. Maybe I'll look into it tomorrow when I'm recovering from dinner.
The formula for the distance d to the horizon when your eyes are at height h above the surface of the earth is approximately d=sqrt(2*R*h), where R is the radius of the earth, which is about 3960 miles. (The exact formula is d=sqrt(2*R*h+h*h), but if h is small compared to R then the term h*h is negligible.) If R and h are both in miles then the result d will be in miles.

For example, if you are 6 feet tall standing at the edge of the ocean, the distance to the horizon is d=sqrt(2*3960*6/5280)=3 miles.

If you are at 20000 feet, then the distance is d=sqrt(2*3960*20000/5280)=173 miles. If there happened to be another 20000 foot mountain 346 miles away, your view line to it would just skim the horizon at the halfway point 173 miles away, and you would theoretically be just able to see it.

More generally, two observers at heights h1 and h2 can theoretically see each other if the distance between them is less than d1+d2, where d1=sqrt(2*R*h1) and d2=sqrt(2*R*h2).

This assumes that the earth is perfectly spherical (which is pretty close to being true), that light travels in a straight line (which is not exactly true when there are temperature gradients in the atmosphere), that the air is clear enough to see through (which becomes less and less true with distance), and that there is nothing else in the way (which is rarely true when there are mountains around).

Joined: July 26th, 2004, 2:40 am
The horizon distance formula d=sqrt(2*R*h) with R=3960 miles can be written as d=sqrt(1.5*h) when h is in feet and d is in miles.

Joined: November 25th, 2000, 10:31 pm

This photo of Denali from Mount Sanford may not look like much but a website is claiming it is the longest ground to ground view ever captured by camera (227 miles).

The Sol.co.uk website has nifty panoramas showing various contenders for the title.

Many thanks to Andy Martin at cohp yahoo for the post
http://americasroof.com/wp/archives/200 ... he-ground/
How high is Mt. Sanford? Is it in the Chugach?

Joined: January 1st, 1970, 12:00 am

Joined: January 20th, 2004, 6:42 pm
Ok, that's not a "real" number...but here is the setup:

Assume the earth is a perfect sphere (it isn't) 8,000 miles in diameter (not exactly).

Assume that Mt. Everest is 6 miles tall (it's more like 5-1/2 miles).

For a 6-mile peak on an 8,000-mile sphere, the maximum distance over which to see another 6-mile peak would be 438 and a fraction miles.

(Apologies to those of you who think metric...I did this off the top of my head with AutoCAD and just used the more familiar units for those of us who grew up in the last millennium in the USA)

So, if K2 and Everest were about 400 miles apart, you could theoretically see one from the other.

Now, Denali is under 4 miles high, so scale all that back accordingly...if there were another 20,000' peak a few hundred miles away...
Both Mount Logan and Muont Saint Elias are within this theoretical visible limit. Does anyone have a photograph from either of these peaks with a view toward Mount McKinley?

Joined: January 20th, 2004, 6:42 pm
How high is Mt. Sanford? Is it in the Chugach?
Mount Sanford is in the Wrangell Mountains. Its elevation is 16,237 feet.

The highest point in the Chugach Mountains is Mount Marcus Baker at an elevation of 13,176 feet.

Joined: July 26th, 2004, 2:40 am
Both Mount Logan and Muont Saint Elias are within this theoretical visible limit. Does anyone have a photograph from either of these peaks with a view toward Mount McKinley?
Using the horizon distance formula d=sqrt(1.5*h) (where h is height in feet and d is distance in miles--see "Simplification" above), the horizon distances for Denali and Mt. Logan are sqrt(1.5*20320)=175 miles and sqrt(1.5*19541)=171 miles, respectively, so to see one from the other they would have to be less than 175+171=346 miles apart. According to peakbagger.com, they are 387 miles apart, and thus invisible to each other. Mt. St. Elias is shorter and only slightly closer to Denali, so, no luck there, either.