## Sunday, May 19, 2013

### HP35S: Distance to Horizon

HP35S Distance to Horizon

Calculator: HP 35S

Sources:
* HP 65 Navigation Pac-1 - published in 1974
* Bad Astronomy by Discovery Magazine: http://blogs.discovermagazine.com/badastronomy/2009/01/15/how-far-away-is-the-horizon/#.UYCEhMu9KSM
* Wikihow Article: http://m.wikihow.com/Calculate-the-Distance-to-the-Horizon

Input
Height above sea level, the height includes the height of the land (if any) and the distance to your eyes or eyepiece.

Output
Approximate distance to the horizon in miles.

Conversions
If you use metric, use these conversions before/after running the program:
1 m = 3.28083989501 ft
1 mi = 1.609344 km

Formula
Updated formula based on radius on Earth on average 3,959 miles.
D ≈ √(1.49922*H + H^2)
H is in feet, D is in miles

Example
H = 3 ft, D ≈ 3.67392 miles

Program
H001 LBL H
H002 ENTER
H003 ENTER
H004 1.49922
H005 *
H006 x<>y
H007 x^2
H008 +
H009 √
H010 RTN

This blog is property of Edward Shore. 2013

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