# Kill target is a standing torso: range distance at which a sniper must factor in Earth curvature? **URL:** \ **Category:** Factual Questions\ **Created:** [April 13, 2012, 11:12pm UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717 "2012-04-13T23:12:52Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 13, 2012, 11:12pm UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717/1 "2012-04-13T23:12:52Z")
See subject. Clearly height above or below target is part of the question. Thanks Leo No, not a need answer fast. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [April 13, 2012, 11:32pm UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717/2 "2012-04-13T23:32:30Z")
Never. If he can see the target in his scope, he already has a straight line between his gun and the target irrespective of the geometry of the earth. Earth’s gravity and rotation, he does have to take into account, though. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [April 13, 2012, 11:37pm UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717/3 "2012-04-13T23:37:55Z")
> [@leahcim](#): > > Never. If he can see the target in his scope, he already has a straight line between his gun and the target irrespective of the geometry of the earth. Earth’s gravity and rotation, he does have to take into account, though. For earths rotation effects > **[Coriolis force](https://en.wikipedia.org/wiki/Coriolis_effect)** > > In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object. In one with anticlockwise (or counterclockwise) rotation, the force acts to the right. Deflection of an object due to the Coriolis force is called the Coriolis effect. Though recognized previously by others, the mathematical expression for t... Any long range gunnery like artillery and naval guns factor this into their aim as flight times can be 30+ seconds. With rifles, the rotation of the earth is measured in thousands of an inch over even long rifle ranges. Wind is a bigger deal. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 14, 2012, 12:37am UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717/4 "2012-04-14T00:37:42Z")
> [@drachillix](#): > > For earths rotation effects > > [Coriolis force - Wikipedia](http://en.wikipedia.org/wiki/Coriolis_effect) > > Any long range gunnery like artillery and naval guns factor this into their aim as flight times can be 30+ seconds. With rifles, the rotation of the earth is measured in thousands of an inch over even long rifle ranges. Wind is a bigger deal. What a great topic. From the cite: **Bullets at high velocity through the atmosphere** Because of the rotation of the earth in relationship to ballistics, the bullet does not fly straight although it may seem like it from the shooter’s perspective. The Coriolis effect changes the trajectory of the bullet slightly to give the path of the projectile a more arched shape. This situation only occurs at extremely long distances and therefore, is used to calculate a perfect shot by today’s trained snipers. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [April 14, 2012, 12:58am UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717/5 "2012-04-14T00:58:33Z")
> [@leahcim](#): > > Never. If he can see the target in his scope, he already has a straight line between his gun and the target irrespective of the geometry of the earth. Earth’s gravity and rotation, he does have to take into account, though. Does the OP mean having to take into account that a straight line of sight is cutting a chord across the arc that would mark a constant height? ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [April 14, 2012, 1:55am UTC](https://boards.straightdope.com/t/kill-target-is-a-standing-torso-range-distance-at-which-a-sniper-must-factor-in-earth-curvature/618717/6 "2012-04-14T01:55:21Z")
Given the OP mentioned the height of the shooter is a factor, I think they’re asking about a target so far away that they dip “below the horizon”. If so the relevant formulae can be found [here](http://en.wikipedia.org/wiki/Horizon) but in short I don’t think it’s a factor for any rifle shooting (a rule of thumb from the article is that a standing person of average height can see 3 miles to the horizon, the [very longest confirmed sniper kills](http://en.wikipedia.org/wiki/Longest_recorded_sniper_kills) are at half that distance or less).