Horizon Distance Calculator
Estimate how far the horizon is from your viewpoint. Choose a height and compare Earth, Moon, and Mars (approximate, ignores refraction).
Distance to the horizon
Formula used
d ≈ √(2Rh + h²), where R is radius and h is observer height.
If the object also has height, its visible distance increases (you can add both horizon distances).
How we calculate
We use the geometric horizon formula for a sphere: d = √(2Rh + h²). For small h compared to R, this is close to d ≈ √(2Rh).