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Range (r) = approximate height of object (h) × (1000 ÷ aperture in milliradians (a)) r = h(1000/a) → where r and h are identical units, and a is in milliradians. r = h/a → where r and h are identical units, and a is in radians. The above formula functions for any system of linear measure provided r and h are calculated with the same units.
The height of the elevated point plus the Earth radius form its hypotenuse. If both the eyes and the object are raised above the reference plane, there are two right-angled triangles. If both the eyes and the object are raised above the reference plane, there are two right-angled triangles.
The comoving distance from an observer to a distant object (e.g. galaxy) can be computed by the following formula (derived using the Friedmann–Lemaître–Robertson–Walker metric): = ′ (′) where a(t′) is the scale factor, t e is the time of emission of the photons detected by the observer, t is the present time, and c is the speed of ...
For example, for an observer B with a height of h B =1.70 m standing on the ground, the horizon is D B =4.65 km away. For a tower with a height of h L =100 m, the horizon distance is D L =35.7 km. Thus an observer on a beach can see the top of the tower as long as it is not more than D BL =40.35 km away.
This reduces the shadow zone, but causes errors in distance and height measuring. In practice, to find , one must be using a value of 8.5·10 3 km for the effective Earth's radius (4/3 of it), instead of the real one. [2] So the equation becomes:
If the height h is given in feet, and the distance d in statute miles, d ≈ 1.23 ⋅ h {\displaystyle d\approx 1.23\cdot {\sqrt {h}}} R is the radius of the Earth, h is the height of the ground station, H is the height of the air station d is the line of sight distance
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs ) to Earth.
an object of diameter 1 AU (149 597 871 km) at a distance of 1 parsec (pc) Thus, the angular diameter of Earth's orbit around the Sun as viewed from a distance of 1 pc is 2″, as 1 AU is the mean radius of Earth's orbit. The angular diameter of the Sun, from a distance of one light-year, is 0.03″, and that of Earth 0.0003″. The angular ...