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The cylindrical radius ρ of the point P is given by = + and its distances to the foci in the plane defined by φ is given by = (+) + = + The remaining coordinates μ and ν can be calculated from the equations cosh μ = d 1 + d 2 2 a cos ν = d 1 − d 2 2 a {\displaystyle {\begin{aligned}\cosh \mu &={\frac {d_{1}+d_{2}}{2a}}\\\cos \nu ...
The plate scale of a telescope connects the angular separation of an object with the linear separation of its image at the focal plane. If focal length f {\displaystyle f} is measured in mm, the plate scale in radians per mm is given by angular separation θ and the linear separation of the image at the focal plane s , or by simply the focal ...
Prolate spheroidal coordinates μ and ν for a = 1.The lines of equal values of μ and ν are shown on the xz-plane, i.e. for φ = 0.The surfaces of constant μ and ν are obtained by rotation about the z-axis, so that the diagram is valid for any plane containing the z-axis: i.e. for any φ.
A scale factor is usually a decimal which scales, or multiplies, some quantity. In the equation y = Cx, C is the scale factor for x. C is also the coefficient of x, and may be called the constant of proportionality of y to x. For example, doubling distances corresponds to a scale factor of two for distance, while cutting a cake in half results ...
If k = −1, then (loosely speaking) one can say that i · a is the radius of curvature of the universe. a is the scale factor which is taken to be 1 at the present time. k is the current spatial curvature (when a = 1). If the shape of the universe is hyperspherical and R t is the radius of curvature (R 0 at the present), then a = R t / R 0
A scale factor, (conventionally called the speed-of-light) relates distances measured in space to distances measured in time. The magnitude of this scale factor (nearly 300,000 kilometres or 190,000 miles in space being equivalent to one second in time), along with the fact that spacetime is a manifold, implies that at ordinary, non ...
The radial scale is r′(d) and the transverse scale r(d)/(R sin d / R ) where R is the radius of the Earth. Some azimuthal projections are true perspective projections ; that is, they can be constructed mechanically, projecting the surface of the Earth by extending lines from a point of perspective (along an infinite line through the ...
(The Sun's diameter is 400 times as large and its distance also; the Sun is 200,000 to 500,000 times as bright as the full Moon (figures vary), corresponding to an angular diameter ratio of 450 to 700, so a celestial body with a diameter of 2.5–4″ and the same brightness per unit solid angle would have the same brightness as the full Moon.)