Point source

A point source is a single identifiable localized source of something. A point source has a negligible extent, distinguishing it from other source geometries. Sources are called point sources because, in <a href="/facts/Mathematical_model/CGhyuxgz">mathematical modeling</a>, these sources can usually be approximated as a mathematical <a href="/facts/Point_(geometry)/6YPAvX2a">point</a> to simplify analysis.
The actual source need not be physically small if its size is negligible relative to other length scales in the problem. For example, in <a href="/facts/Astronomy/0ArJVM1p">astronomy</a>, <a href="/facts/Star/euBFuo07">stars</a> are routinely treated as point sources, even though they are in actuality much larger than the <a href="/facts/Earth/HLLmDfj0">Earth</a>.
In <a href="/facts/Three-dimensional_space/KAqKWUbS">three dimensions</a>, the density of something leaving a point source decreases in proportion to the <a href="/facts/Inverse_square/DxG4T15l">inverse square</a> of the <a href="/facts/Distance/hbXlaEFk">distance</a> from the source, if the distribution is <a href="/facts/Isotropic/mc3QEY2x">isotropic</a>, and there is no <a href="/facts/Absorption_(electromagnetic_radiation)/xBYKt7yS">absorption</a> or other loss.

Point source open-in-new

Point source