How did scientist know how far the other star ,sun and galaxy is ?
There are three methods (at least) that are used to determine astronomical distances: 1. Relatively nearby stars within our own galaxy can be measured using the parallax shift method, which is a direct form of distance measurement using triangulation based on the length from one side of earth’s orbit to the other. 2. More distant objects, like nearby galaxies, can be measured by determining the intensity of a certain type of star within the galaxy. These stars, known as Cepheid Variables, possess a known and predictable absolute intensity as a function of their frequency of light variation. By measuring the frequency (or period) of variation, we know with reasonable accuracy how far away they are. 3. The most distant galaxies are measured by using the Doppler shift within the spectrum of the light arriving from the object. By measuring the Doppler shift, we can determine how quickly the object is receding from us. Then, by comparison to the surrounding universe (using an approximate Hu
