The easiest way is to look at a picture of the star and then look at another one taken six months later. If it has moved, that can be seen on the photo when you look at it in relation to the stars in the background of the photo. That was the first method used to find the distance to the nearest stars, and it was a big surprise to find out how far they actually were.
The answer is long and complicated, and it is too long to place here. You need to read an entire encyclopedia articles on spectroscopy and the chemical composition of intersteller objects. D.A.W.
Different chemicals emit and absorb light at various wavelengths. Astronomers can look at the wavelength of light coming from stars and determine which chemicals must be present.
Astronomers determine the surface temperatures of stars by analyzing their spectrum of light. Each star emits a unique spectrum based on its temperature which can be measured using instruments like spectrographs. By comparing the observed spectrum to known temperature profiles, astronomers can estimate the surface temperature of a star.
How close and far something is from you.
Astronomers use temperature, luminosity, size, and color to classify stars. These factors help categorize stars into different spectral types and determine their position on the Hertzsprung-Russell diagram.
Calendars and time-keeping.
It can be used to determine a Stars lifetime, its different stages.
en.wikipedia.org/wiki/Spectroscopy
The answer is long and complicated, and it is too long to place here. You need to read an entire encyclopedia articles on spectroscopy and the chemical composition of intersteller objects. D.A.W.
By finding a constant, continuous change in the coordinates of stars every year.
Rocks are to geologists as stars are to astronomers.
Different chemicals emit and absorb light at various wavelengths. Astronomers can look at the wavelength of light coming from stars and determine which chemicals must be present.
How close and far something is from you.
Astronomers determine the surface temperatures of stars by analyzing their spectrum of light. Each star emits a unique spectrum based on its temperature which can be measured using instruments like spectrographs. By comparing the observed spectrum to known temperature profiles, astronomers can estimate the surface temperature of a star.
Astronomers use the method of parallax to determine the distance to relatively close stars like Sirius. By measuring the apparent shift in position of the star as the Earth moves around the Sun, astronomers can calculate the star's distance based on trigonometry.
Stars...
Astronomers classify stars.