How do They Measure the Diameter of a Star?
In order to measure the diameter of a star you really need three pieces of information about the star (1) distance (2) brightness (3) and color. Step 1: Scientists can figure out the total power output of the star by knowing its brightness at Earth and its distance. Step 2: Figure out the surface temperature. The universe really gave scientists a lucky break because stars are fairly predictable objects. What I mean is that, for most stars once a scientist know one property of the star they can generally figure out everything else they want to know about it. This is because stars behave like “black bodies”. This is a physics term which describes how an object of certain temperature glows at different wavelength (thus influencing its color). Most ordinary matter resembles a black body (has nothing to do with being black, it’s just terminology). You probably already have an intuitive understanding of this from your everyday experience. For example, when you heat up an object, at first it
