Stars are only points of light in the sky. we cannot see how big they are, nor any surface features that might indicate they are sun-like. discuss the many observations that we can make that tell us what stars are. these observations might include distance, various color and spectrum measurements, orbital measurements of binary stars, and/or stellar eclipses, among others. the fundamental properties of stars as observable objects are mass, radius, luminosity, surface temperature, element composition, and rotation, as well as distance. how do we determine these properties?