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When the James Webb Space Telescope observes a faint point of light in the early universe, how do astronomers decide whether it is a distant galaxy or a star much closer to us? In a telescope image, both can look like small points, especially when the source is faint.
I’m curious what evidence separates early galaxies from foreground stars. Do researchers rely mainly on a spectrum and redshift, or can a star’s color and motion also help? And when the data are limited, how much uncertainty remains before an object is described as a candidate galaxy?
