Luminosity Distance

Luminosity distance is a way astronomers measure how far away an object like a galaxy is based on how bright it appears. Essentially, it compares the intrinsic brightness (how bright it truly is) to what we observe from Earth. If an object seems dimmer than expected, it means it’s farther away. The luminosity distance accounts for the universe’s expansion and the way light travels through space, providing a standardized way to estimate distances to distant objects in the universe. It’s a crucial tool for understanding the universe’s size, structure, and expansion rate.