The Cosmic Distance Scale

The Cosmic Distance Scale is a series of methods astronomers use to measure the universe's vast distances. Since we can't reach most objects directly, they rely on "rulers" like Cepheid variable stars, whose brightness tells us their distance, or galaxy brightness and shape. By combining these methods, scientists can accurately determine how far away stars, galaxies, and other cosmic objects are, helping us understand the size, structure, and expansion of the universe. It’s a step-by-step approach that builds from nearby objects to distant galaxies, creating a "ladder" of distance measurements.