Why are ratio telescopes instead of optical telescopes used to determine the structure of the milky way galaxy?

Ratio telescopes, often referred to as radio telescopes, are used to study the structure of the Milky Way galaxy because they can detect radio waves emitted by celestial objects, allowing for observations through interstellar dust that obscures optical wavelengths. This capability enables astronomers to map the distribution of hydrogen gas and other components of the galaxy, revealing its spiral structure and dynamics. Additionally, radio telescopes can capture data from various wavelengths, providing a more comprehensive understanding of the galaxy's morphology and behavior.