How do radio telescopes study objects hidden by gas and dust in space?

Radio telescopes are essential tools for astronomy because radio waves can penetrate the vast clouds of gas and dust in space that often obscure objects from optical view. While optical telescopes are limited by these opaque regions, radio waves pass through them with little distortion, allowing astronomers to obtain a much clearer picture of stars and galaxies.12

Radio telescopes study these hidden objects by detecting and interpreting radio-frequency energy emitted or reflected by various celestial sources. Key methods include:12

• Spectral Line Observations: Astronomers use sensitive spectrometers to detect specific emission lines, such as the 21-cm radiation from cold interstellar hydrogen clouds. This allows for the mapping of galactic structures, such as spiral arms, and the study of gas motions.312
• Molecular Analysis: Radio telescopes identify complex molecules—including water, carbon monoxide, and formaldehyde—within dense dust clouds. These molecules emit radiation at specific radio wavelengths, enabling the analysis of regions where stars are actively forming.3145
• Radar Astronomy: By transmitting radio signals and measuring their reflections, astronomers can image surface features of planets, such as Venus, which are permanently hidden by thick cloud cover.31