Which statement best describes SETI's current activity?

• A. Launching messages to potential civilizations
• B. Conducting simulations of galactic civilizations
• C. Mapping exoplanet atmospheres
• D. Listening for signals broadcast by advanced civilizations

Answer: (D)

SETI’s ongoing activity is listening for signals broadcast by advanced civilizations. Researchers use radio telescopes and, in some programs, optical detectors to survey the sky for unusual, potentially artificial signals—narrow-band radio waves, pulsed patterns, or other modulations that stand out from natural sources. The aim is to detect technosignatures that could indicate intelligent life, while distinguishing them from natural astrophysical phenomena.

While there are discussions about sending messages to other civilizations, that isn’t the standard activity of SETI. Launching transmissions isn’t what SETI typically does. The other options describe work outside SETI’s routine focus: simulating galactic civilizations is theoretical modeling, and mapping exoplanet atmospheres is about understanding planetary habitability, not searching for intelligent signals.