What is the current primary activity of the SETI program?

• A. Sending messages to distant civilizations
• B. Scanning exoplanet atmospheres for biosignatures
• C. Listening for signals broadcast by advanced civilizations
• D. Visiting nearby star systems with probes

Answer: (C)

The main idea being tested is what SETI does now to look for intelligent life: it mostly involves listening for signals. SETI uses radio telescopes and other instruments to scan large portions of the sky across wide frequency ranges, searching for unusual, non-natural signals that might indicate an intentional or technology-driven source from an advanced civilization. Modern efforts like Breakthrough Listen exemplify this passive-search approach, expanding the search to both radio and optical wavelengths, but they don’t rely on sending messages or probing planets directly.

Sending messages to distant civilizations is a concept some people discuss (METI), but it isn’t the ongoing focus of SETI today. Scanning exoplanet atmospheres for biosignatures belongs to astrobiology and exoplanet science—looking for signs of life, but not necessarily intelligent life, and not the core aim of SETI. Visiting nearby star systems with probes is exploration rather than SETI, constrained by our current technology and mission priorities.

So the current primary activity is listening for signals broadcast by advanced civilizations.