The search for extraterrestrial life: from religion to science --

Intelligence --

Where are they?: we are alone --

An abundance of worlds, an abundance of life --

Exploring new worlds: we are not lonely --

Visiting exoplanets: interstellar flight, a bridge too far --

Using nature's telescope --

Real interstellar exploration --

Comparative astrobiology --

appendix A. Interstellar messaging --

appendix B. Mayr versus Sagan, a debate on extraterrestrial intelligence --

appendix C. The search for our terrestrial intelligence.