Looking back: The Sky at Night
15 May 1974
On the 15 May 1974 episode, Patrick Moore spoke with US astronomer Carl Sagan about the many investigative strands when looking for alien life.
“One is laboratory work on the question of the origin of life, making the molecules which [would]… lead eventually to us,” said Sagan. Today, lab work investigates how molecules present at our planet’s birth could grow into the complex chemistry seen today.
“Second is a study of the organic chemistry in places like Jupiter, comets and the interstellar medium,” said Sagan. “It’s remarkable that the molecules of life are littering the cosmos.” Organics have been found on Mars, moons, asteroids, comets, even Pluto, as well as the planet-forming discs around young stars.
“Thirdly, the exploration of neighbouring planets, in particular for life-related compounds,” said Sagan. Much research in this field has focused on Mars, culminating in the Perseverance rover which will return samples to Earth in the 2030s. Now interest is turning to the icy moons, with planned missions to Europa and Titan.
“Then there’s the serious work – longterm, patient, cautious – of investigating other stars for potential signals being sent our way,” said Sagan, who founded the SETI Institute which searches for signals, though none have been found.
One area Sagan didn’t consider was the study of exoplanets. The first wouldn’t be discovered for 15 years, but they’re now key to the search. Turn to page 68 for more on finding alien life.