What exists beyond Earth? Over six lectures presented in 1977, American astronomer and cosmologist Carl Sagan explores the vast expanse of space that surrounds the third planet from the Sun.

Life on Earth

Where at first we could only discern the size of our planet and some knowledge of its atmosphere and configuration, the evolution of planetary exploration has revealed not only intricate details of Earth’s climate and geology, but a multitude of stars and planets besides our own.  

Beginning with a closer look at the world we inhabit, Sagan explores of the diversity of life on our own planet and the building blocks behind it, before questioning whether the same organic chemistry is occurring on planets in the outer solar system.

The Red Planet

In Lecture Three onwards Sagan takes a closer look at our neighbouring planet, Mars. From early interpretations of terrestrial life on its surface to the surprising discoveries made by NASA’s Viking Program, the Red Planet has become the focus of efforts to discern whether intelligent life exists elsewhere in the universe.   

When Sagan delivered his lectures in the late 1970s, NASA had only just begun its Voyager program to the furthest planets in our solar system and no extra-solar planets were known to exist. Now, over three decades later, astronomers are looking at planets that lie beyond our solar system to ask the very same question we pondered over Mars: is there life out there?

Media Gallery

  • Carl Sagan at the Planetary Society

    Bruce Murray, Harry Ashmore, Carl Sagan and Louis Friedman (left to right), the founders of The Planetary Society at the time of signing the papers formally incorporating the organisation.

    Image: NASA

  • Carl Sagan

    Carl Sagan with a model of the Viking lander

    Image: NASA

CHRISTMAS LECTURES 1977: The Planets

A classic lecture series exploring the Solar System. By Professor Carl Sagan

Carl Sagan

Image: NASA