Sagan Talk Brings Science Down to Earth

In a speech that ricocheted between poetic reverence for the complexities of the universe and edgy disgust with opportunistic politicians, Carl Sagan showed why he has become perhaps the most popular scientist of his time.

By turns enthusiastic, emphatic, patient and hopeful, Sagan--best known to millions of television viewers as the host of the science series “Cosmos”--skipped through millennia and searched deep space in a 90-minute talk for supporters of the Discovery Museum of Orange County.

Sagan’s after-dinner speech and slide show hushed a black-tie group to respectful silence on Thursday at the Westin South Coast Plaza hotel in Costa Mesa. Without using notes, the astronomer spoke with the clarity born of an intellectual life ruled by logic. In the scientific method of thinking, he told listeners, “everything has to be checked. You don’t take things on faith. And arguments from authority are no good. You have to be courageous.”

His talk was a testament to the value of that method.

Sagan began by saying he felt “lucky” to live “in the only epoch in the history of the world in which we explore the planets in the universe. Before, they were too small, too far away, and a few decades from now everything will be known. There is only this one window, this transition from ignorance to knowledge.”

Although fascinating in itself, the knowledge gained through space exploration has practical uses, Sagan said. “Every time you explore another planet, you learn something about your own.”

As a slide of the rough surface of Mars was projected onto a screen, Sagan described the physical conditions of the planet, which include the largest volcano in the solar system (three times the height of Mt. Everest), and a huge boulder “with the complex scientific name ‘Big Joe,’ ” he said.

“This doesn’t look like another world--this looks like Nevada or Utah,” Sagan said, as he studied the screen. Clearly there were no Martians around--or none of the little creatures we’ve fantasized about in movies and science fiction. But what about microbial life? Sagan asked. An analysis of soil taken from the surface of Mars provided “no convincing evidence of microbial life, no molecules based on carbon.” Carbon is the element on which all life is based.

“Why is the Martian surface so antiseptic? The only explanation that is viable is that because there is a hole in the Martian ozone layer of planet-wide proportions--in essence there is no ozone layer--ultra violet light from the sun penetrates unimpeded to the surface of the planet.

“Isn’t this a timely revelation?” Sagan asked. “Isn’t this a useful piece of information for politicians who are reluctant to commit to environmental causes?”

Timely revelations and useful pieces of information were also gleaned from studies of the climate and conditions on Venus.

With a picture of the volcanic terrain of Venus projected on the screen, Sagan described the chemical makeup of the Venusian atmosphere. “How balmy is it on Venus?” Although dense clouds shroud the planet, Sagan said, the surface of Venus is 900 degrees Fahrenheit. And the only viable explanation for that extreme temperature is “a massive carbon dioxide greenhouse effect.”

“I’m not suggesting (the temperature is so high because) generations of Venusians drove fuel-inefficient automobiles,” Sagan joked. Still, the conditions on Venus are “an excellent demonstration that greenhouse warming is real and dangerous.”

Throughout his talk, which also included a discussion of dinosaurs--”a reminder that no species is guaranteed its tenure on this planet”--Sagan repeatedly circled back to the need for greater science literacy in our society and more of the curiosity and courageous thinking that characterizes scientific method.

“This is a culture based on science and technology,” Sagan said, “yet the majority of the population knows almost nothing about science and technology. If you set out to commit national suicide, that’s how you’d design it. You’d make a society run on a system and make sure nobody understands it.”

When a final question from the audience led Sagan to a particularly vitriolic denunciation of government resistence to developing alternative energy sources, Sagan asked the audience if he could show one more slide. “I don’t want to end on such a grumpy note,” he said with a sheepish smile.

As a photo of our solar system filled the screen, Sagan said the picture had been taken by Voyager 2 “looking back over its shoulder on its way to interstellar space. A spacecraft that has left the planetary universe photographing the planet of its origin. Think about it.

“On that dot,” he said, pointing to Earth, “is every hopeful child, every couple in love, every artist, every writer, every corrupt politician. . . . If nothing else (the study of space) has provided us with a sense of our profound obligation to value and cherish and preserve that blue dot.”