Carl Sagan’s birthday was Nov. 9, and he would have been 84 years old this year. Sagan died in 1996, so he missed the first launch of SpaceX’s Falcon 9 rocket and Curiosity’s Mars landing, among other notable moments in space exploration.

Since his death was more than 20 years ago, most millennials are probably only dimly aware of Sagan, except that he was the previous host of “Cosmos” before Neil deGrasse Tyson. But Sagan was more than a TV presence; he published over 600 scientific papers and was the co-author or editor of more than 20 books, according to Google Scholar: He was a catalyst for many advances in space research.

Sagan’s legacy cajoles the scientific community to take the possibility of life on other planets seriously. He reasoned that life must be abundant in the universe because there are so many stars, and the sun is a typical star, according to a New York Times obituary. While that vision hasn’t come to pass yet, Sagan’s influence on the topic is considerable. Below are his three most notable contributions to science.

The “Pale Blue Dot”

In 1990, when Voyager I was on the cusp of leaving our solar system, hurtling towards interstellar space, it was Sagan’s idea to turn the spacecraft’s cameras back toward the home planet so viewers could gain perspective. The Pale Blue Dot, as the photo is famously known, showed an infinitesimal Earth almost 4 billion miles away.

“That’s here,” Sagan said, in an account in the Express. “That’s home. That’s us. On it, everyone you love, everyone you know, everyone you have ever heard of, every human being who ever was, lived out their lives…[E]very king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every revered teacher of morals, every corrupt politician, every superstar, every supreme leader, every saint and sinner in the history of our species lived there–on a mote of dust suspended in a sunbeam.”

Sagan’s imprint — a “golden record” with recordings of sights and sounds from Earth — remains on the Voyager I probes 41 years later, recounted NPR. Sagan and a team of scientists were tasked to come up with sounds to represent the world. The record, which is duplicated for each probe, contains 115 images plus sounds of ocean, wind, thunder and birds. But mostly it contains music and languages representing the entire earth. From Solomon Island pan pipes to Chuck Berry, it was meant to be a sign of peace and goodwill to extraterrestrial beings.

Missions to Mars, Venus and Jupiter

Besides his influence on the details of the Voyager I, Sagan designed and managed missions to Mars, Venus and Jupiter helping propel advances in space research. In 1960, as a doctoral student he uncovered the mystery of Venus’ high surface temperature, concluding it was a massive greenhouse effect that made its surface inhospitable to any forms of life at over 600 degrees Fahrenheit, according to NPR. But Sagan said his research still did not rule out the possibility of life in the planet’s atmosphere. That hope guided recent new research that points to possible life in Venus’ clouds, according to Popular Mechanics.

As Wired reported, in his role as a visiting scientist at the Jet Propulsion Laboratory in Pasadena, California, Sagan helped design and manage various missions to space.

Educating the Public About Space

As NASA recalls, Sagan was often described as “the scientist who made the Universe clearer to the ordinary person.” He helped to popularize science through the writing of hundreds of articles and over two dozen books. He won a Pulitzer Prize in 1975 for his book “The Dragons of Eden.”

Sagan’s television series “Cosmos” was one of the most-watched shows in public television history. More than 500 million people in 60 different countries tuned in, according to Slate. As a result, Sagan became a celebrity and even launched the catchphrase “billions and billions,” which How Stuff Works reported Sagan never actually said but is rather based on Johnny Carson’s imitation of Sagan.

Carl Sagan’s birthday was a reminder of his legacy. Variety has reported that Warner Bros. is planning a Carl Sagan biopic that will tell his story and perhaps even inspire a new generation of viewers.