As Jon Stewart's tenure as host of "The Daily Show" comes to a close, with the final episode airing tonight, it's worth noting the times the satirical show served up science to its viewers.
In his 16 years as host, Stewart focused on the media and government. But he also gave scientists a platform to discuss their thoughts on topics as diverse as the emotions of chimpanzees and the number of stars in the sky.
Stewart's curiosity seemed to reflect that of his audience, and his talks with scientists never failed to spur lively conversations. Here are seven times "The Daily Show" shined its limelight on science.
1. Neil deGrasse Tyson
Astrophysicist and science-communicator extraordinaire Neil deGrasse Tyson visited The Daily Show many times. Stewart was such a fan that he once asked Tyson, on an episode that aired in July 2007, "Why is it when you talk about science, I get horny?"
Tyson had come to the show to promote his program "NOVA ScienceNOW," and explained ongoing research on the bacteria called extremophiles, which are organisms with a taste for danger in the form of scorching temperatures, frigid climates, toxic air, and other intense conditions. It's possible that these organisms hitch rides on meteors and travel around in the universe, Tyson told Stewart.
The scientist also stressed the enormity of the universe, saying there are more stars in space than there are grains of sand on Earth.
During Tyson's most recent appearance, in April 2015, he talked about his excitement that "there is a culture that thinks about science, and likes science." Tyson said, "We only enter the future on the intellectual capital brought to this world by the geekosphere."
2. Week of Evolution Schmevolution
During one week in September 2005, Stewart devoted a segment each night to evolution, calling it "one of nature's most controversial topics."
At the time, the Dover Area School District in Dover, Pennsylvania, had recently voted to allow the teaching in science classes of religious ideas about the origin of life, calling it "intelligent design."
In segments called "Evolution Schmevolution," Stewart asked his audience, "Are we characters in a dubious fairy tale written thousands of years ago, in the depths of human ignorance? Or random globs of cells who got a little luckier than s--- that grows on our shower tiles?"
Daily Show correspondent Ed Helms went on a "Heritage Tour," to visit various battlegrounds of the evolutionary war. To get the real story, Helms traveled to Dayton, Tennessee, to visit the site of the Scopes Monkey Trial; the Bronx Zoo, to learn how closely humans are related to chimps (they share 98.5 percent of the same genes); and Hooters, to understand how species adapt special characteristics (in Hooters' case, voluptuous breasts) to proliferate against all odds.
Eventually, the school district's decision lost its court case, with a Pennsylvania court finding that teaching religious ideas in public schools violated the separation of church and state as outlined in the First Amendment of the Constitution.
3. Elon Musk
Elon Musk, CEO of SpaceX and Tesla, appeared on The Daily Show in April 2012. Stewart commended Musk for launching a rocket on a spaceship into orbit and returning it to Earth, saying, "This is what I know about science: The four entities that have done that are the United States, China, the Soviet Union and Elon Musk."
Musk said he had to fund his SpaceX venture with the money he made by founding and selling PayPal, because "rockets are pretty far out of the comfort zone of most venture capitalists."
When SpaceX was a younger company, it launched rockets "from a remote tropical island," Musk said, though now the company launches from Cape Canaveral, Florida.
Musk said that one day he hopes there will be self-sustaining human civilizations on multiple planets, starting with Mars. He said multi-planetary populations would be needed to continue human existence, but also to inspire people. It's important to have things that are exciting and transcend current human problems, Musk said.
4. Burn Noticed
Stewart's coverage of New York City's Climate March in September 2014 was especially biting. He asked, "Do we really need a march to raise awareness about global warming?" But then he quickly answered yes, saying the idea that climate change is happening is accepted everywhere but the United States House of Representatives Committee on Science, Space and Technology.
Stewart aired clips of politicians meeting to discuss President Obama's plan to shrink carbon dioxide output in the United States. In one video, Texas Representative Steve Stockman asked a question about the wobble of Earth's axis and its contribution to climate change, to which Stewart, pretending to jump right on Stockman's bandwagon, snarked, "What's up, scientists? Global wobbling, bitches!"
But John Holdren, senior advisor to the president on science and technology issues, explained that global wobbling occurs on timescales of 22,000; 44,000; and 100,000 years, so that wobbling imparts a only tiny effect on climate change models, which cover only 100 years. After Holdren's explanation, Stewart faked shock and side-whispered, "I didn't know we'd be talking to an actual scientist."
When Representative Larry Bucshon from Indiana asked how melting ice can raise sea level, since melting ice in a glass of water doesn't overflow the water, Stewart exasperatedly asked, "How far back to the elementary school core curriculum do we have to go?!" He then brought out a cup of water and began to patronize Bucshon with a demonstration of what happens when ice on land — "you know, the part where water isn't" — melts and enters the water. The result? A very wet desk.
5. Jane Goodall
Jane Goodall, a primatologist famous for her work with chimpanzees, appeared on The Daily Show twice, first in November of 2009 to promote her book, "Hope for Animals and Their World" (Grand Central Publishing, 2009). On that visit, Goodall chatted with Stewart about how similar chimp emotions are to human emotions. She appeared for a second time in April of 2012, as a spokesperson for Disney's documentary "Chimpanzee" (Disneynature, 2012).
In her more recent appearance, Goodall said that seeing chimps express both the bright and dark sides of human emotions made her think, "Gosh, they're really like people." Stewart commented that humans and chimps share 98 percent of their genes, and then quipped, "Although if you saw me with my shirt off, you'd say 99.9."
6. Pope-ular Science
In June 2015, Stewart covered Pope Francis' encyclical that urged action on climate change along with the reactions of U.S. politicians to the Pope's statement. He showed a clip of Senator Jim Inhofe from Oklahoma, a longtime denier of the reality of human-induced climate change, who said he doesn't consider the pope an authority on environmental issues.
Stewart also shared a quote from Rick Santorum, a Republican candidate in the 2016 presidential race, who said, "The church has gotten it wrong a few times on science, and I think that we probably are better off leaving science to the scientists and focusing on what we're really good at, which is theology and morality."
Stewart pointed out that scientists have an overwhelming consensus on climate change, but suggested that to best reach Republican voters, the politicians might want to sell their viewpoint as, "taking a stand for preserving traditional sea levels," because that might be more persuasive.
7. Richard Dawkins
Richard Dawkins, famed evolutionary biologist and atheist, came on the show in September 2013 to promote his book, "An Appetite for Wonder: The Making of a Scientist" (Ecco, 2013). Stewart asked Dawkins about the possibility of an afterlife, and whether there could be "something beyond us," that would allow humans to maintain something of their consciousness after death. Dawkins said that from a scientific point of view, belief in an afterlife isn't logical.
"I believe in the scientific method, but I know that faith and science are both controlled by the same flawed mechanism, which is us," Stewart said, adding that he doesn't always trust humans.
Dawkins explained that the origin of life was a gradual process, and that the chances of it beginning were extremely improbable. He said there could be a billion planets with life, a fraction of the number of planets in space, but the habitable planets could be so spread out that they likely will never know of each other.
"This is so cool to think about," Stewart said.