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Climate denial ... creationism ... doomsday predictions ... vaccination warnings: It's all in a day's debunking for Phil Plait, the astronomer and skeptic who weighs in on all sorts of pseudo-science.

Plait, 48, started out as a researcher delving into supernovae, gamma-ray bursts and other mysteries of the universe. But that began to change when he wrote a book titled "Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing 'Hoax.'"

Over the years, he has devoted more and more time to scientific reality checks — in a follow-up book titled "Death From the Skies!" as well as his "Bad Universe" TV documentary series and the Bad Astronomy blog, now in its ninth year.

Bad Astronomy is about much, much more than bad astronomy. Plait takes on those who claim that global warming doesn't exist, that "creation science" needs to be taught in biology class or that kids shouldn't be vaccinated. For a time, he even served as the president of the James Randi Educational Foundation, which takes aim at all sorts of pseudo-scientific silliness.

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So how does Plait's B.S. detector work? Here are some pointers from the pro:

Find out who's making the claim: Certain people have a history of promulgating B.S., and if you come across the latest claim from such people, your skeptical antennae should perk up. "That doesn't mean they're wrong, but it's not a bad place to start," Plait said.



Certain people have a history of promulgating B.S., and if you come across the latest claim from such people, your skeptical antennae should perk up. "That doesn't mean they're wrong, but it's not a bad place to start," Plait said. Build a baloney detection kit: Before you get swept up in an artfully crafted argument, apply some scientific principles to the claims. As the late astronomer Carl Sagan said, "Extraordinary claims require extraordinary evidence." Sagan's own baloney detection kit is a good place to start. (The RationalWiki has boiled down his essay to hit the bullet points.)



Before you get swept up in an artfully crafted argument, apply some scientific principles to the claims. As the late astronomer Carl Sagan said, "Extraordinary claims require extraordinary evidence." Sagan's own baloney detection kit is a good place to start. (The RationalWiki has boiled down his essay to hit the bullet points.) Find out what other folks are saying: Check to see what your trusted sources have to say about a controversial claim. Of course Plait hopes that Bad Astronomy is one of those trusted sources — but he adds a caveat: "Don't trust me. I make mistakes, too. Pay attention to what other people are saying, weigh the facts, and try not to be biased."



Here are a few of Plait's trusted sources on contentious topics:

Bad Astronomy's Phil Plait takes aim at pseudo-science. Google

Plait said he isn't able to engage with his fans and foes as much as he did in the early days, but when it comes to debating science vs. pseudo-science, he tries to obey Wheaton's Law (basically, "don't be a jerk"). He also follows Patrick Swayze's advice from the movie "Roadhouse": "Be nice ... until it's time to not be nice."

Plait promised to be nice during our online chat on "Virtually Speaking Science," a talk show that airs at 8 p.m. ET Wednesday via Blog Talk Radio and in the Exploratorium's virtual auditorium in Second Life. Join the virtual audience, listen to the hourlong show live online, or download the podcast anytime via Blog Talk Radio or iTunes. You can send in questions via Twitter, using the hashtag #askVS. And while you're at it, check out these archived shows from "Virtually Speaking Science":

In addition to Bad Astronomy, Phil Plait's projects include the Boulder Science Festival, which takes place on Oct. 12 and 13 at the Millennium Hotel in Boulder, Colo.; and Science Getaways, which offers science-themed travel opportunities. On Wednesday, Plait announced that Space Ranch 2014 is scheduled for Feb. 27-March 3 at the Tanque Verde Ranch in Tucson, Ariz.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding +Alan Boyle to your Google+ circles. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.