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What's So Premium About Premium Gasoline?

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They must call it premium for a reason, right? Let's find out if we're missing out on something big by not shelling out the extra 20 cents.

Knock knock. Who's there?
While you're cruising around town, your car's engine is hard at work, repeating its four-stroke cycle. The piston drops from the top of the cylinder, which fills with a mix of gasoline and air (intake stroke). The piston moves up, compressing the fuel mix (compression stroke), and the spark plug ignites the mix, pushing the piston down (power stroke) again so it can expel what's left of the spent fuel through the exhaust valves and start the process over again (exhaust stroke).

Normally, this cycle keeps repeating without a hitch. But sometimes the mix of gasoline and air loses its patience, and it ignites on its own under compression instead waiting for the spark plug. This is called "pre-ignition," but you may know it as "knocking." The results are actual pinging or knocking sounds, as well as mechanical stress on the engine as the premature ignition pushes downward on the piston before it's completed its stroke. In extreme cases, pre-ignition can burn holes in engine parts.

All in the Numbers

Gasoline is a grab bag of hydrocarbon molecules, and each one behaves differently under pressure. During the auto industry's early days, there was no way to know if a given gasoline would knock in a given engine except for filling up the tank and going for a spin. In 1927, Dr. Graham Edgar of the Ethyl Gasoline Corporation (then a division of General Motors and Standard Oil) suggested using the ratio of two hydrocarbons "“ heptane and iso-octane, which have similar volatility properties and could be produced in sufficient quantity "“ as a reference number for computing a fuel's ability to resist knock.

iStock_000006429094XSmall-gaspumps.jpgA range of test engines and test conditions have popped up over time, but today the most common are the Research Octane Number (RON, which comes from running the fuel in a test engine* and represents typical mild driving), and the Motor Octane Number (MON, which comes from running preheated fuel in a similar test engine at a higher engine speed and with variable ignition timing to represent sustained high speed, high load driving).

What we get from these tests are the numbers you see on the yellow stickers on a gas pump. These numbers, called the octane rating or anti-knock index, are the average of the two different test methods (hence the pump label (RON + MON)/2) and are the measure of the fuels' resistance to knock. If you're pumping "regular," for example, its octane rating of 87 (this varies from state to state; in higher altitude areas, "regular" is sometimes 85) means the gasoline has the same knocking properties as a mixture of 13% heptane and 87% iso-octane.

So what makes premium so great?
What's behind its higher octane rating? It won't make your car faster, give you better gas mileage or make your teeth whiter.

A higher octane rating correlates to higher activation energy, meaning that the fuel needs more energy to start a chemical reaction and is less likely to pre-ignite under compression. That's right. It's simply more resistant to knock.

Modern engines are designed with specific compression ratios "“ the ratio of the combustion chamber's volume, from its largest capacity to its smallest capacity "“ and high-performance engines usually have high compression ratios (higher compression = more power). Premium's anti-knock properties allow it to maintain grace under all that pressure.

Even if you do drive a high-performance car, regular gas isn't going to knock like a woodpecker. Most cars today have knock sensors and engine management systems that use auditory detection to actually "hear" knocking and retard the spark timing to avoid detonation and minimize knocking. If you don't have a high-performance ride, using premium if you don't need it (your manual will tell you which octane rating you should use) just gets rid of more unburned fuel during the engine's exhaust stroke, putting unnecessary stress on the emissions system and sometimes producing a rotten egg smell.

*For the curious, the test engine is a Cooperative Fuels Research (CFR) engine. It's a single-cylinder engine with a variable compression ratio and a special four-bowl carburetor that can adjust individual bowl air-fuel ratios. The only company that makes them is the Waukesha Engine Division of Dresser Industries in Waukesha, Wisconsin, and the complete Octane Rating System package costs $200,000.

If you've got a burning question that you'd like to see answered here, shoot me an email at flossymatt (at) gmail.com. Twitter users can also make nice with me and ask me questions there. Be sure to give me your name and location (and a link, if you want) so I can give you a little shout out.

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10 Memorable Neil deGrasse Tyson Quotes
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Neil deGrasse Tyson is America's preeminent badass astrophysicist. He's a passionate advocate for science, NASA, and education. He's also well-known for a little incident involving Pluto. And the man holds nearly 20 honorary doctorates (in addition to his real one). In honor of his 59th birthday, here are 10 of our favorite Neil deGrasse Tyson quotes.

1. ON SCIENCE

"The good thing about science is that it's true whether or not you believe in it."
—From Real Time with Bill Maher.

2. ON NASA FUNDING

"As a fraction of your tax dollar today, what is the total cost of all spaceborne telescopes, planetary probes, the rovers on Mars, the International Space Station, the space shuttle, telescopes yet to orbit, and missions yet to fly?' Answer: one-half of one percent of each tax dollar. Half a penny. I’d prefer it were more: perhaps two cents on the dollar. Even during the storied Apollo era, peak NASA spending amounted to little more than four cents on the tax dollar." 
—From Space Chronicles

3. ON GOD AND HURRICANES

"Once upon a time, people identified the god Neptune as the source of storms at sea. Today we call these storms hurricanes ... The only people who still call hurricanes acts of God are the people who write insurance forms."
—From Death by Black Hole

4. ON THE BENEFITS OF TECHNOLOGY INVENTED FOR USE IN SPACE

"Countless women are alive today because of ideas stimulated by a design flaw in the Hubble Space Telescope." (Editor's note: technology used to repair the Hubble Space Telescope's optical problems led to improved technology for breast cancer detection.)
—From Space Chronicles

5. ON THE DEMOTION OF PLUTO FROM PLANET STATUS 

PBS

"I knew Pluto was popular among elementary schoolkids, but I had no idea they would mobilize into a 'Save Pluto' campaign. I now have a drawer full of hate letters from hundreds of elementary schoolchildren (with supportive cover letters from their science teachers) pleading with me to reverse my stance on Pluto. The file includes a photograph of the entire third grade of a school posing on their front steps and holding up a banner proclaiming, 'Dr. Tyson—Pluto is a Planet!'"
—From The Sky Is Not the Limit

6. ON JAMES CAMERON'S TITANIC

"In [Titanic], the stars above the ship bear no correspondence to any constellations in a real sky. Worse yet, while the heroine bobs ... we are treated to her view of this Hollywood sky—one where the stars on the right half of the scene trace the mirror image of the stars in the left half. How lazy can you get?"
—From Death by Black Hole

7. ON DEATH BY ASTEROID

"On Friday the 13th, April 2029, an asteroid large enough to fill the Rose Bowl as though it were an egg cup will fly so close to Earth that it will dip below the altitude of our communication satellites. We did not name this asteroid Bambi. Instead, we named it Apophis, after the Egyptian god of darkness and death."
—From Space Chronicles

8. ON THE MOTIVATIONS BEHIND AMERICA'S MOONSHOT

"[L]et us not fool ourselves into thinking we went to the Moon because we are pioneers, or discoverers, or adventurers. We went to the Moon because it was the militaristically expedient thing to do."
—From The Sky Is Not the Limit

9. ON INTELLIGENT LIFE (OR THE LACK THEREOF)

Perhaps we've never been visited by aliens because they have looked upon Earth and decided there's no sign of intelligent life.
Read more at: https://www.brainyquote.com/quotes/quotes/n/neildegras615117.html
Perhaps we've never been visited by aliens because they have looked upon Earth and decided there's no sign of intelligent life.
Read more at: https://www.brainyquote.com/quotes/quotes/n/neildegras615117.html

"Perhaps we've never been visited by aliens because they have looked upon Earth and decided there's no sign of intelligent life."

10. PRACTICAL ADVICE IN THE EVENT OF ALIEN CONTACT 

A still from Steven Spielberg's E.T. the Extra-Terrestrial
Universal Studios
"[I]f an alien lands on your front lawn and extends an appendage as a gesture of greeting, before you get friendly, toss it an eightball. If the appendage explodes, then the alien was probably made of antimatter. If not, then you can proceed to take it to your leader."
—From Death by Black Hole
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40 Fun Facts About Sesame Street
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Now in its 47th season, Sesame Street is one of television's most iconic programs—and it's not just for kids. We're big fans of the Street, and to prove it, here are some of our favorite Sesame facts from previous stories and our Amazing Fact Generator.

Sesame Workshop

1. Oscar the Grouch used to be orange. Jim Henson decided to make him green before season two.

2. How did Oscar explain the color change? He said he went on vacation to the very damp Swamp Mushy Muddy and turned green overnight.

3. During a 2004 episode, Cookie Monster said that before he started eating cookies, his name was Sid.

4. In 1980, C-3PO and R2-D2 visited Sesame Street. They played games, sang songs, and R2-D2 fell in love with a fire hydrant.

5. Mr. Snuffleupagus has a first name—Aloysius

6. Ralph Nader stopped by in 1988 and sang "a consumer advocate is a person in your neighborhood."

7. Caroll Spinney said he based Oscar's voice on a cab driver from the Bronx who brought him to the audition.

8. In 1970, Ernie reached #16 on the Billboard Hot 100 with the timeless hit "Rubber Duckie."

9. One of Count von Count's lady friends is Countess von Backwards, who's also obsessed with counting but likes to do it backwards.

10. Sesame Street made its Afghanistan debut in 2011 with Baghch-e-Simsim (Sesame Garden). Big Bird, Grover and Elmo are involved.

11. According to Muppet Wiki, Oscar the Grouch and Count von Count were minimized on Baghch-e-Simsim "due to cultural taboos against trash and vampirism."

12. Before Giancarlo Esposito was Breaking Bad's super intense Gus Fring, he played Big Bird's camp counselor Mickey in 1982.

13. Thankfully, those episodes are available on YouTube.

14. How big is Big Bird? 8'2". (Pictured with First Lady Pat Nixon.)

15. In 2002, the South African version (Takalani Sesame) added an HIV-positive Muppet named Kami.

16. Six Republicans on the House Commerce Committee wrote a letter to PBS president Pat Mitchell warning that Kami was not appropriate for American children, and reminded Mitchell that their committee controlled PBS' funding.

17. Sesame Street's resident game show host Guy Smiley was using a pseudonym. His real name was Bernie Liederkrantz.

18. Bert and Ernie have been getting questioned about their sexuality for years. Ernie himself, as performed by Steve Whitmere, has weighed in: “All that stuff about me and Bert? It’s not true. We’re both very happy, but we’re not gay,”

19. A few years later, Bert (as performed by Eric Jacobson) answered the same question by saying, “No, no. In fact, sometimes we are not even friends; he can be a pain in the neck.”

20. In the first season, both Superman and Batman appeared in short cartoons produced by Filmation. In one clip, Batman told Bert and Ernie to stop arguing and take turns choosing what’s on TV.

21. In another segment, Superman battled a giant chimp.

22. Telly was originally "Television Monster," a TV-obsessed Muppet whose eyes whirled around as he watched.

23. According to Sesame Workshop, Elmo is the only non-human to testify before Congress.

24. He lobbied for more funding for music education, so that "when Elmo goes to school, there will be the instruments to play."

25. In the early 1990s, soon after Jim Henson’s passing, a rumor circulated that Ernie would be killed off in order to teach children about death, as they'd done with Mr. Hooper.

26. According to Snopes, the rumor may have spread thanks to New Hampshire college student, Michael Tabor, who convinced his graduating class to wear “Save Ernie” beanies and sign a petition to persuade Sesame Workshop to let Ernie live.

27. By the time Tabor was corrected, the newspapers had already picked up the story.

28. Sesame Street’s Executive Producer Carol-Lynn Parente joined Sesame Workshop as a production assistant and has worked her way to the top.

29. Originally, Count von Count was more sinister. He could hypnotize and stun people.

30. According to Sesame Workshop, all Sesame Street's main Muppets have four fingers except Cookie Monster, who has five.

31. The episode with Mr. Hooper's funeral aired on Thanksgiving Day in 1983. That date was chosen because families were more likely to be together at that time, in case kids had questions or needed emotional support.

32. Mr. Hooper’s first name was Harold.

33. Big Bird sang "Bein' Green" at Jim Henson's memorial service.

34. As Chris Higgins put it, the performance was "devastating."

35. Oscar's Israeli counterpart is Moishe Oofnik, whose last name means “grouch” in Hebrew.

36. Nigeria's version of Cookie Monster eats yams. His catchphrase: "ME WANT YAM!"

37. Sesame's Roosevelt Franklin ran a school, where he spoke in scat and taught about Africa. Some parents hated him, so in 1975 he got the boot, only to inspire Gob Bluth’s racist puppet Franklin on Arrested Development 28 years later.

38. Our good friend and contributor Eddie Deezen was the voice of Donnie Dodo in the 1985 classic Follow That Bird.

39. Cookie Monster evolved from The Wheel-Stealer—a snack-pilfering puppet Jim Henson created to promote Wheels, Crowns and Flutes in the 1960s.

40. This puppet later was seen eating a computer in an IBM training film and on The Ed Sullivan Show.

Thanks to Stacy Conradt, Joe Hennes, Drew Toal, and Chris Higgins for their previous Sesame coverage!

An earlier version of this article appeared in 2012.

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