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Why Your Dog Hates Postal Workers

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It might seem like a TV trope, but there’s actual science at play here. It works like this: The sight of a uniformed stranger carrying a big, goofy bag drives Fido to get excited and bark. When the letter carrier leaves to visit the next mailbox on his or her appointed rounds, the dog mistakenly believes yelping drove them away. So the next day, it barks again. And it works again! And again.

It’s a case of operant conditioning: The dog acts that way because the behavior is reinforced and rewarded—the postal service is unintentionally training your dog to go bonkers. And it’s a huge issue. Aggressive dogs are such a constant (and costly) problem that the USPS recommends all postal workers carry a full can of dog pepper spray, which stains the “dog menace” yellow so it can be identified.

To alert mail carriers of toothy pooches along a route, the agency issues bright orange “Dog Warning Cards,” which reveal the dog’s address, breed, and name. But even that’s not enough. The USPS still releases a yearly dog attack report, which recently revealed that hounds took a bite out of 5767 postal workers last year. That’s nearly 16 attacks a day. With that in mind, maybe you should throw your mail carrier a bone.


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Why Are Glaciers Blue?
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The bright azure blue sported by many glaciers is one of nature's most stunning hues. But how does it happen, when the snow we see is usually white? As Joe Hanson of It's Okay to Be Smart explains in the video below, the snow and ice we see mostly looks white, cloudy, or clear because all of the visible light striking its surface is reflected back to us. But glaciers have a totally different structure—their many layers of tightly compressed snow means light has to travel much further, and is scattered many times throughout the depths. As the light bounces around, the light at the red and yellow end of the spectrum gets absorbed thanks to the vibrations of the water molecules inside the ice, leaving only blue and green light behind. For the details of exactly why that happens, check out Hanson's trip to Alaska's beautiful (and endangered) Mendenhall Glacier below.

[h/t The Kid Should See This]

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New Jersey Is Now Home to the Western Hemisphere's Largest Planetarium

Space-loving tourists often travel to Manhattan to visit Hayden Planetarium at the American Museum of Natural History. But starting December 9, they’ll be able to get their fill of stars and planets in nearby Jersey City. As Astronomy reports, New Jersey’s second-most-populous city is now home to the largest planetarium in the Western Hemisphere, and the fourth largest in the world.

The Liberty Science Center in Jersey City, an interactive science museum in Liberty State Park, opened in 1993. It’s home to 12 museum exhibition halls, aquariums, a live animal collection, and an IMAX dome theater. On July 31, 2017, the theater was closed for extensive renovations, thanks to a $5 million gift from an altruistic former high school teacher-turned-philanthropist, Jennifer Chalsty, who’s served as a science center trustee since 2004.

Renamed the Jennifer Chalsty Planetarium, the IMAX theater received a digital upgrade and a brand-new screen, and was provided with the requisite technology to serve as a planetarium. The theater’s dome is 60 feet high, with a diameter of 89 feet, and its 10-projector system broadcasts onto a 12,345-square-foot domed screen.

There are only three planetariums in the world that are larger than the Jennifer Chalsty Planetarium, and they’re all located in China and Japan. “You can fit any other planetarium in the Western Hemisphere inside the Jennifer Chalsty Planetarium,” said Paul Hoffman, the science center's president and CEO, in a press release. “Add in the state-of-the-art technology and you have a spectacular unique theater like none other in the world. Visitors will be able to fly through the universe, experience the grandness and vastness of space, roam planetary surfaces, navigate asteroid fields, and watch the latest full-dome movies."

[h/t Astronomy]

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