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Why Does Your Nose Get Stuffy One Nostril at a Time?

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Because your nostrils split their workload. Throughout the day, they each take breaks in a process of alternating congestion and decongestion called the nasal cycle. At a given moment, if you're breathing through your nose, the lion’s share of the air is going in and out of one nostril, with a much smaller amount passing through the other. Every few hours, your autonomic nervous system, which takes care of your heart rate, digestion and other things you don’t consciously control, switches things up and your other nostril does all the heavy lifting for a little while.  The opening and closing of the two passages is done by swelling and deflating erectile tissue - the same stuff that’s at work when your reproductive organs are aroused - up in your nose.

The nasal cycle is going on all the time, but when you’re sick and really congested, the extra mucous often makes the nostril that’s on break feel much more backed up.

There are at least two good reasons why nasal cycling happens.

One, it makes our sense of smell more complete. Different scent molecules degrade at different rates, and our scent receptors pick up on them accordingly. Some smells are easier to detect and process in a fast-moving airstream like the decongested nostril, while others are better detected in the slower airstream of the congested nostril. Nasal cycling also seems to keep the nose maintained for its function as an air filter and humidifier. The alternating congestion gives the mucous and cilia (the tiny hairs up in your nose) in each nostril a well-deserved break from the onslaught of air and prevents the insides of your nostrils from drying out, cracking and bleeding.

Another snot mystery: Why does my nose run when I cry?

When you cry, most of your tears spill over your lower eyelid and run down your face. Some of them, though, don’t quite make it over the hill and instead go back down into the tear ducts and into the nasal cavity, which is connected to the ducts. If you’re really bawling, you’ll have quite a few tears running down into the nose, and their salinity also helps loosen up mucous and get it flowing, giving you a runny nose.

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History
The Queen of Code: Remembering Grace Hopper
By Lynn Gilbert, CC BY-SA 4.0, Wikimedia Commons

Grace Hopper was a computing pioneer. She coined the term "computer bug" after finding a moth stuck inside Harvard's Mark II computer in 1947 (which in turn led to the term "debug," meaning solving problems in computer code). She did the foundational work that led to the COBOL programming language, used in mission-critical computing systems for decades (including today). She worked in World War II using very early computers to help end the war. When she retired from the U.S. Navy at age 79, she was the oldest active-duty commissioned officer in the service. Hopper, who was born on this day in 1906, is a hero of computing and a brilliant role model, but not many people know her story.

In this short documentary from FiveThirtyEight, directed by Gillian Jacobs, we learned about Grace Hopper from several biographers, archival photographs, and footage of her speaking in her later years. If you've never heard of Grace Hopper, or you're even vaguely interested in the history of computing or women in computing, this is a must-watch:

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science
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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