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NOVA  Understand the world around you. Facebook & Twitter: @NOVAPBS

Mother Nature is an unquestionably prolific architect (look no farther than Yosemite National Park, pictured here). But some of her tools are more subtle than others.

According to a new study, some waterfalls might not require an outside force, like tectonic movements or glacial activity, to form. Rather, a number of breathtaking cascades could in fact come into existence through the natural turbulence of a river—a finding that could rework our understanding of Earth’s geologic history.
📷: Sukee Bennett, NOVA
Read more on NOVA (link in bio👆)

Today (and every day) is a great day to eat pie. And if you’re worried about calories or carbohydrates, don’t be. Math says it’s OK to indulge because it’s #PiDay !

π, or pi, is the ratio of a circle’s circumference to its diameter. Pi is numerically represented as 3.14 (or 3/14 for those following the MM/DD format) and is an irrational number, meaning its exact value is impossible to figure out. Computer scientists, however, have been able to calculate billions of digits of pi. But because there is no recognizable pattern in pi’s digits, we could continue calculating the next digit (and the next, and the next) for millennia—and still not get to a final digit.

Pi’s ubiquity goes beyond math. The number also shows up in the natural world. Look no farther than the disk of the moon, the pupil of an eye, the spiral of the DNA helix, or the concentric rings that travel outward from stones skipped on a pond. And perhaps, pi may also be in that bite of 🥧 you take today. — @scicomm_ana, NOVA digital associate producer
📷: flikr / koka_sexton

Throw on a pair of 3D glasses and take a look at this most recent photo of Ultima Thule. It might pop in three-dimensional splendor!
NASA’s New Horizons mission team released this new image, which is a compilation based on photographs the New Horizons spacecraft snapped during its closest approach to the Kuiper Belt object, officially known as 2014 MU69, over the weekend.
"These views provide a clearer picture of Ultima Thule's overall shape," New Horizons principal investigator Alan Stern, a planetary scientist at the Southwest Research Institute in Colorado, said in a statement.
📷: @nasa / Johns Hopkins Applied Physics Laboratory

Hyena social climbing, even on a small scale, is a relative rarity. Their hierarchies are remarkably stable—perhaps due in part to the fact that spotted hyenas are intelligent, highly adept puzzle solvers capable of cultivating rich social networks. A single spotted hyena can individually recognize each member of a clan of dozens, and will invest this social savvy in allies and adversaries alike.
But, according to research published today, when a female hyena wants to ascend the social ranks and become the alpha of her group, it pays to have good friends.
Read more on NOVA (link in bio👆)

Eight years ago, researchers began an emergency excavation in Peru after receiving some alarming news: Two children had come home after a day of play carrying what looked like human bones.
Sure enough, within hours of breaking ground, the researchers had uncovered the skeletal remains of dozens of bodies dating back some 550 years—evidence of what would become known as one of the largest mass child sacrifices unearthed in history.
Yesterday, the researchers chronicled their years-long excavation in a study published in the journal PLOS ONE. According to the team, around 140 children and 200 young llamas were among those sacrificed around 1450 CE, near the capital of what was then Peru’s Chimú Empire. Though the motivations behind the ritual remain mysterious, it’s possible the massacre occurred in response to a destructive bout of heavy rainfall and coastal flooding.
Read more on NOVA (link in bio👆)
📷: John Verano, Tulane University

A team of researchers is fishing for a new method to treat neurodegenerative disorders. Its tactic? Bait dysfunctional proteins and prevent them from joining together into the kind of toxic globs found in almost every patient with ALS or frontotemporal dementia (FTD).
A protein called TDP-43 is found inside central nervous system cells, drives neurodegeneration when it balls up. While scientists have been studying TDP-43 for more than a decade, exactly why this protein balls up in the first place remained unknown.
Read more on NOVA (link in bio👆)
📷: M. Oktar Guloglu, Wikimedia Commons

NASA’s space explorer Juno arrived to Jupiter in 2016. Since then, it has been hard at work, already performing 18 laps around the gas giant and snapping breathtaking photos of its iconic swirling clouds.
But Juno isn’t the first NASA spacecraft to explore our solar system’s fifth planet. On March 4, 1979—exactly 40 years ago—Voyager 1 took the first photos of Jupiter’s rings, which, being so thin and faint compared to Saturn’s, had been invisible to us on Earth before then.
📷: @nasajpl

Join us in giving polar bears a hearty, warm huzzah in celebration of International Polar Bear Day! These bears are the largest carnivorous mammals living on land—an adult male can weigh as much as 10 adult men. But there's more to them than just their size.
Take their amazing sense of smell, for example. Polar bears can sniff out prey from 16km away. (Now that’s a super-sleuthing snout!)

Happy 100th birthday, @grandcanyonnps!

Our ancient human ancestors once lived only in Africa, in tiny bands of a few thousand hunter-gatherers. Then we moved out of our African cradle, spreading rapidly to every corner of the planet. How did we acquire the skills, technology and talent to thrive in every environment on earth? How did our prehistoric forebears cross the Sahara on foot, survive frigid ice ages, and sail to remote Pacific islands?
Discover these secrets in “Great Human Odyssey,” airing Wednesday, February 27 at 9/8c on @pbs

It’s Friday, so we’re feeling emused.
Happy weekend wishes from the NOVA team!

See these stripes? They’ve plagued evolutionary biologists (albeit, a pretty specific subset of them) for over a century. Several theories regarding their purpose have been batted back and forth, but an evolutionary ecologist involved in a new study is among those who stand staunchly by one in particular: Stripes safeguard against bloodthirsty bugs.
Yesterday, his team published the latest piece in the puzzle, showing that horseflies appear to have trouble touching down on zebra-patterned flanks.
Read more on NOVA (link in bio☝️)

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