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See What It Looks Like to Land on Saturn's Largest Moon, Titan

In 2005, the European Space Agency's Huygens probe—which had been sent into space with its mothership, NASA’s Cassini spacecraft, to learn more about Saturn and its moons—became the first spacecraft to land on an object in the outer solar system. That object was Titan, a hazy, planet-like moon of Saturn. Now, 12 years after the historic voyage, Mashable reports that NASA has released a video of Huygens's descent.

Huygens took samples of Titan’s atmosphere and captured hundreds of photos of the moon. These images revealed a new, alien world with rugged mountains, dramatic gorges, and dark drainage channels that were suggestive of liquid methane rivers.

“The Huygens images were everything our images from orbit were not,” planetary scientist Carolyn Porco, who worked as the Cassini imaging team lead at the Space Science Institute in Boulder, Colorado, said in a NASA press release. “Instead of hazy, sinuous features that we could only guess were streams and drainage channels, here was incontrovertible evidence that at some point in Titan's history—perhaps even now—there were flowing liquid hydrocarbons on the surface. Huygens's images became a Rosetta Stone for helping us interpret our subsequent findings on Titan."

The Huygens probe only transmitted data during its descent; after it landed on Titan, it went silent. The Cassini spacecraft has continued to explore Titan from above, capturing images of sand dunes and lakes of liquid methane and ethane. Cassini is currently in its final year of exploration; its mission is slated to end in September 2017.

In the video below, you can relive the Huygens probe's historic descent, from atmospheric entry to touchdown.

[h/t Mashable]

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There May Be an Ancient Reason Why Your Dog Eats Poop
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Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]

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The Prehistoric Bacteria That Helped Create Our Cells Billions of Years Ago
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We owe the existence of our cells—the very building blocks of life—to a chance relationship between bacteria that occurred more than 2 billion years ago. Flash back to Bio 101, and you might remember that humans, plants, and animals have complex eukaryotic cells, with nucleus-bound DNA, instead of single-celled prokaryotic cells. These contain specialized organelles such as the mitochondria—the cell’s powerhouse—and the chloroplast, which converts sunlight into sugar in plants.

Mitochondria and chloroplasts both look and behave a lot like bacteria, and they also share similar genes. This isn’t a coincidence: Scientists believe these specialized cell subunits are descendants of free-living prehistoric bacteria that somehow merged together to form one. Over time, they became part of our basic biological units—and you can learn how by watching PBS Eons’s latest video below.

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