Saturn has more than 60 moons, but a handful do more than spangle the planet’s sky. Snuggled close to Saturn, these innermost moons are small — Epimetheus, one of the largest, stretches just 72 miles across. Yet these shepherd moons — orbiting at the edges of some of the main rings or within the gaps — wield enough gravity to herd icy ring particles into place. Some, like Atlas, tend the bangles by pruning and neatening their edges. Pan and Daphnis mow lanes between the rings. “These moons kind of sweep out cavities within the rings,” said Bonnie Buratti of NASA’s Jet Propulsion Laboratory, who described the mini-moons in a study published in Science. But the rings sculpt the moons, too, coating them with colorful mounds of ice and crafting some unusual shapes.

Here’s how mosquitoes are sniffing you out

It’s actually difficult to attract mosquitoes. Every time a mosquito sneaks up to an animal thousands of times its size to feed, it is trying something dangerous, said Matthew DeGennaro, a mosquito geneticist. The right cues — a whiff of exhaled carbon dioxide, a bit of body odor, other mysterious elements of animal smell — have to be there, or mosquitoes won’t take the risk. But how they do they pick up these cues? In a paper in Current Biology, DeGennaro and colleagues report that they have unraveled part of the mystery: They’ve identified a receptor in mosquito antennae that allows them to detect lactic acid in human sweat. The knowledge could lead to better repellents and traps, DeGennaro said.

Sun bears are solitary, but still communicate

The sun bears were making faces at each other. And that was a surprise. Scientists have been studying the facial expressions of primates for years. They have evolved in complex societies and thus need to be able to convey their joy, anger and other emotions. But sun bears are mostly solitary. In a study in Scientific Reports, researchers led by primatologist Marina Davila-Ross say sun bears do use facial expressions to communicate, suggesting that social creatures do not have a monopoly on expressing themselves this way. The researchers found that very often when one bear made an expression, the other would make it a second later — and so precisely that the scientists believe they were mimicking each other.

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