Ice in the Air Makes Earth Sparkle From Space

NASA
NASA

A satellite orbiting Earth has captured images of our planet seemingly studded with flecks of gold glitter—the result, scientists say, of sunlight reflecting off ice particles in our atmosphere. They published their findings in the journal Geophysical Research Letters.

Alexander Marshak helps direct the Deep Space Climate Observatory (DSCOVR), a joint venture between NASA and NOAA. Tucked aboard that observatory is an instrument called EPIC, or the Earth Polychromatic Imaging Camera. As DSCOVR passes between Earth and the Sun, EPIC takes photo after photo, like a proud parent on prom night.

And just like an eager teen dressed for the dance, our planet is apparently just decked out in sparkles.

Astronomers have known about the little gold flashes of light for decades; legendary cosmos-gazer Carl Sagan even described them in a journal article three years before his death. In reviewing images from the Galileo telescope, Sagan and his colleagues developed a reasonable theory: The flashes were the ordinary reflections of sunlight bouncing off flat stretches of the ocean. After all, they said, there were no flashes over land.

But there were. Marshak and his colleagues first noticed a few tiny glints over landmasses in EPIC’s images. Then they went back to Galileo’s snapshots and found even more.


An image from the EPIC instrument aboard DSCOVR, taken on Dec. 3, 2015, shows a glint over central South America (circled in red).
NASA/NOAA/U.S. Air Force.

“When I first saw [a small flash] I thought maybe there was some water there,” Marshak said in a statement, “or a lake the sun reflects off of. But the glint is pretty big, so it wasn’t that.”

The flashes are also too big, and too significantly positioned relative to the Sun, to be the result of electric storms. “Lightning doesn’t care about the sun and EPIC’s location,” Marshak said, and “The source of the flashes is definitely not on the ground.”

That leaves only our atmosphere, which is sprinkled with a layer of fine ice particles. When the ice particles are floating horizontally and the Sun hits them just right, those particles coruscate better than a tiara under a disco ball.

And while Earth will always be the prom queen of our hearts, Marshak says we may not be the only bedazzled planet out there; in the future, researchers may be able to use these flashes to study exoplanets.

Lítla Dímun: The Smallest of the Faroe Islands Has Its Very Own Cloud

While some islands are known for their unusual geography or unique history, Lítla Dímun is notable for its weather. The island, which is the smallest of Denmark's Faroe Islands chain, is often capped by a lens-shaped cloud, making it resemble a scene from a fairytale.

According to Mental Floss's own Kerry Wolfe writing for Atlas Obscura, the cloud floating above Lítla Dímun is a lenticular cloud. This type of cloud forms when moist air flows over a protruding geological feature, like a mountain top. When the wind moving up the landmass hits the air current directly above it, a sort of wave is created on the downwind side of the mountain. The moist air falling down this wave evaporates and then condenses into a large, flying-saucer-shaped cloud atop the mountain peak as a result.

Another factor that makes Lítla Dímun distinct is that it's the only one of the 18 main Faroe Islands without human inhabitants. Visitors to the mystical location will instead find a thriving population of sheep. Originally, Lítla Dímun was home to a group of feral sheep likely dating back to the Neolithic era. But they were hunted to extinction in the 19th century. Domesticated sheep were introduced there around the same time, and today, farmers visit the island once a year to round up their flocks.

One of the few signs of human life are the ropes farmers use to scale the cliff faces bordering the island. Even if you have rock-climbing skills, Lítla Dímun may be dangerous to visit. A boat ride to the rocky shore is only possible when the surrounding sea is calm.

[h/t Atlas Obscura]

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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