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.

This 'Time-Traveling Illusion' Is Designed to Trick Your Brain

A team of researchers from the California Institute of Technology (Caltech) have designed an illusion that might trick your brain into seeing things that aren’t there, the New Atlas reports.

Dubbed the Illusory Rabbit, it provides instructions that are simple enough to follow. Start playing the YouTube video below and look at the cross in the middle of the screen while also watching for flashes that appear at the bottom of the screen. Most importantly, you’ll want to add up the number of flashes you see throughout the video. (And make sure your volume is up.)

We don’t want to spoil the fun, so before we explain the science of how it works, check out the video and try it for yourself.

Did you see three flashes paired with three beeps? You’re not alone. This is due to a phenomenon called postdiction, which is a little like the opposite of prediction. According to a paper outlining these findings in the journal PLOS ONE, postdiction occurs when the brain processes information retroactively [PDF]. This occurs in such a way that our perception of earlier events is altered by stimuli that come later. In this case, you might think you missed the flash paired with the second of the three beeps, so your mind goes back and tries to make sense of the missing information. That's why you may see an “illusory flash” in the middle of the screen, sandwiched between the two real flashes.

For this reason, the researchers call the mind trick a “time-traveling illusion across multiple senses” (in this case, vision and hearing). It’s successful because the beeps and flashes occur so rapidly—in less than one-fifth of a second. The senses essentially get confused, and the brain tries to fill in the gaps retroactively.

"Illusions are a really interesting window into the brain," the paper’s first author, Noelle Stiles, said in a statement. "By investigating illusions, we can study the brain's decision-making process.” Researchers wanted to find out how the brain “determines reality” when a couple of your senses (in this case, sight and hearing) are bombarded with noisy and conflicting information. When the brain isn’t sure of what’s going on, it essentially makes up information.

“The brain uses assumptions about the environment to solve this problem,” Stiles said. “When these assumptions happen to be wrong, illusions can occur as the brain tries to make the best sense of a confusing situation. We can use these illusions to unveil the underlying inferences that the brain makes."

[h/t New Atlas]

How Did 6 Feet Become the Standard Grave Depth?

iStock
iStock

It all started with the plague: The origins of “six feet under” come from a 1665 outbreak in England. As the disease swept the country, the mayor of London literally laid down the law about how to deal with the bodies to avoid further infections. Among his specifications—made in “Orders Conceived and Published by the Lord Mayor and Aldermen of the City of London, Concerning the Infection of the Plague”—was that “all the graves shall be at least six feet deep.”

The law eventually fell out of favor both in England and its colonies. Modern American burial laws vary from state to state, though many states simply require a minimum of 18 inches of soil on top of the casket or burial vault (or two feet of soil if the body is not enclosed in anything). Given an 18-inch dirt buffer and the height of the average casket (which appears to be approximately 30 inches), a grave as shallow as four feet would be fine.

A typical modern burial involves a body pumped full of chemical preservatives sealed inside a sturdy metal casket, which is itself sealed inside a steel or cement burial vault. It’s less of a hospitable environment for microbes than the grave used to be. For untypical burials, though—where the body isn’t embalmed, a vault isn’t used, or the casket is wood instead of metal or is foregone entirely—even these less strict burial standards provide a measure of safety and comfort. Without any protection, and subjected to a few years of soil erosion, the bones of the dearly departed could inconveniently and unexpectedly surface or get too close to the living, scaring people and acting as disease vectors. The minimum depth helps keep the dead down where they belong.

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

This article originally appeared in 2012.

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