Rational numbers are impossible!

Brilliant, high-speed math vlogger Vi Hart has revisited the topic of the sizes of infinities.

Read the rest

NASA has a plan to just tow an asteroid around space like it's an old car

The crazy part about NASA's Asteroid Initiative isn't so much the part where we land human beings on an asteroid. That's cool and all, sure. But the bit that precedes it is actually a little bit more mindblowing. To make that landing work, we'll first have to send out robotic spacecraft to essentially capture an asteroid and tow it into a stable orbit around the Moon. Yeah. Seriously. Welcome to living in the future, dudes.

NASA had Apollo-era plans to send humans to Mars and Venus

In an alternate universe — one where Americans had a LOT more enthusiasm for spending money on massive space projects than we've ever actually demonstrated — the 1970s and 1980s might have been the era of manned missions to Mars and Venus. Amy Shira Teitel writes about how this could have been possible, using only the now-antiquated technology that got us to the Moon and back.

See your own brain waves in this trippy optical illusion

If you look at this wheel out of your peripheral vision, you should see it flicker or strobe a bit. (To me, it almost looks like a fast pulsating motion, coming from the center of the wheel.) And that's neat. Optical illusions are usually pretty neat.

But, as the blogger Neuroskeptic writes, there's some reason to think that what you're seeing might be something even more awesome than just your brain being misled. A study published this month in The Journal of Neuroscience suggests that the flickering is actually a visual representation of the rhythmic alpha waves that are constantly pulsating through your brain.

Read the rest

Why is the sky dark at night?

So, the sky looks blue because of the particular gases in our atmosphere reflect and scatter the blue wavelengths of light from the Sun. Fair enough. But that leads directly to a second question that, I'm ashamed to say, I never really thought to ask — why doesn't the light from all the stars in the Universe reflect and scatter off our atmosphere, producing a blue sky, all the time?

This Minute Physics video provides a great explanation, which is grounded in both the timey-wimeyness of astrophysics and the limitations of our own human biology.

Via BrainPickings

The weird, black, spidery things of Mars

See those weird, black, spidery things dotting the dunes in this colorized photo taken by the Mars Reconnaissance Orbiter in 2010? Yeah. Nobody knows what the hell those things are.

What we do know about them just underlines how incredibly unfamiliar Mars really is to us. First spotted by humans in 1998, these splotches pop up every Martian spring, and disappear in winter. Usually, they appear in the same places as the previous year, and they tend to congregate on the sunny sides of sand dunes — all but shunning flat ground. There's nothing on Earth that looks like this that we can compare them to. It's a for real-real mystery, writes Robert Krulwich at NPR. But there are theories:

Scientists from the U.S. Geological Survey, from Hungary, from the European Space Agency have all proposed explanations; the leading one is so weird, it's transformed my idea of what it's like to be on Mars. For 20 years, I've thought the planet to be magnificently desolate, a dead zone, painted rouge. But imagine this: Every spring, the sun beats down on a southern region of Mars, morning light melts the surface, warms up the ground below, and a thin, underground layer of frozen CO2 turns suddenly into a roaring gas, expands, and carrying rock and ice, rushes up through breaks in the rock, exploding into the Martian air. Geysers shoot up in odd places. It feels random, like being surprise attacked by an monstrous, underground fountain.

"If you were there," says Phil Christensen of Arizona State University, "you'd be standing on a slab of carbon dioxide ice. All around you, roaring jets of carbon dioxide gas are throwing sand and dust a couple hundred feet into the air." The ground below would be rumbling. You'd feel it in your spaceboots.

Read the rest of Robert Krulwich's post — and check out some spectacular photos of the things — at NPR

This is real life. Not Tron.

This amazing photo was taken by astronaut Don Pettit on board the International Space Stations—of which you can see a chunk at the top of the frame. It's part of a whole series of absolutely stunning photos that you need to go check out as soon as you have a free 20 minutes to spend staring at your monitor and going, "Woah," to yourself over and over.

Here's what Pettit had to say about the process.

“My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, the ‘stack’ them using imaging software, thus producing the longer exposure.”

Via Smithsonian, which is where you can find the rest of Don Pettit's photos.

The secret lives of citrus fruit

Okay, I had no idea that lemons and grapefruit are actually hybrid mixes of other fruits. How did I get to age 31 and miss this? Better yet, both citruses were born accidentally, of illicit love affairs not arranged by human hands. Lemons are the love child of citron and orange. Grapefruit the natural daughter of Asian pomelo and Barbados sweet orange. (Via David Despain)

It is fun to live in the future

So, somebody has invented a tactile touch screen interface where buttons rise out of the flat surface like the Lady of the Lake, and disappear again when you're done with them. I'm not sure whether it's reasonable for my mind to be as blown as it is by this. Coming to products near you sometime next year, supposedly. (Via Laura Kling)

An LCD pixel and a grain of sand are roughly the same size

Cary Huang's amazing Scale of the Universe animation has been updated—now with a better format, extra background information about the objects whose sizes are being compared, and more opportunities to blow your mind. "Holy sh$#! The Grand Canyon is bigger than Rhode Island?"

A view inside a nuclear reactor

This is not a metaphorical view inside a nuclear reactor. This is for real-real.

This month, the good folks at TEPCO sent a remote-controlled endoscope and thermometer into the containment vessel of Fukishima's crippled reactor #2, hoping to learn something about the level of cooling water, the state of the fuel rods, and the temperature in the reactor. The view is obscured by steam, the effects of radiation, and (are you sitting down) actual goddam gamma rays just whizzing by. According to the PBS Frontline blog, those are the little streaks and flashes that you see in this video.

The probe revealed corroded piping and dripping humidity, but did not reveal the water’s surface level, which TEPCO had expected to be as high as four meters. The containment vessel was flooded with seawater during the reactor meltdown when other attempts to cool it failed. Current water levels inside the reactor remain unknown.

The probe’s thermometer function proved more revealing; it recorded the interior temperature at 44.7 degrees centigrade (112 degrees Farenheit), demonstrating that the unit’s own thermometer, thought to be off by as many as 20 degrees, is still functioning accurately.

Video Link

Killer whale kills great white shark

Demitri Martin has observed that whale watching is often indistinguishable from watching people be disappointed. But not all the time. National Geographic has a short video about a 1997 whale watching excursion when the people got to watch a killer whale take down a great white shark. (Feel free to make heavy metal devil hands at your computer screen at any time while watching this video.)

The really cool thing? To pull off this kill, the whale had to learn a trick about shark anatomy and behavior. Treehugger's Jaymi Heimbuch explains:

According to National Geographic, "To prey upon the shark, the Orca has learned how to immobilize it by turning it on its back -- a state called 'tonic immobility.'" Sharks freeze when rolled onto their backs. And that's exactly the strategy the whale in this film seems to have taken, keeping the shark immobile until it suffocates, then and feeding on it.

If that's not worth a little air guitar in that whale's honor, I don't know what is.

Video Link

Inside a fossilized cell

Here's something that's just a little mind-blowing: Synchotron tomography, a type of medical imaging related to CT scanning, allows scientists to look inside the cells of fossils. Check out this post on Lawn Chair Anthropology about a recently published paper that used synchotron tomography to study clumps of fossilized cells and rule them out as being one of earliest ancestors.

Next up: The search for alien light pollution

Today's best telescopes could see the amount of light produced by Tokyo from as far away as the Kuiper Belt. Future telescopes may be able to hunt for alien civilizations by looking for artificial lighting. (Via Gary King)