7 Surprising Facts About Pluto


Pluto, the ninth planet of the classical solar system was, until 2015, largely a mystery—a few pixels 3.6 billion miles from the Sun. When NASA's New Horizons spacecraft arrived at the diminutive object in the far-off Kuiper Belt, planetary scientists discovered a geologist's Disneyland—a mind-blowing world of steep mountains, smooth young surfaces, ice dunes, and a stunning blue atmosphere. To learn more, Mental Floss spoke to Kirby Runyon, a planetary geomorphologist at the Johns Hopkins University Applied Physics Laboratory and a scientist on the NASA New Horizons geology team. Here is what you need to know about Pluto, the small world with the biggest heart in the solar system.


At 1473 miles in diameter—about half the width of the United States—Pluto is the smallest of the nine classical planets and the largest discovered "trans-Neptunian object" (i.e., an object beyond the planet Neptune). As could be expected, it is cold on Pluto's surface: around -375°F. Its gravity is about 1/15 that of Earth. It has five moons: Charon, Nix, Hydra, Kerberos, and Styx. Charon is the largest of the moons by far, with a diameter about half that of Pluto. It takes about 248 Earth years for Pluto to circle the Sun, and during that time, its highly elliptical orbit takes it as far as 49 astronomical units from our star, and as close as 30.


Pluto the planet was discovered on February 18, 1930 by astronomer Clyde Tombaugh at the Lowell Observatory in Flagstaff, Arizona. It was named later that year by Venetia Burney, an 11-year-old girl in England. She first learned of the new, nameless planet from her grandfather, who mentioned it while reading the newspaper. Burney was interested in Greek and Roman mythology at the time, and she immediately suggested Pluto.

Her grandfather was impressed, and mentioned it in a note to a friend of his, who taught astronomy at Oxford. The astronomy professor passed word to Lowell Observatory, and the astronomers there took an immediate liking to it. It helped that the first two letters of Pluto are the initials of the observatory's (then dead) founder, Percival Lowell. Note that Burney did not get the name from the Disney dog. Just the opposite: The dog, which premiered the same year as Pluto was discovered, was likely named by Walt to ride the planet's publicity wave. Scientists and cartoonists alike have yet to explain how the then-unseen planet and dog ended up being more or less the same color.


Space elevators are a science fiction staple, and advances in carbon nanotubes have made their prospects, if not likely, then certainly possible. The idea is to bring a large object such as an asteroid into a geostationary orbit at Earth's equator, and essentially connect that object and the Earth with a cable or structure. You could then lift things into orbit without the need for rockets. According to Runyon, the unique orbital characteristics of Pluto and Charon create interesting opportunities for the very, very distant future of engineering.

The two worlds are tidally locked. Charon's orbit is precisely the same duration as Pluto's rotation, meaning that if you stood on Pluto's surface, the moon would hover over the same spot, never rising or setting. "Because they are binary, tidally locked, literally orbiting each other in a perfect circle, you could build a space elevator that goes from one planet to the other, from Pluto to Charon," Runyon tells Mental Floss. "And it would touch the ground in both places, physically linking them. And you could literally climb a ladder from one to the other."


In 2015, the New Horizons spacecraft arrived at the Pluto system and turned a few pixels into a real world. The famous first image released by NASA is not a straight-on shot from Pluto's side, with the top being the North Pole and bottom being the south. It is in reality a view from Pluto's higher latitudes, looking down. (The heart, in other words, is quite higher up on the planet than the picture suggests.) Because New Horizons was a flyby craft and not an orbiter, planetary scientists don't know what 40 percent of the planet looks like.


The traditional classroom solar system model of a light bulb as the Sun and planets on wires extending from it represents a nice flat orbital plane known as the ecliptic, and for most of the solar system, that's pretty close to the truth. But not for Pluto, which has a 17-degree inclination relative to the ecliptic. Moreover, like Uranus, its rotation is tipped on its side, and it rotates backward (east to west). No one knows why, according to Runyon. "It's probably the result of an ancient impact," he says. "One not strong enough to disrupt planet but enough to tip on its side. This might have been the Charon-forming impact, which would be similar to how our moon is formed."


Astronomers have long known that Pluto has an atmosphere. During stellar occultations (that is, when it moves in front of stars), astronomers can see the star dim, and then completely go out, and then reappear dimly, and then return to its full brightness. That dimming is caused by the planet's atmosphere. Astronomers are furthermore able to track its density over time. Because Pluto is so far from the Sun, the ice on its surface sublimates: It goes from a solid directly to a gas without first becoming a liquid. When Pluto reached perihelion (as close to the Sun as its gets in an orbit) in 1989, the expectation was that the atmosphere would begin to collapse entirely: that it would freeze out, basically, and fall to the surface.

"A good comparison is when it snows on Earth," says Runyon. "Snow is basically the water vapor in the atmosphere freezing out and falling to the surface, leaving Earth's atmospheric density slightly lower than it would be otherwise." In Pluto's case, the thought was that the complete atmosphere would freeze out and fall onto the planet's surface.

It didn't happen. "Pluto's atmosphere is denser than we thought it would be," Runyon explains. "Even now as it's moving farther from the Sun, its atmosphere is puffier than ever." One model says that while the atmosphere does thin as ices fall to the surface, it never completely freezes and falls.


Scientists on the New Horizons team didn't expect to see Pluto's atmosphere during the flyby. "When we spun New Horizons around after closest approach and looked back at Pluto—being basically backlit from the Sun—we could see the atmosphere," he says. "We knew we'd be able to detect it, but to see it, and to see that the sunrise and sunset on Pluto is this ethereal electric blue—nobody anticipated that." Runyon says that the New Horizons found discrete atmospheric layers that could be traced for hundreds of miles. "Pluto has what's called a stably stratified atmosphere. The coldest layer is on the bottom and it gets warmer as you go up," he says.

"In science, you test hypotheses, but before you can even do that you need to figure out what's there in the first place. To me, that's the most exciting part of science. The most exciting part of space exploration is to see something for the first time, and that's what New Horizons was. And to turn around and look back at the Sun and see a beautiful atmosphere with the gorgeous layers through it is just astonishing," he says. 

What Happens to Your Body If You Die in Space?


The coming decades should bring about a number of developments when it comes to blasting people into orbit and beyond. Private space travel continues to progress, with Elon Musk and Richard Branson championing civilian exploration. Professional astronauts continue to dock at the International Space Station (ISS) for scientific research. By the 2040s, human colonists could be making the grueling journey to Mars.

With increased opportunities comes the increased potential for misadventure. Though only 18 people have died since the emergence of intragalactic travel in the 20th century, taking more frequent risks may mean that coroners will have to list "space" as the site of death in the future. But since it's rare to find a working astronaut in compromised health or of an advanced age, how will most potential casualties in space meet their maker?

Popular Science posed this question to Chris Hadfield, the former commander of the ISS. According to Hadfield, spacewalks—a slight misnomer for the gravity-free floating that astronauts engage in outside of spacecraft—might be one potential danger. Tiny meteorites could slice through their protective suits, which provide oxygen and shelter from extreme temperatures. Within 10 seconds, water in their skin and blood would vaporize and their body would fill with air: Dissolved nitrogen near the skin would form bubbles, blowing them up like a dollar-store balloon to twice their normal size. Within 15 seconds, they would lose consciousness. Within 30 seconds, their lungs would collapse and they'd be paralyzed. The good news? Death by asphyxiation or decompression would happen before their body freezes, since heat leaves the body slowly in a vacuum.

This morbid scene would then have to be dealt with by the accompanying crew. According to Popular Science, NASA has no official policy for handling a corpse, but Hadfield said ISS training does touch on the possibility. As he explained it, astronauts would have to handle the the body as a biohazard and figure out their storage options, since there's really no prepared area for that. To cope with both problems, a commander would likely recommend the body be kept inside a pressurized suit and taken someplace cold—like where garbage is stored to minimize the smell.

If that sounds less than regal, NASA agrees. The company has explored the business of space body disposal before, and one proposition involves freeze-drying the stiff with liquid nitrogen (or simply the cold vacuum of space) so it can be broken up into tiny pieces of frozen tissue, which would occupy only a fraction of the real estate that a full-sized body would.

Why not eject a body, like Captain Kirk and his crew were forced to do with the allegedly dead Spock in 1982's Star Trek II: The Wrath of Khan? Bodies jettisoned into space without a rocket to change their trajectory would likely fall into the wake of the spacecraft. If enough people died on a long trip, it would create a kind of inverted funeral procession.

Even if safely landed on another planet, an astronaut's options don't necessarily improve. On Mars, cremation would likely be necessary to destroy any Earth-borne bacteria that would flourish on a buried body.

Like most everything we take for granted on Earth—eating, moving, and even pooping—it may be a long time before dying in space becomes dignified.

[h/t Popular Science]

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Life on Nearby Exoplanet Barnard's Star B Might Be Possible, According to Astronomers


Despite contradictory statements from UFO eyewitnesses, we have yet to confirm the presence of intelligent life beyond Earth. But astronomers continue to flirt with that hope. The most recent speculation comes from Barnard’s Star, the second-closest star system to Earth, which is circled by a frozen super-Earth dubbed Barnard's Star b. While its surface might be as cold as -274°F, there may just be potential for life.

According to CNET, the chilly Barnard's Star b—located 6 light years away from Earth—could still be hospitable to living organisms. Astrophysicists at Villanova University speculate the planet could have a hot liquid-iron core that produces geothermal energy. That warmth might support primitive life under the icy surface. A similar situation could possibly occur on Jupiter’s moon, Europa, where tidal heating might allow for subsurface oceans containing living things.

Barnard's Star b has a mass just over three times that of Earth. The conclusions about potential life were drawn by Villanova researchers from 15 years of photometry examination of the solar system [PDF].

“The most significant aspect of the discovery of Barnard’s star b is that the two nearest star systems to the Sun are now known to host planets,” Scott Engle, a Villanova astrophysicist, said in a statement. “This supports previous studies based on Kepler Mission data, inferring that planets can be very common throughout the galaxy, even numbering in the tens of billions. Also, Barnard’s Star is about twice as old as the Sun—about 9 billion years old compared to 4.6 billion years for the Sun. The universe has been producing Earth-size planets far longer than we, or even the Sun itself, have existed.”

Scientists hope to learn more about the potential for life on Barnard's Star b as new, more powerful telescopes are put into use. NASA’s delayed James Webb Space Telescope could be one such solution. Its 21-foot mirror—three times the size of the Hubble—is set to open in 2021.

[h/t CNET]