10 Facts About the Dwarf Planet Makemake

Within the Kuiper Belt—that ring of ices and volatile material beyond the orbit of Neptune—are all but one of the known dwarf planets in the solar system. Pluto is the largest of that class of planet, with Eris a close second. Next on that list is the plucky Makemake, a relatively reflective, distant, and dynamic world. From a distance of 4.26 billion miles, much about Makemake remains a mystery, though scientists are chipping away at the unknowns. Here are a few things they know—but you might not—about Makemake.


Makemake's orbit is a half-billion miles farther from the Sun than Pluto's. One day on the distant dwarf lasts nearly as long as ours does—22.5 hours—but the small world is in no rush to circle our star: One Makemakean year is 305 Earth years long. With a diameter of about 880 miles, the dwarf planet is about two-thirds the size of Pluto—and about three times the size of the 277-mile-long Grand Canyon—making it the 25th largest object in the solar system. That might not seem very impressive until you consider that there are hundreds of thousands of objects orbiting the Sun.


Despite being smaller than Pluto, Makemake is the second brightest object in the Kuiper Belt. Its reflective surface is a result of an abundance of methane and ethane ice present there; half-inch pellets of frozen methane may riddle its frigid surface. It's likely a reddish-brown hue, though its distance makes it hard to tell for sure.


Mike Brown of Caltech discovered Makemake a few days after Easter in 2005. (Brown also discovered the dwarf planets Eris and Haumea.) Before it received its formal name, Brown's team called it "Easterbunny." To other astronomers, its provisional name was "2005 FY9."


In 2008, Easterbunny/2005 FY9 was designated a dwarf planet by the International Astronomical Union (IAU). When deciding what name to submit to the IAU, the proximal holiday led Brown to its namesake island (itself first visited by a European around Easter 1722), which led Brown to its people and their religious heritage. Makemake is the creator god of the Rapa Nui people of Easter Island.


The discovery of Makemake and, just a few months before, Eris—which is larger than Pluto—forced astronomers to reconsider what, exactly, makes a planet a planet. A planet has to orbit the Sun, have enough mass that its gravity forces it into a round shape, and clear its immediate space neighborhood of other objects. Eris, Makemake, Pluto, and Haumea fail to meet all three criteria in one way or another. (Pluto's downfall: It doesn't clear its neighborhood.) After fierce debate among astronomers around the world, the IAU created the new category of "dwarf planet" for these objects—including Pluto. (Thanks, Makemake.)


Makemake is no mere round rock in space. In many ways, it's a sibling of Pluto. Its surface, for example, is dominated by methane, a hyper-volatile compound that is also found on Pluto's surface. ("Volatile" means it reacts to changes in temperature.) "The processes on Pluto are driven by the movement of volatiles around the surface as temperatures change," says Alex Parker, a senior research scientist at the Southwest Research Institute in Boulder, Colorado. "If a world has a volatile-dominated surface—like Makemake does—it probably has dynamic processes on it similar to Pluto."


family of planets

In the illustration above, Makemake has no moon. That's because it was only discovered in 2016 by Parker [PDF], who spotted it in data collected by the Hubble Space Telescope. "It was actually a very obvious satellite," he tells Mental Floss. "I didn't have to do too much digging into the data to get it to pop out; it just sort of stood out clear as day."

He continues: "As soon as I found it, I was also crestfallen, because I was sure other people who had done the preliminary analysis of the data would have almost certainly seen it—and that I would have been late to the party. My first question to the principal investigator of the program was, 'Hey, have you seen the moon in the Makemake data?' And I was sure the answer was going to be, 'Yes.' But it was, 'There's a moon in the Makemake data?' It was super exciting realizing that thing I was sure other people had spotted hadn't been and that I was the first to see it."

The moon's current official designation is S/2015 (136472), and it's nicknamed MK 2. More than 1300 times fainter than Makemake, it's estimated to be a mere 100 miles wide.


Makemake's moon is more than a celestial feature; it's a tool for scientists. As the 105-mile-wide object (nearly twice as long as the Panama Canal) and its planet pass in front of one another, astronomers can use the changes in brightness to map the Makemakean surface. "Just like we had preliminary maps of Pluto before we got there, we can actually use the moon as it passes in front of Makemake as a tool to map it," says Parker.

Specifically, as one object crosses the other, parts of the obscured object can be isolated. Astronomers can then derive the brightness of just the isolated part of the body (rather the whole body at once). Darker areas and lighter areas can then be mapped to the object, and models can help determine whether scientists are seeing terrain features, for example. They're not going to be naming mountains with this technique, but they can find interesting areas worth further study and modeling.

"There are many ways you can think of Makemake as a sort of Pluto prior to the New Horizons exploration. We are just starting to get glimpses of what it looks like," Parker says. "It could be this dynamic and active world, and I think that's exciting."


Scientists aren't sure how Makemake's day-night cycle influences its landforms and surface processes (which include things like geology or interactions between the atmosphere—if it has one—and the surface). The history and origin of its moon are also unknown, and raise other interesting questions for scientists. Theorists who work on planetary formation, and astronomers who study the motions of celestial objects, are revising their models to account for why moons are a defining feature for dwarf planets—including the weird ones—when half of the terrestrial planets in the solar system (Mercury and Venus) lack moons.

"Why are moons so ubiquitous among dwarf planets in the Kuiper Belt? At this point, every one of the largest objects in the Kuiper Belt [except one] has at least one moon," Parker says. "Some have two. Some have five. And so if you come up with a process for growing these planets [like accretion] ... one of the end states of that process needs to be that they all end up with at least one moon."


No missions have yet been launched to Makemake, though the New Horizons spacecraft, having completed its reconnaissance of Pluto, has plunged deeper into the Kuiper Belt to study at least one other object there. Back on Earth, planetary scientists are considering frameworks for future Kuiper Belt missions. The development of new propulsion technologies by engineers will enable more science in single expeditions. In the longer term, orbiter missions will return to visited bodies and study them in finer detail. "Given how much variety there is in the Kuiper Belt," Parker says, "it's going to be a pretty exciting time as we shed light on these worlds."

science fiction
Why So Many Aliens in Pop Culture Look Familiar

Aliens have been depicted countless times in cinema, from Georges Méliès's A Trip to the Moon (1902) to James Cameron's Avatar (2009). But despite the advancements in special-effects technology over the past century, most aliens we see on screen still share a lot of similarities—mainly, they look, move, and interact with the world like humans do. Vox explains how the classic alien look came to be in their new video below.

When you picture an alien, you may imagine a being with reptilian skin or big, black eyes, but the basic components of a human body—two arms, two legs, and a head with a face—are likely all there. In reality, finding an intelligent creature that evolved all those same features on a planet millions of light-years away would be an extraordinary coincidence. If alien life does exist, it may not look like anything we've ever seen on Earth.

But when it comes to science fiction, accuracy isn't always the goal. Creating an alien character humans can relate to may take priority. Or, the alien's design may need to work as a suit that can be worn by human performers. The result is a version of extraterrestrial life that looks alien— but not too alien—to movie audiences.

So if aliens probably won't have four limbs, two eyes, and a mouth, what would they look like if we ever met them person? These experts have some theories.

[h/t Vox]

A Year in Space Changed How Astronaut Scott Kelly's Genes Behaved

After spending 342 consecutive days onboard the International Space Station from 2015 to 2016, astronaut Scott Kelly now holds the record for longest single space mission by an American. But his "One-Year" study with NASA was about more than breaking records: Its purpose was to show how prolonged time in orbit would effect Kelly's genetic makeup compared to that of his identical twin brother on Earth. Now, following recent evaluations of the two men, it appears that Scott Kelly's gene expression was significantly altered by his time in space, reports.

NASA announced the most recent findings from its Twins Study ahead of a more comprehensive paper combining the work of multiple teams of researchers that is slated for later in 2018. Like his brother Scott, Mark is also an astronaut, making the pair the only twin astronauts in history. So when NASA was looking for a way to study the long-term effects of space life, the siblings were a perfect fit.

As Scott was sending tweets and blowing bubbles on the ISS, Mark stayed on Earth to serve as the control. Biological samples taken from both subjects before, during, and after the space flight showed some dramatic differences. According to an investigation conducted by Susan Bailey of Colorado State University, Scott's telomeres, the protective "cap" at the ends of chromosomes that shorten as we age, got longer in space. The telomeres began shrinking back to preflight levels, however, a few days after Scott's return to Earth. Scott was subjected to regular exercise and a restricted diet aboard the ISS, so the new lifestyle may explain the sudden telomere boost.

Other genetic differences stuck around even months after landing. "Although 93 percent of genes' expression returned to normal post-flight, a subset of several hundred 'space genes' were still disrupted after return to Earth," acccording to a NASA press release. About 7 percent of Scott's genes may show longer-term changes, included the genes associated with DNA repair, immune health, bone formation, hypoxia (an oxygen deficiency in the tissues) and hypercapnia (excessive carbon dioxide in the bloodstream).

A long list of factors, like radiation, caloric restriction, and zero gravity, may have contributed to the results. NASA plans to use these findings to develop countermeasures against these effects, which will be essential if the agency plans to send humans to Mars, a journey that could take three times as long as Scott Kelly's ISS mission.


Editor's note: We updated the headline and one line of this story to more accurately reflect the research findings. We apologize for the error. 


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