10 Facts About the Dwarf Planet Eris

An artist's rendering of the dwarf planet Eris
An artist's rendering of the dwarf planet Eris
ESO/L. Calçada and Nick Risinger (skysurvey.org) // CC BY 4.0

Far beyond the orbit of Pluto exists a celestial body that’s a little smaller, a little colder, and a little denser—the dwarf planet Eris. In Greek mythology, Eris is the goddess of strife, and never was there a more appropriately named body in the solar system. When astronomer Mike Brown of Caltech and his team discovered Eris in 2005, the finding set off a chain reaction that would see the planetary status of Pluto called into question. Here are 10 things you might not know about Eris.

1. An Eridian day is just slightly longer than Earth's.

If you were an astronaut, you wouldn’t find an Eridian day, at 25.9 hours, too disconcerting. This compares favorably with, say, Venus, whose day lasts 5832 hours (admittedly, it's an outlier). An Eridian year is a bit longer than what we're used to, with the dwarf planet completing an orbit of the Sun every 557 Earth years. And that orbit is not along the relatively flat plane with the orbits of most of the other planets of the solar system. Imagine your elementary school solar system model of planets on wires around a light bulb: Instead of a path neatly aligned with the other planets, Eris’s orbit is tilted at a 44 degree angle.

2. Eris was once thought to be bigger than Pluto.

After Eris’s discovery, the best measurements then available placed it as slightly larger than Pluto, with a radius of 722 miles. But after the initial spacecraft reconnaissance of Pluto by New Horizons in 2015, Pluto’s ranking as the ninth-largest planetary object orbiting the Sun was restored; it is now known to have a radius of 736 miles. In comparison, Earth’s Moon has a radius of 1079 miles. Ganymede, Callisto, Io, and Europa (Jupiter’s largest moons), Titan (Saturn’s largest moon), and Triton (Neptune’s largest moon) are also bigger than Pluto. On the other hand, Eris is 34 percent denser than Pluto.

3. Eris is responsible for the big debate over the definition of "planet."

When Brown’s team discovered Eris, it was initially hailed as either the 10th planet of the solar system, or a big problem for scientists who like nicely ordered celestial objects. The discovery of Eris came on the heels of the discoveries of Sedna and Quaoar, both beyond the orbit of Neptune. Astronomers were looking at the possibility of a dozen planets in the solar system or more, because—based on these three—who knew how many Pluto-sized bodies were out there? The International Astronomical Union eventually defined a planet in our solar system as something that has achieved hydrostatic equilibrium (in other words, it's round), orbits the Sun, and has “cleared its neighborhood” (i.e., is gravitationally dominant in its orbit). Yet the debate continues [PDF].

4. It has its own moon.

Eris has a moon called Dysnomia that circles the dwarf planet every 16 days. In Greek mythology, Dysnomia is the name of one of Eris’s daughters and means “anarchy.”

5. Initially, Eris was called Xena.

Before it was called Eris, it was called 2003 UB313 (a provisional designation by the International Astronomical Union). But before that, Brown’s team of astronomers named it Xena—yes, of Warrior Princess fame. “We always wanted to name something Xena,” Brown told The New York Times in 2005 after the discovery. Among Brown’s colleagues, Dysnomia was called Gabrielle, who was, of course, Xena’s sidekick.

6. Its surface is like Pluto's heart.

The primary way to analyze the composition of the surface of a celestial body is through spectroscopy, which is basically looking at an object and seeing how much light comes back at you as a function of wavelength. Many materials have characteristic absorptions of light at certain frequencies, and so less light will come back to you at that frequency.

“Eris has very, very strong methane ice absorption bands,” Will Grundy, a planetary scientist at Lowell Observatory and a member of the New Horizons team, tells Mental Floss. “They are much stronger than Pluto’s, and of course we’ve seen methane all over the place on Pluto, so I think it’ll be more ubiquitous on Eris’s surface.” The implication is that Eris is more than just a dead ice rock in space, because methane degrades very quickly in a space environment, darkening and forming heavier hydrocarbons. “The fact that it’s bright and covered with methane ice says it’s refreshing its surface relatively rapidly, and there are any number of ways it can do that. One is the methane just periodically sublimates underneath the atmosphere and then re-condenses somewhere else, just sort of painting on top of whatever dark stuff that forms,” Grundy says.

7. Pluto data enriches our understanding of Eris.

Pluto data returned from the New Horizons spacecraft give scientists new ideas about the processes that might be at work on Eris. “One of the things the Pluto flyby showed us that nobody really talked about, even in wild speculations, was something like Sputnik Planitia: this big, bright, teardrop-shaped region on the encounter hemisphere. Volatile ices there are trapped in a deep basin and they are just convectively overturning, like a simmering pot of soup,” Grundy says.

That process might be happening writ large on Eris. It might be, in a sense, an ice lava lamp planet. “I’ve called it a Sputnik planet,” Grundy says, “but nature is much more clever than scientists at coming up with new ways of doing things with the same old ingredients. Who knows, we might get there and find out it’s doing something completely different than Pluto was doing to refresh its surface. The real lesson is that activity on a lot of different timescales is possible, even on a tiny little planet that’s at frigid temperatures, far away from the sun.”

8. Its neighborhood is a potential gold mine of information.

In comparative planetology, scientists use planets to understand other planets. By studying Venus, which is similar to Earth in terms of size, mass, and basic composition, scientists can better understand how our planet operates and evolved. The objects in Eris’s celestial neighborhood work the same way. “The Kuiper Belt”—a region rich in rocky and icy objects beyond Neptune’s orbit—“is an incredibly rich environment for comparative planetology because there are so just many of these tiny planets out there,” Grundy says. “It’s going to take a while to discover them all, let alone explore them all, but that’s what is exciting about it.” The New Horizons data from Pluto are helping planetary scientists develop models to tease out the secrets of Eris.

9. Geologists could learn a lot, too.

“If you work out the surface area of, say, objects there that are bigger than 100 kilometers, based on extrapolation, the Kuiper Belt has more solid geology surface area than of all of the planets in the solar system—including the terrestrial planets—combined,” Grundy explains, adding that it holds true even if you wanted to include the ocean floor on Earth. “If you like geology—and especially if you like exotic, cryogenic temperature geology—this is the place to explore, and there’s just so much territory to explore out there.”

10. A mission to Eris will take a while.

It took New Horizons, one of the fastest spacecrafts ever built, nine years to get to Pluto. Eris is currently three times farther from the Sun than Pluto (though due to a highly elliptical orbit, this number changes), so if a mission is ever approved, don’t expect to find out how it all ends. “It takes decades to pull something like that together, so if you want to be around to see the results, you’ve got to start young,” Grundy says. A possible future Kuiper Belt mission might be part of a flyby mission to Uranus or Neptune, after which the spacecraft would continue into that region of space. It will be a very long time before technology allows an Earth-centric telescope—in space or otherwise—to take pictures of the geology of Eris.

This Cool T-Shirt Shows Every Object Brought on the Apollo 11 Mission

Fringe Focus
Fringe Focus

NASA launched the Apollo 11 mission on July 16, 1969, ending the space race and beginning a new era of international space exploration. Just in time for the mission's 50th anniversary this year, Fringe Focus is selling a t-shirt that displays every item the Apollo 11 astronauts brought with them to the Moon.

The design, by artist Rob Loukotka, features some of the iconic objects from the mission, such as a space suit and helmet, as well as the cargo that never made it to primetime. Detailed illustrations of freeze-dried meals, toiletries, and maintenance kits are included on the shirt. The artist looked at 200 objects and chose to represent some similar items with one drawing, ending up with 69 pictures in total.

The unisex shirt is made from lightweight cotton, and comes in seven sizes ranging from small to 4XL. It's available in black heather or heather midnight navy for $29.

If you really like the design, the artwork is available in other forms. The same illustration has also been made into poster with captions indicating which pictures represent multiple items of a similar nature.

The International Space Station Will Start Accepting Visitors … For $58 Million

iStock/forplayday
iStock/forplayday

If you've ever wanted to visit the International Space Station, your chance is coming soon—assuming you have a few million set aside. Recently, NASA announced that this orbiting outpost will be open to private citizens starting in 2020.

However, it won't be cheap. According to The Denver Post, each trip could last up to 30 days, and NASA estimates the cost of a round trip at $58 million, as well as an additional $35,000 charge per night. And, it's not just for kicks—you need to have a mission of your own. The space agency is allowing companies that want to conduct commercial or marketing work to send employees to the ISS as long as they meet one of the three requirements:

  • require the unique microgravity environment to enable manufacturing, production, or development of a commercial application;
  • have a connection to NASA's mission; or
  • support the development of a sustainable low-Earth orbit economy

The space station had a visitor back in 2001—Californian businessman Dennis Titobecame history's first space tourist when he spent a week aboard the ISS with two Russian cosmonauts who took him out there on a Russian spacecraft—but this would be a first for NASA. The agency was opposed to training and flying with Tito back in 2001; at the time, NASA administrator Daniel Goldin said, "Space is dangerous. It's not a joyride. Space is not about egos."

Now, NASA is ready to open the shuttle doors to private citizens. In addition to U.S. citizens, those from other countries are eligible to travel as long as they fly on a U.S.-operated rocket. These lucky private astronauts will have to go through the same medical checks, physical training, and certification procedures as crew members before traveling—a process that could take up to two years.

Along with this exciting news, NASA has bigger plans in mind. They are considering the possibility of a private sector company eventually taking control of the station and paying for its expensive upkeep. NASA has yet to announce when this transition would take place, but said in a statement that the "ultimate goal in low-Earth orbit is to partner with industry to achieve a strong ecosystem in which NASA is one of many customers purchasing services and capabilities at lower cost."

In addition, they hope that the revenue will assist in the operational costs for NASA's Artemis program, which is focused on sending astronauts—including the first woman—to the Moon by 2024.

[h/t The Denver Post]

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