Space is big. Like, really big. You’ve probably heard that before, but it doesn't actually hit home until you start looking at a map of the outer solar system and realize that Pluto—the tiny ball of ice we used to call the ninth planet—is practically a next-door neighbor compared to Eris. If you’re wondering how far is Eris from the sun, prepare to feel very small.
Right now, in 2026, Eris is sitting way out there at roughly 95 astronomical units (AU) from the sun. To put that in perspective, one AU is the distance between the Earth and the sun. So, Eris is currently about 95 times further away from our star than we are. In miles? We’re talking nearly 8.9 billion miles. It’s so far that if you were standing on its frozen surface, the sun wouldn't look like a glowing orb; it would look like a particularly bright, piercingly white star in a pitch-black sky.
The Wild Orbit: Why Eris Isn't Always That Far
The thing about Eris is that it doesn't just sit in a nice, neat circle. Its orbit is what astronomers call "highly eccentric." Basically, it’s a giant, stretched-out oval.
Because of this weird path, the answer to how far is Eris from the sun changes drastically depending on when you ask. At its absolute closest point (perihelion), Eris sneaks in to about 38 AU. That’s roughly 3.5 billion miles. At that point, it’s actually closer to the sun than Pluto is at Pluto's furthest point. But don't get too excited about a visit; Eris spends most of its time way out in the "scattered disk," a graveyard of icy rocks beyond the Kuiper Belt.
When it swings out to its furthest point (aphelion), it reaches a staggering 97.6 AU, or about 9.1 billion miles. It’s currently heading toward that far point, moving at a glacial pace.
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A Year That Lasts Centuries
Because Eris has to travel such a massive distance in its orbit, its "year" is legitimately exhausting to think about. It takes Eris about 557 to 561 Earth years to complete one single trip around the sun.
Think about that. The last time Eris was in the same spot in its orbit as it is today, the Renaissance was just getting started in Europe. We hadn't even "discovered" the Americas yet. Entire empires have risen and fallen in the time it takes this one dwarf planet to make a single lap.
Sunlight Is Basically A Time Traveler
You know how it takes about 8 minutes for sunlight to reach Earth? By the time that same light reaches Eris, it’s been traveling for over 13 hours.
If the sun suddenly went out, we’d know in less than ten minutes. The hypothetical inhabitants of Eris wouldn't notice a thing until the next day. This extreme distance also means Eris is unimaginably cold. We’re talking -400 degrees Fahrenheit. At these temperatures, the air literally freezes and falls to the ground like snow.
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How Far Is Eris From The Sun Compared To Pluto?
This is where the drama started. Back in 2005, when Mike Brown and his team at Palomar Observatory officially announced the discovery of Eris (originally nicknamed "Xena"), it sent the world of astronomy into a tailspin.
Eris is roughly the same size as Pluto, but it’s about 27% more massive. Because it was so big and so far away, it forced everyone to ask: is this the 10th planet? If it’s not a planet, then what is Pluto?
- Pluto's Average Distance: ~39 AU
- Eris's Average Distance: ~68 AU
- The Gap: On average, Eris is nearly twice as far as Pluto.
Ultimately, the International Astronomical Union (IAU) decided to create the "dwarf planet" category in 2006. Eris didn't just break the rules; it changed the map of the solar system forever. Honestly, it’s kind of the reason Pluto got demoted. Sorry, Pluto fans.
Why We Can Barely See It
Even though Eris is huge for a dwarf planet, seeing it is a nightmare. It’s currently sitting in the constellation Cetus. Because it’s so far away, it’s incredibly dim—shining at a magnitude of about 18.7. You can't see it with your backyard telescope unless you've got some serious professional-grade gear and a lot of patience.
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Most of what we know comes from "occultations." This is when Eris passes in front of a distant star, briefly blocking its light. By timing how long the star disappears from different locations on Earth, scientists can calculate Eris’s size and shape with incredible precision. It’s a bit like trying to measure a marble in New York by watching it pass in front of a candle from a window in Los Angeles.
The Lone Companion: Dysnomia
Eris isn't out there alone. It has a moon named Dysnomia. Named after the daughter of the Greek goddess Eris, Dysnomia helps us calculate Eris’s mass. By watching how fast the moon orbits the dwarf planet, we can "weigh" Eris. It turns out Eris is quite rocky, likely because it’s so dense.
What This Means For Future Exploration
Will we ever send a probe to Eris? Probably not anytime soon.
NASA’s New Horizons took nine years just to get to Pluto. To reach Eris at its current distance, a similar craft would need to travel for nearly 30 years. Unless we come up with some radical new propulsion technology, Eris will remain a distant, icy mystery for the foreseeable future.
If you’re interested in tracking Eris yourself, you should look into professional star charts or apps like Stellarium. While you won't see a disk, knowing that a tiny speck of light 9 billion miles away is actually a world larger than the Asteroid Belt is pretty mind-blowing.
Next Steps for You:
If you want to dive deeper, I recommend looking up the New Horizons 2 mission proposals—even though they were never funded, the flight paths they planned for Eris are fascinating. You can also check out Mike Brown’s book, How I Killed Pluto and Why It Had It Coming, for the full "behind-the-scenes" story of the discovery that redefined our solar system.