Pluto: Why It’s No Longer a Planet — and Everything Else to Know

By Hamza — astrophotographer since 2008, imaging from a remote dark-sky rig at Deepsky Chile.

Quick answer: Is Pluto a planet? No — Pluto is a dwarf planet. The International Astronomical Union (IAU) reclassified it on August 24, 2006, because it fails one of the three planet rules: it has not cleared its orbital neighborhood. Pluto still orbits the Sun and is round, but it shares its space with countless icy bodies in the Kuiper Belt.

Pluto is the most famous “demoted” world in the solar system, and the question “is Pluto a planet?” still sparks arguments at dinner tables, in classrooms, and even at NASA. The short version: for 76 years Pluto was counted as the ninth planet, but in 2006 astronomers agreed on a strict definition of the word planet for the very first time — and Pluto did not make the cut. It became the best-known member of a category called dwarf planets, joining worlds like Eris, Ceres, Haumea, and Makemake.

This guide answers every common Pluto question in plain language, then goes somewhere almost no other page does: how to actually find and photograph Pluto yourself. You will get the answer-first verdict, the full reclassification story (including the live 2026 “make Pluto a planet again” debate), a scannable quick-facts table, the truth about its size compared to the Moon, its five moons, what the New Horizons flyby discovered in 2015, and a hands-on observing section drawn from my own nights chasing this faint, star-like world through the eyepiece and the camera.

Pluto sits far out in the Kuiper Belt, the ring of frozen leftovers beyond Neptune, which is exactly why it never swept its lane clean. For the bigger picture of how Pluto fits among its icy siblings, see our complete guide to dwarf planets in the solar system, part of the broader Solar System hub. If you are mainly here to settle the planet debate once and for all, keep reading — the next section breaks down the three IAU rules one by one.

Table of contents

1. Is Pluto a planet?
2. Why is Pluto not a planet anymore?
3. Will Pluto ever be a planet again?
4. Pluto facts: size, distance, orbit and temperature
5. Pluto’s moons: Charon and the rest
6. What New Horizons revealed (2015)
7. How Pluto was discovered
8. How to see and photograph Pluto
9. Frequently asked questions

Is Pluto a planet?

No. Pluto is not one of the eight planets. Since August 24, 2006, the International Astronomical Union (IAU) has classified Pluto as a dwarf planet — a real category of its own, not a “fake” planet. It still orbits the Sun and it is still round. It simply does not meet every rule the IAU uses to define a full-fledged planet.

To count as a planet under IAU Resolution 5A, a body must pass all three of these tests:

Pluto sails through the first two with no trouble. It is the third rule it fails — and that single failure is the entire reason it is a dwarf planet instead of a planet.

What does “clearing the neighborhood” mean? A true planet is the gravitational boss of its orbital lane. Over billions of years, it has swept up, flung away, or captured nearly every other object near its path, so it orbits more or less alone. Earth has done this. So has Neptune. Pluto has not. It lives inside the Kuiper Belt, a vast ring of icy bodies beyond Neptune, and it shares that space with countless similar objects. In fact, Pluto’s mass is only a tiny fraction of the other material sharing its orbital zone, so its gravity is far too weak to dominate that crowd — it has never become the master of its own orbit.

Think of it this way: a planet is like the only large fish in its stretch of river. Pluto is one fish among thousands of others near its size — it just happens to be one of the bigger ones in a very crowded zone.

What is a dwarf planet, exactly?

A dwarf planet is a body that is round (its own gravity has pulled it into a sphere) and orbits the Sun, but has not cleared the other objects out of its orbital path. That last part is the whole difference between a dwarf planet and a planet. Dwarf planets are also not moons — they orbit the Sun directly, not another world.

The IAU currently recognizes five official dwarf planets:

Notice the pattern: four of the five dwarf planets live in the cold, crowded trans-Neptunian region beyond Neptune. Ceres is the lone exception — it sits much closer to us in the asteroid belt. So it is a common mistake to think every dwarf planet is a Kuiper Belt object; Ceres breaks that rule.

That is why the answer to both “is Pluto a planet?” and “is Pluto a dwarf planet?” is the same: Pluto is a dwarf planet, and the largest one out in the Kuiper Belt. To see how it stacks up against the others, visit our full guide to the solar system’s dwarf planets, and explore where Pluto fits within the wider Solar System hub.

Why is Pluto not a planet anymore?

Pluto is not a planet anymore because, in 2006, astronomers wrote the first official definition of the word “planet” — and Pluto did not meet all of it. Pluto stopped being a planet on August 24, 2006, the day the International Astronomical Union (IAU) passed Resolution 5A on the definition of a planet at its General Assembly in Prague.

The whole thing started with a discovery. In 2005, astronomer Mike Brown and his team announced Eris, a distant icy world out past Neptune. Eris was roughly the same size as Pluto, and it was actually more massive — about 27% heavier. That created a problem nobody could ignore: if Pluto counts as a planet, then Eris has to count too — and so do the other Pluto-sized objects astronomers were starting to find in the same region. Either the solar system was about to gain a 10th, 11th, and 12th planet, or the word “planet” needed a real, agreed-upon meaning. (Eris was the trigger for the whole debate, and it gets its own page in our look at Eris, the dwarf planet that demoted Pluto.)

So the IAU set three tests. To be a full planet, an object must:

Pluto passed the first two easily. It failed the third — and that one rule is the entire reason for its demotion.

What does “clearing the neighborhood” mean? It means a planet has to be the gravitational boss of its orbit. Over billions of years, a true planet either sweeps up the smaller objects near its path, flings them away, or locks them into orbit as moons. The result is a clean lane with one dominant body. Earth has done this. So has Neptune.

Pluto has not. It lives in the Kuiper Belt, a crowded ring of countless icy bodies beyond Neptune, and it shares that broad trans-Neptunian region with many neighbors — including Eris, which orbits even farther out in the scattered disc. Pluto simply isn’t massive enough to dominate its surroundings; for comparison, Earth outweighs everything else in its orbital zone by about 1.7 million times, while Pluto barely outweighs the debris around it. Because it shares its lane instead of ruling it, Pluto became a dwarf planet rather than a planet. You can read more about its crowded home region in our guide to the Kuiper Belt and trans-Neptunian objects.

Who actually decided this — and was it fair? The vote was made by the IAU, the only body with the authority to officially name and classify objects in space. But the decision was contentious. It happened on the final day of a roughly two-week meeting, after many attendees had already left, so only 424 astronomers — a small fraction of the IAU’s roughly 9,000 members — actually cast a ballot. Critics still point to that small turnout as a reason the result feels unsettled. Some astronomers — most vocally New Horizons lead scientist Alan Stern — argued the definition was flawed and never accepted it. That disagreement is exactly why the “is Pluto a planet?” question still flares up today. But as a matter of official record, the answer has not changed since 2006: Pluto is a dwarf planet. For the bigger picture, head back up to the Solar System hub or the parent guide to the dwarf planets of the solar system.

Will Pluto ever be a planet again?

Short answer: not officially, and no reversal is expected anytime soon. Pluto is still a dwarf planet under the only definition that counts for scientific naming — the International Astronomical Union’s (IAU) 2006 ruling. The IAU has never revisited or reversed that vote, and as of 2026 it has given no signal that it plans to. So while the argument is very much alive in public, Pluto’s status on the books has not changed.

That said, the debate is real, and serious scientists are on the “planet” side.

The competing “geophysical” definition. New Horizons mission lead Alan Stern and a group of planetary scientists reject the IAU rule and back a geophysical planet definition instead. Their idea is simple: if a body in space is big enough that its own gravity pulls it into a round (or nearly round) shape, and it is not a star, it is a planet. Under that “round = planet” test, Pluto qualifies easily — and so would dozens of other worlds, including large moons like our own Moon.

Why they say the IAU definition is flawed. Critics make a few recurring arguments:

Supporters of the IAU rule counter that “orbital dominance” is exactly what separates the eight major planets from the swarm of smaller Kuiper Belt bodies — and that a definition giving us 100-plus planets would be far less useful for teaching and science. (See how this plays out in the three IAU planet criteria and what “clearing the neighborhood” really means.)

Public and political pushback. Roughly every few years the topic flares up again — in op-eds, at conferences, in state legislatures (New Mexico in 2007 and Illinois in 2009 symbolically “kept” Pluto a planet), and most recently in late April 2026. Testifying before a U.S. House Appropriations subcommittee on April 28, 2026, NASA Administrator Jared Isaacman said he is “very much in the camp of ‘make Pluto a planet again.'” He added that NASA is “doing some papers right now” on a position it would “love to escalate through the scientific community to revisit this discussion” — and tied the effort to making sure Clyde Tombaugh, Pluto’s discoverer, “gets the credit he received once and rightfully deserves to receive again.” These moments generate headlines, but none carries the authority to change anything. Only the IAU can redefine “planet,” and it has not moved.

For most planetary scientists, the honest takeaway is this: the label is a human convention, but Pluto itself — a complex, geologically active world with mountains, glaciers, and a possible subsurface ocean — is fascinating regardless of which box we file it in. Explore where it sits among the other dwarf planets, the world whose discovery Eris triggered the whole debate, and the wider Solar System.

Pluto facts: size, distance, orbit and temperature

Here is the fast version of Pluto by the numbers. Every figure below is rounded to the values most scientists use today, drawn from NASA and New Horizons data.

How big is Pluto? Pluto is about 2,377 km (1,477 mi) across. That sounds large until you compare it to home. Pluto is smaller than Earth’s Moon and only about two-thirds the Moon’s width. It is roughly one-fifth the diameter of Earth. If Earth were a basketball, Pluto would be about the size of a golf ball. Its small size and shared orbit are the reasons it sits in the dwarf-planet club rather than with the major planets.

Pluto vs the Moon (size at a glance):

So Pluto is roughly two-thirds the width of our own Moon — a fact that surprises almost everyone, because for decades we pictured it as a full-sized ninth planet.

How far is Pluto? On average, Pluto orbits about 39.5 AU from the Sun. One AU (astronomical unit) is the Earth-Sun distance, so Pluto sits roughly 39.5 times farther out than we do — about 5.9 billion km (3.7 billion mi). Its orbit is also stretched and tilted, swinging from 29.7 AU at its closest to 49.3 AU at its farthest. For about 20 years (1979 to 1999) this carried Pluto inside Neptune’s orbit, making it temporarily the eighth-most-distant body from the Sun. Sunlight is so weak out there that noon on Pluto looks like deep twilight on Earth, and that same faintness is why you need real aperture to spot it (see the observing and astrophotography section below).

How cold is Pluto? Brutally cold. Surface temperatures average around -229°C (-380°F), just 44 degrees above absolute zero, and across the globe they run roughly -226°C to -240°C (-375°F to -400°F). At that chill, gases we breathe freeze solid — Pluto’s “snow” and surface frost are nitrogen, methane and carbon-monoxide ice. The temperature is not fixed, though. Because Pluto’s orbit is so eccentric, it warms slightly near closest approach and cools as it retreats. That swing drives a remarkable cycle: Pluto’s thin nitrogen atmosphere puffs up when it is nearer the Sun and partly freezes back onto the surface as it moves away. Pluto reached its closest point to the Sun (perihelion) back in 1989 and has been slowly receding ever since, heading toward its farthest point (aphelion) around the year 2113. Because it is moving outward the whole time, Pluto is expected to keep cooling and its atmosphere to keep thinning for decades to come.

A quick orbital oddity worth knowing: Pluto’s ~248-year trip around the Sun never actually crashes into Neptune. The two are locked in a 3:2 orbital resonance — Pluto completes two laps for every three Neptune makes — which keeps them safely out of each other’s way. You can place Pluto in its deep-freeze home region in the guide to trans-Neptunian objects and the Kuiper Belt, or step back up to the full dwarf planets guide and the Solar System hub for the bigger picture.

Pluto’s moons: Charon and the rest

Pluto has five known moons. From largest to smallest, they are Charon, Hydra, Nix, Kerberos, and Styx. Charon is by far the biggest; the other four are small, lumpy worlds discovered between 2005 and 2012, in the run-up to the New Horizons flyby.

Charon: about half the width of Pluto

Charon is so large compared to Pluto that the pair behaves almost like a double planet. Charon’s diameter is about 1,212 km (753 mi) — roughly half of Pluto’s 2,377 km (1,477 mi). No other moon in the solar system is anywhere near that big relative to the world it orbits. James Christy discovered it in 1978.

That size has a striking effect. The two bodies are mutually tidally locked, meaning each always shows the same face to the other. If you stood on the side of Pluto that faces Charon, the moon would hang frozen in the sky, never rising or setting. From the far side, you would never see Charon at all.

Stranger still, Pluto and Charon orbit a shared center of mass — the barycenter — that sits in empty space above Pluto’s surface, not deep inside Pluto. In every other planet–moon pair in our solar system, the barycenter lies inside the larger body, so the moon clearly circles the planet. Here, both worlds visibly swing around an external point. That is why many astronomers describe Pluto and Charon as a binary system.

The four small moons

The remaining moons are tiny, irregular, and oddly behaved. Rather than spinning smoothly, Nix and Hydra tumble chaotically as they orbit the shifting Pluto–Charon gravity field — Hubble observations showed they wobble so unpredictably that an observer would not see the same face twice.

All five names tie back to the Greek and Roman mythology of the underworld, fitting for a world named after its ruler. The four small moons are far too faint for backyard telescopes — even spotting Pluto itself is a real challenge, as covered in the observing Pluto section. For the wider family of icy worlds Pluto belongs to, see the guide to dwarf planets and the Kuiper Belt and trans-Neptunian objects.

What New Horizons revealed (2015)

For 85 years after Clyde Tombaugh found it, Pluto stayed a fuzzy dot. Even the Hubble Space Telescope showed only blurry patches of light and dark. That changed on July 14, 2015, when NASA’s New Horizons spacecraft raced past Pluto at about 49,600 km/h (30,800 mph) and gave us our first close-up look at this distant world. At closest approach, it came within about 12,500 km (7,800 mi) of Pluto’s surface.

What it found stunned everyone. Scientists expected a dead, cratered ball of ice. Instead, Pluto turned out to be a complex, active, planet-like world.

The headline discoveries

Cryovolcanism: a world that may still erupt

One of the most surprising finds was cryovolcanism — volcanoes that erupt icy slush instead of molten rock. The leading candidates are two enormous mounds south of the heart, Wright Mons and Piccard Mons, each roughly 160 km (100 mi) across and about 4 km (13,000 ft) high, with a deep central depression like a caldera. The bumpy, crater-poor ground around them looks like it was built by repeated outpourings of water-ice “lava” within roughly the last billion or two years — recent, in geological terms. If confirmed, it means Pluto still has internal heat, which strengthens the case for that hidden subsurface ocean.

A 2026 freshness note: Pluto’s haze “thermostat”

Pluto keeps making news. Recent observations with the James Webb Space Telescope (JWST) confirmed that Pluto’s high-altitude haze — those blue layers New Horizons photographed — actually controls the dwarf planet’s climate. The tiny haze particles soak up sunlight by day and radiate heat away at night, cooling Pluto’s upper atmosphere far more than its gases alone could (by roughly 30°C more than older models predicted). Scientists call it a haze “thermostat,” and it appears to be unique in the solar system. It is a striking reminder that even a “demoted” world a few billion kilometers away is still teaching us new physics.

Why it rewrote what we knew

Before 2015, most people pictured dwarf planets as boring frozen rubble. New Horizons proved that small, far-off worlds can have flowing glaciers, towering mountains, layered skies, possible ice volcanoes, and maybe even hidden oceans. A body does not need to be a “real” planet to be fascinating and active.

The flyby also gave Pluto a face. The heart, the glacier, and the haze turned an abstract debate about classification into a real place people care about. That emotional pull feeds today’s renewed “make Pluto a planet again” arguments.

You can read NASA’s full mission story at the New Horizons mission page and NASA’s Pluto overview. For more on the icy region Pluto calls home, see our guide to trans-Neptunian objects and the Kuiper Belt, and head back up to the dwarf planets overview to see how Pluto compares with its siblings.

How Pluto was discovered

Clyde Tombaugh discovered Pluto on February 18, 1930, at Lowell Observatory in Flagstaff, Arizona. He was a 24-year-old farm boy from Kansas with no college degree, hired to do one tedious job: hunt for “Planet X.”

That search began with Percival Lowell. The wealthy astronomer was convinced an unseen ninth planet was tugging on the orbits of Uranus and Neptune, and he spent his final years predicting where it should be. Lowell died in 1916 without finding it. More than a decade later, the observatory he founded handed the hunt to Tombaugh.

Tombaugh’s method was slow and brilliant. He photographed the same patch of sky on different nights, then loaded pairs of plates into a blink comparator — a machine that flips back and forth between two images. Stars stay put; a planet shifts position. On February 18, 1930, Tombaugh compared two plates taken in January 1930 (on the 23rd and the 29th) and spotted one faint speck that jumped between them. He had found a new world far beyond Neptune.

The name came from an 11-year-old English schoolgirl, Venetia Burney. Over breakfast, she suggested “Pluto,” the Roman god of the underworld — a fitting title for a dark, frozen world. Her grandfather passed the idea to Lowell Observatory, and it was made official on May 1, 1930. A nice bonus: the first two letters, PL, honor Percival Lowell’s initials. Walt Disney’s cartoon dog Pluto debuted later that same year, but the planet came first — the dog was almost certainly named after the headline-making discovery.

Tombaugh’s story has one last chapter. When he died in 1997, a small portion of his ashes was placed aboard NASA’s New Horizons spacecraft. On July 14, 2015, those ashes swept past Pluto — making Tombaugh the only person whose remains have traveled to a world he discovered. To explore where Pluto sits today, see our dwarf planets guide and the wider Solar System hub.

How to see and photograph Pluto

Pluto is hard. Right now it shines at only about magnitude 14.9–15 — and it sinks to magnitude ~15.0 around its July 2026 opposition — far too faint for your eyes alone or for binoculars. (The often-quoted “magnitude 14.4” is roughly its all-time brightest; at this point in its orbit, plan for fainter than that.) To have a realistic chance you want a 10-inch (250 mm) or larger telescope under genuinely dark skies. A skilled observer can sometimes pull Pluto out with an 8-inch (200 mm), but only under excellent, truly dark rural skies — treat 10–12 inches as the practical floor. Even then, do not expect a view of “the heart” or those icy mountains. Pluto never shows a disk. In any backyard telescope it looks exactly like a faint star: a single, dim point of light lost among thousands of others.

Observing difficulty: hard (expert). This is one of the toughest targets in the solar system for amateurs, mostly because Pluto hides in star-rich fields near the Milky Way and is dimming year by year as it recedes from the Sun. Remember the orbital picture from the facts section: Pluto passed perihelion in 1989 and is now heading outward toward aphelion around 2113, so it will keep fading for decades. In short, it is easier to catch now than it will be later — there is no reason to wait.

Because Pluto looks like every other faint star, the only way to prove you found it is to watch it move. Here is the method I use on my remote rig:

1. Plan the field. Pull a current finder chart or ephemeris — in 2026 Pluto sits in Capricornus — and aim for the weeks around opposition (about July 27, 2026), when Pluto is highest, closest, and at its best for the year.
2. Frame the star field. Use our FOV simulator to match your scope and camera to the exact patch of sky so Pluto lands cleanly on your sensor with reference stars around it.
3. Expose for a magnitude-15 dot. Pluto is faint, so each sub-exposure has to go deep without burning out the field stars. Our sub-exposure calculator helps you pick an exposure time that beats the read noise and sky glow. (Both tools live in the astrophotography calculator hub.)
4. Image two or more nights. Shoot the same field on at least two nights, 24+ hours apart.
5. Blink the frames. Flip between the aligned images. Every real star stays put; the one “star” that shifts position is Pluto. This blink-comparison trick is the same idea Clyde Tombaugh used to discover it in 1930, just with a screen instead of glass plates.

I confirm Pluto exactly this way from my dark-sky setup at Deepsky Chile (a 12.5-inch Ritchey-Chretien on a Paramount mount). The southern site and large aperture make the blink obvious within two clear nights. You can read more about that rig and my background on the about page. The payoff is not a pretty picture. It is the quiet thrill of catching a world 5.9 billion km (3.7 billion mi) away drifting against the stars with your own equipment.

Frequently asked questions

Is Pluto a planet?
No. Pluto is not a full planet. Since August 24, 2006, the International Astronomical Union (IAU) has classified Pluto as a dwarf planet. It is still a real, fascinating world — it just doesn’t meet all three of the IAU’s rules for a full-sized planet.

Why is Pluto not a planet?
Pluto fails one of the three IAU planet tests: it has not “cleared the neighborhood” around its orbit. A true planet is the gravitational boss of its orbital zone, but Pluto shares the Kuiper Belt with countless other icy objects. It passes the first two tests (it orbits the Sun, and it is round), but missing the third one is what makes it a dwarf planet.

When did Pluto stop being a planet, and who decided?
On August 24, 2006, at the IAU General Assembly in Prague. The IAU — the body that officially classifies objects in space — voted on Resolution 5A, which created the first official definition of a “planet,” and Pluto did not qualify. Only about 424 of the roughly 9,000 IAU members were present to vote, which is one reason critics still call the decision contested. Pluto had been counted as the ninth planet for 76 years, ever since its 1930 discovery.

Will Pluto become a planet again?
Maybe, but not yet. In late April 2026, NASA Administrator Jared Isaacman told a congressional hearing he is “very much in the camp of ‘make Pluto a planet again,'” and said NASA is working on papers to push the science community to revisit the question. Some scientists also favor a “geophysical” definition that would restore it. However, only the IAU can officially change the rules, and no vote has reversed the 2006 decision. As of 2026, Pluto remains a dwarf planet.

How big is Pluto?
Pluto is about 2,377 km (1,477 miles) across — roughly two-thirds (about 68%) the width of Earth’s Moon. That makes it smaller than the Moon, which spans 3,474 km (2,159 miles). It is the largest dwarf planet by diameter.

How far is Pluto from the Sun?
On average about 39.5 AU, or roughly 5.9 billion km (3.7 billion miles). Its orbit is very stretched, ranging from 29.7 AU at its closest to 49.3 AU at its farthest. From 1979 to 1999 it was actually closer to the Sun than Neptune.

How cold is Pluto?
Extremely cold — around −229°C (−380°F, or about 44 kelvin). At that temperature, gases like nitrogen and methane freeze solid into the ices that coat Pluto’s surface.

How long is a day and a year on Pluto?
A day on Pluto lasts about 6.4 Earth days (the time it takes to spin once, and it spins in a retrograde direction). A year — one full orbit around the Sun — takes about 248 Earth years.

How many moons does Pluto have?
Five. Charon is by far the largest (~1,212 km) and so big relative to Pluto that the two orbit a shared point in space, behaving almost like a binary system. The four small moons are Nix, Hydra, Kerberos, and Styx, all named from underworld mythology.

Why is it called Pluto?
An 11-year-old English schoolgirl named Venetia Burney suggested it in 1930, after Pluto, the Roman god of the underworld — a fitting name for a cold, dark, distant world. There was a bonus, too: the first two letters, “PL,” match the initials of Percival Lowell, the astronomer whose search led to the discovery. The name became official on May 1, 1930.

Is Pluto in the Kuiper Belt?
Yes. Pluto orbits within the Kuiper Belt, a vast ring of icy bodies beyond Neptune, and it is the largest known object there. Sharing that crowded region — rather than ruling it — is precisely why Pluto counts as a dwarf planet instead of a planet.

Does Pluto have an atmosphere and an ocean?
Yes to a thin atmosphere, and maybe to an ocean. Pluto has a thin atmosphere of mostly nitrogen, with some methane and carbon monoxide, that expands when Pluto is nearer the Sun and partly freezes onto the surface as it moves away. New Horizons also found evidence that a liquid water ocean may lie hidden beneath Pluto’s icy crust, kept from freezing by internal heat — though that subsurface ocean is still considered likely rather than proven.

What is Pluto made of?
Pluto is a mix of about two-thirds rock and one-third ice. Its surface is coated in frozen nitrogen, methane, and carbon monoxide, with mountains of hard water-ice. New Horizons even found hints of a possible liquid water ocean beneath the icy crust.

Who discovered Pluto?
American astronomer Clyde Tombaugh discovered Pluto on February 18, 1930, at Lowell Observatory in Arizona, using a blink comparator to spot its motion. It was named by 11-year-old Venetia Burney, after the Roman god of the underworld.

Has a spacecraft ever visited Pluto?
Yes. NASA’s New Horizons probe flew past Pluto on July 14, 2015, passing about 12,500 km (7,800 miles) above its surface. It revealed the bright, heart-shaped Tombaugh Regio, the vast Sputnik Planitia nitrogen-ice glacier, towering water-ice mountains, possible ice volcanoes, and a hazy, layered atmosphere.

Can you see Pluto with a telescope?
Yes, but it’s a serious challenge. Pluto shines at only about magnitude 14.9–15 (around magnitude 15.0 at its July 2026 opposition). In practice you’ll want a 10-inch (250 mm) or larger telescope under truly dark skies — an 8-inch can reach it only in excellent conditions — and even then it looks like a faint star with no disk. You confirm it by photographing or sketching it over several nights and watching it drift against the background stars. (Our observing-and-astrophotography guide above walks through the full method.)

Is Pluto bigger than Eris?
It depends on how you measure. Pluto is slightly larger in diameter (~2,377 km vs. Eris’s ~2,326 km), but Eris is about 27% more massive. Eris’s discovery in 2005 is what triggered the whole “what is a planet?” debate — you can read more on our Eris dwarf planet page.

Written by Hamza, an astrophotographer imaging the night sky since 2008. I chase faint targets like Pluto from a remote rig at Deepsky Chile — a 12.5-inch Ritchey-Chretien on a Paramount MX+ mount — and share the results on Instagram @stellar.nomads. More about my setup and approach is on the about page.

Ready to hunt Pluto yourself? Plan the exact star field with the FOV simulator, dial in your exposure with the sub-exposure calculator, and find every other tool you need in the astrophotography calculator hub. Then keep exploring: head back up to the dwarf planets guide, the main Solar System hub, or the Kuiper Belt and trans-Neptunian objects guide.