Can You Really See Mallorca From Barcelona? The Exact Geometry of a 190 km Sightline

Photo: Doc Searls, CC BY 2.0, via Wikimedia Commons.

On certain cold November mornings, people standing on Barcelona's hills photograph a jagged blue silhouette floating on the sea horizon to the south-southeast, backlit by the low dawn sun. The silhouette is the Serra de Tramuntana, the mountain spine of Mallorca, about 190 km away. Every time one of these photos circulates, the same argument starts underneath it. A lot of the city simply does not believe it. The photographer who has documented the sightline most carefully, Marc Bret, wrote after one of his own sightings that "despite this sightings a large ammount of citizens from Barcelona still don't believe Mallorca can actually be seen from its city."

Photo: candi… on Flickr, CC BY 2.0.

And on the very best mornings the apparition needs no squinting at all. In December 2023 the Fabra Observatory's meteorologist, Alfons Puertas, caught the whole Tramuntana in crisp silhouette against the dawn, floating over the lights of Barcelona's port:

The disbelief got international help a few weeks before that tweet, in November 2023, when Puertas photographed Mallorca at dawn from the same terrace and the press reported the image as one that "defies science", on the reasoning that Earth's curvature should hide the island entirely. The only explanation on offer was a tweet gesturing at "atmospheric refraction."

Nobody in that argument had run the terrain. The people who believe cite photos, the people who don't cite the curvature of the Earth, and the one attempt at rigor relies on panorama simulators. So we ran it: every sightline from six real places in Barcelona to six summits across Mallorca, through 30 m elevation data, with curvature and refraction in the geometry, plus a sweep to find the exact minimum height you need and the exact amount of bent air each disputed sighting requires.

The short version: the believers are right, the sceptics have the physics backwards, and the famous "impossible" photo is two different phenomena wearing one caption.

What we ran

Everything below comes from the same engine that powers UpToWhere, working on the 30 m Copernicus elevation model with Earth's curvature and atmospheric refraction built into the geometry. Standard refraction bends light gently downward over long paths; the textbook coefficient for ordinary air is k = 0.13, and that is what "standard" means everywhere in this article. We computed:

• Point-to-point sightlines from six real Barcelona observers (the Tibidabo summit at 512 m, the Fabra Observatory at 415 m, the Bunkers del Carmel at 262 m, two spots on Montjuïc, and the Barceloneta seafront) to six targets spanning the whole island silhouette: Puig Major (1,436 m), Puig de Massanella (1,364 m), the Teix (1,064 m), Puig de Galatzó (1,027 m), the crest of the Formentor peninsula (about 420 m) and the island of Sa Dragonera (353 m).
• A refraction sweep on every blocked line, to find the exact coefficient at which each hidden summit would appear, separating "needs slightly unusual air" from "needs a small miracle."
• A minimum-height search at the seafront: the lowest eye level, in metres above the sea, from which Puig Major clears the horizon under standard refraction.
• The reverse direction, from the summit of Puig Major back toward Barcelona.

From Tibidabo, three summits clear the horizon

Start from the city's classic high point, the 512 m summit of Tibidabo, where Bret took his 184–193 km photographs in November 2014. Under standard refraction, with no anomaly of any kind, the engine finds three separate pieces of Mallorca standing above the sea horizon:

Photo: NASA, ISS064-E-406, public domain, via Wikimedia Commons.

That table scores the exact summit points. For the full picture we also swept the whole horizon, one computed ray every half degree: the island shows as a serrated skyline running from bearing 157° to 172°, fifteen degrees of horizon, with the Puig Major and Massanella wall at its centre, the ridge of the Teix to its right, Galatzó's lone tip at the right edge, and stretches of open sea between them where the island's lower terrain stays buried below the horizon. That is exactly how observers have always described the apparition, and Bret's post says it plainly: the mountains appear "discontinuously, with some mountains separated between them by the sea." The folk description and the computed geometry agree in detail.

Photo: Joan Gené, CC0, via Wikimedia Commons.

The Teix deserves its own sentence. Its exact summit point misses by ten centimetres over a 193 km path, far inside the noise of a 30 m elevation model, so honestly the summit is neither visible nor hidden; it sits exactly on the horizon line. The ridge it anchors above Sóller shows up regardless: the half-degree sweep finds its seaward crest standing a couple of hundred apparent metres out of the sea at bearing 166°.

And note what happens a few hundred metres down the ridge. From the Fabra Observatory, 100 m lower than the summit, the Teix clears comfortably (by 28 m) while Galatzó drops out (31 m short, needing k ≈ 0.15). Two viewpoints on the same Barcelona hill, a few minutes' walk apart, see two different Mallorcas. At clearances this thin, every metre of observer height and every step along the ridge redraws the silhouette.

The sea is not the obstacle. The island is

Here is the counterintuitive part. From Tibidabo, the sightline to Puig Major clears the open sea with hundreds of metres to spare. What nearly blocks it is Mallorca itself.

The last obstacle on the way to the summit is Puig Major's own seaward shoulder, a 1,170 m ridge about 600 m in front of the peak; the summit clears it by just 15 m. And the horizon ray itself cuts the island at roughly the 700 m contour. Everything below that altitude, the ports, the towns, nearly the entire coastline, stays buried behind the curve of the sea, while the crests above it stand clear. The tallest sea cliffs of the Tramuntana's seaward wall, which reach roughly 700 m where the range plunges into the water below Puig Major, sit almost exactly on the line, appearing and vanishing with the day's refraction. So the image that reaches Barcelona is a horizontal slice: the upper half of a mountain range, floating with no visible base.

Photo: Joan Gené, CC0, via Wikimedia Commons.

This is also why the apparition floats. Earth's curvature drops the far end of a 188 km sightline by about 2,400 m; after the observer's height and the horizon geometry net out, the island's lowest visible altitude from Tibidabo works out to about 700 m. Of Puig Major's 1,436 m, Barcelona receives roughly the upper half, and of the island as a whole almost nothing. Our article on how much the horizon hides walks through that arithmetic for any distance.

How low can you stand and still see it?

Tibidabo is comfortable. The interesting question is the threshold, and the folk claims are surprisingly specific. Bret reported seeing the island from just 95 m up on Montjuïc, and referenced another observer's sighting from 52 m under "exceptional refraction."

So we searched for the threshold directly: at the Barceloneta seafront, facing Puig Major 181 km away, the engine flips from hidden to visible between 91 and 93 m of eye height under standard refraction. Call it 92 m.

Now put the folk claims against that number:

• The 95 m sighting works with three metres to spare. The lowest documented observation of Mallorca from Barcelona sits almost exactly on the computed geometric threshold. Bret was not exaggerating his luck; he was standing at the exact height where the island is born.
• The 52 m claim needs k ≈ 0.21, about sixty percent more bend than standard air. That is a strong but entirely real condition, the kind cold mornings over a warm sea produce. The claimant called it exceptional refraction, and the number agrees with the adjective.
• A point on Montjuïc's seaward slope at 86 m just misses: k = 0.132, a whisker above standard, tips it over. On that slope, on any slightly favourable morning, the summit is there.
• From the castle esplanade at the top of Montjuïc's 173 m hill, Puig Major clears under plain standard air.
• From the beach itself, standing at the waterline, it never works. The refraction needed is k ≈ 0.74, deep ducting territory; at that point you are seeing a mirage more than a mountain.

The city's own favourite miradors sort themselves neatly around these numbers. The Bunkers del Carmel, at 262 m the city's best-loved sunset terrace, sees both giants comfortably: Puig Major clears by 27 m at 187 km, Massanella by 50 m at 189 km, matching the 189 km sightline fan on its featured page. Everything lower on the island needs helped air from up there: the Teix at k ≈ 0.19, Galatzó at k ≈ 0.27, Sa Dragonera at k ≈ 0.64.

The "impossible" 2023 photo, split into its two parts

The Fabra Observatory photograph that "defies science" contains two different sightings, and they deserve separate verdicts.

The first is the mountain silhouette. From Fabra at 415 m, Puig Major clears the horizon by 47 m and Massanella by 50 m under standard refraction. (More margin, oddly, than the summit 100 m above it gets: each ray crosses a different notch of the island's own foreground ridge, and Fabra's notch happens to sit lower.) No anomaly, no mirage, no defiance of anything. A meteorologist photographing Mallorca's summits from that terrace on a clear November dawn is photographing ordinary, permanent geometry that most of the city happens not to know about.

The second is genuinely extraordinary, and the press coverage never noticed it was the interesting part. The photo shows the lights of Port de Sóller, a harbour at sea level. A sea-level target 187 km away is a completely different problem from a 1,436 m summit: our sweep says those lights need k ≈ 0.8 to reach Fabra, five or six times the standard bend. That is not everyday refraction; that is a strong thermal duct hugging the sea surface and piping light around the curve, the same mechanism that occasionally shows Chicago's skyline across Lake Michigan. The summits in that photograph are geometry. The harbour lights are weather, and rare weather at that.

So "defies science" was exactly wrong, twice. The part presented as impossible is routine, and the part nobody remarked on is the real anomaly, precisely quantifiable as such.

Can Mallorca see Barcelona back?

Strictly yes, and it has to, because a sightline is reversible: if your eye on Tibidabo catches light from Puig Major's summit, an eye on that summit catches light from yours along the exact same ray. The engine agrees to within its grid. Tibidabo sees Puig Major with 15 m to spare; Puig Major sees Tibidabo's summit with about 4 m. (The small difference is bookkeeping, the 1.7 m eye height and the 30 m terrain cells swapping ends, not physics.)

What is not symmetric is the scenery, because the two shores stack their mass at very different altitudes. The grazing ray between the Barcelona seafront and the summit is one geometric object, and you can read it in either direction: from Barcelona it says "you must stand 92 m up to see the island", and from Puig Major it says "everything in Barcelona below 92 m does not exist." That second reading erases almost the whole city. The beaches, the port, the Eixample, nearly everything human in Barcelona lives within a few dozen metres of the sea, so from Mallorca the city vanishes and only its thin crown of hills survives: the top 420 m of Tibidabo and the Collserola ridge, the upper 80 m of Montjuïc. Barcelona, in exchange for the 700 m band of Tramuntana it receives, can offer the island only that.

The engine's verdicts, read from the summit of Puig Major:

• Tibidabo's summit is visible, clearing by about 4 m. Two people, one on each summit, 188 km apart, can in principle see each other's mountaintop. (Given the records we've analysed, a 188 km photograph over the Mediterranean would be a respectable entry in any long-sightline collection.)
• The beach at Barceloneta is hidden, 91 m below the grazing ray, the same threshold as the forward direction, read backwards.
• A 25 m rooftop in Barceloneta would need k ≈ 0.29 to appear: on the right winter morning, the upper floors of the seafront skyline flicker into existence for an observer on Puig Major.

So the island sees Barcelona the same way Barcelona sees the island, as a thin strip of high ground floating over the curve. Barcelona just has far less of it to show.

Photo: NASA, ISS061-E-13409, public domain, via Wikimedia Commons.

When to actually look

Geometry sets the stage permanently; aerosols decide the performance. Over 190 km of Mediterranean air, ordinary summer haze extinguishes the contrast long before the geometry fails, which is why both of the era-defining photographs of this sightline, Bret's in 2014 and Puertas's in 2023, were taken in mid-November. Cold, dry air behind a front, a low dawn sun backlighting the ridge silhouette, and a warm sea feeding a touch of extra refraction near the surface: that is the recipe, and it comes together a handful of mornings each autumn and winter. Bret's post notes the Tramuntana shows itself from Barcelona "several times throughout each year," which matches both the physics and the photographic record.

From the geometry side, the checklist is short: get above 92 m, face bearing 157° to 172°, and prefer mornings. Every metre above the threshold adds margin against the day's air. At Tibidabo's height the skyline spans fifteen degrees of horizon under standard conditions, from the Ternelles and Tomir ridges at the range's north-eastern end to Galatzó at its south-western tip, and the 15.5° figure long quoted from panorama simulators matches that computed span almost exactly. On the best refractive mornings the ends stretch toward Formentor at 152° and Sa Dragonera at 175°: twenty-three degrees of Mallorca on the Barcelona horizon.

How the numbers were made

Every verdict above is a terrain profile walked sample by sample. From the observer, the engine traces the great-circle path toward the target across the Copernicus GLO-30 elevation model, tracking the steepest upward angle the terrain has claimed so far; the target is visible if its summit stands above that running angle at its own distance. Earth's curvature drops distant terrain by d²/2R in the observer's apparent frame, and refraction stretches the effective Earth radius by 1/(1−k), which is why a single coefficient cleanly captures "how bent is the air today." For each blocked sightline we re-ran the profile across a range of k values to find the exact flip point, and for the threshold question we bisected the observer's height until the verdict changed. Elevations come from a surface model with real summit values (its Puig Major cell reads 1,430 m against the surveyed 1,436 m, ordinary for a 30 m grid on a sharp peak), and every input is public, so the whole study is reproducible.

Check your own horizon

Every disputed "you can see it from here" claim is now a computation instead of an argument, and this one took an evening. If your coastline has its own version, an island that appears on certain mornings, a mountain someone's uncle swears he saw once, it is checkable:

• Run a 360° viewshed from your spot and see everything the terrain lets you see, in every direction.
• Use point-to-point mode to test a specific claim, with curvature, refraction and the exact blocking terrain named.
• Or browse 162 famous viewpoints we've already computed, Tibidabo, Montjuïc and the Bunkers del Carmel among them.

Test a sightline you've argued about — free

Frequently asked questions

Can you really see Mallorca from Barcelona?

Yes. Under standard atmospheric refraction, three summits of the Serra de Tramuntana stand above the sea horizon as seen from Tibidabo's 512 m summit: Puig de Massanella (clears by 71 m at 190 km), Puig Major (15 m at 188 km) and Puig de Galatzó (13 m at 201 km). No unusual weather is required. What limits sightings in practice is haze, which is why the documented photographs cluster on cold, clear autumn and winter mornings.

How high do you have to be in Barcelona to see Mallorca?

About 92 m above the sea, under standard refraction, for Puig Major to clear the horizon; the engine flips between 91 and 93 m at the seafront. The lowest documented sighting, from 95 m on Montjuïc, sits three metres above that computed threshold. From 52 m the island appears only with strong refraction (k ≈ 0.21), and from the beach itself it would take k ≈ 0.74, which is mirage territory.

Why does Mallorca look like separate floating fragments instead of an island?

Because Earth's curvature hides the island's lower 700 m or so from Tibidabo's height, and even more from lower viewpoints. What protrudes is a fifteen-degree serrated band: the wall around Puig Major and Massanella, the ridge of the Teix, and Galatzó's tip, separated by open sea where the terrain between them stays below the curve. The coastal cliffs sit right on the line, and the towns, the beaches and Palma itself stay under the horizon at every hour of every day.

Was the 2023 photo of Mallorca from the Fabra Observatory real?

Yes, and it contains two different phenomena. The mountain silhouette was ordinary geometry: from Fabra's 415 m, Puig Major clears the horizon by 47 m under standard refraction. The lights of Port de Sóller, at sea level, were the genuinely rare part: reaching Fabra requires k ≈ 0.8, a strong surface duct several times the normal atmospheric bend. The summits did not defy science, and the harbour lights defied only the weather.

Can you see Barcelona from Mallorca?

Yes, the same sightlines work in reverse, because light paths are reversible: from the summit of Puig Major, Tibidabo's summit clears by about 4 m, so the two high points are mutually visible in principle. But the summit sees very little of the city: the same ray that demands 92 m of height in Barcelona also hides everything in Barcelona below 92 m from the summit, and almost all of the city lies lower than that. Only the hilltops survive; seafront buildings would need k ≈ 0.29, a strong but occasionally real winter condition.

How was this computed?

By tracing point-to-point terrain profiles over the 30 m Copernicus GLO-30 elevation model with Earth's curvature and atmospheric refraction in the geometry: six Barcelona observers, six Mallorcan targets, a refraction-coefficient sweep on every blocked line to find its exact flip point, and a height bisection at the seafront to find the 92 m threshold. UpToWhere runs the same computation for any pair of points on Earth.