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Conspiracy Wiki documents conspiracy theories as cultural and historical subjects — what is claimed, by whom, and what the evidence shows — with cited sources, distinguishing established facts from allegations and disputed claims. Articles are community-maintained for research, education, and discussion, and do not endorse any theory. See our Disclaimer for full terms.

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The Ummo Letters

DiscussionHistory
Contents
  1. Overview
  2. A Landing, Announced in Advance
  3. The Physics in the Envelopes
  4. Issue 29
  5. The Open File

Overview

They came by ordinary post. Typed pages, single-spaced, in careful formal Spanish, each stamped with a mark that looked like a closed parenthesis, a plus sign, and an open parenthesis: )+(. Starting in 1965 and 1966, envelopes like these began landing at the homes of UFO enthusiasts around Madrid, and the authors introduced themselves without much ceremony. They were, they wrote, scientists from Ummo, a planet orbiting the star Iumma, 14.6 light-years from Earth. They had been living here quietly since 1950. They had things to explain.

The first and most devoted reader was Fernando Sesma, who presided over the Society of Friends of Space, a Madrid tertulia of saucer enthusiasts, and whose circle became the letters' first audience. From there the correspondence spread — to hundreds of recipients across Spain and eventually France, arriving steadily until about 1988. By 1983 one count already put the corpus at some 6,700 pages; estimates of the full total vary widely, but everyone agrees it was enormous. The material was dense and strangely consistent: cosmology, biology, the grammar of the Ummite language, the social organization of a distant planet, all of it cross-referenced across years of mail from authors nobody ever met.

A Landing, Announced in Advance

On February 6, 1966, witnesses in the Madrid district of Aluche reported a circular craft descending on three legs. Among those who came forward was a local psychologist named José Luis Jordán Peña, who sketched the object for the press — with the )+( symbol on its underside. The letters and the sightings now had each other.

Then the campaign got bolder. In the spring of 1967, letters told recipients that a ship would soon show itself, and on June 1, 1967, over San José de Valderas on Madrid's edge, one apparently did. Photographs circulated of a pale saucer bearing the symbol. Hollow capsules of fluoride plastic turned up nearby, containing plastic strips marked )+( — material exotic enough, it was said, to be catalogued as something out of NASA. The American photo-analysis group Ground Saucer Watch later examined the Valderas pictures and reported a small object held close to the camera, by its estimate a plate about eight inches across with the symbol painted on in ink, and researchers came to regard the images as shots of a model. The letters kept coming anyway.

The Physics in the Envelopes

What held serious readers was not the saucer. It was the prose. The documents laid out an integrated scientific and philosophical system — physics, information theory, ethics — that stayed internally coherent across decades and thousands of pages, which is a hard trick for any author, terrestrial or otherwise. The French plasma physicist Jean-Pierre Petit became the corpus's most credentialed champion, writing books on Ummite science and maintaining from 1991 onward that the texts showed signs of a superior intelligence; he has credited them with inspiring parts of his own cosmology work. In Spain, the ufologist and journalist Juan José Benítez engaged with the material in his books. Working the other side of the street, investigative journalist Manuel Carballal picked at the affair in the Spanish press, tracing who might have typed what, and for whom.

Issue 29

April 1993. In issue 29 of the Madrid skeptical magazine La Alternativa Racional, Jordán Peña — the same psychologist who had reported the Aluche craft twenty-seven years earlier — told readers that he was the one who wrote the letters from Ummo. He framed it as research. He wanted, he said, to test his thesis that paranoia was more widespread than psychiatrists believed, so he "decided to create a myth called Ummo, providing it with a false landing and falsified traces." He assembled a study group of intelligent people and watched what the letters did to them. "The hoax was almost perfect," he wrote. In later tellings he added stranger flourishes, including a claim that the CIA had supplied him with radioactive sand for the landing sites.

The confession settled less than one might expect. Many recipients rejected it outright, and their argument was practical rather than mystical: one man, thousands of technically dense pages, twenty-five years of sustained coherence, letters posted from cities around the world. Petit and others held that the corpus was simply beyond a single author's reach, whatever Jordán Peña had signed his name to. The psychologist had, after all, spent decades demonstrating a talent for saying things that were not so.

The Open File

The letters outlived their confessed author's confession. Devotional offshoots persisted into the following decades, including a Bolivian group calling itself the Daughters of Ummo, still active some twenty years after 1993. Chile's CEFAA — the government's official aerial-phenomena agency — keeps the case in its historical files under a heading that does its judging for it: the great ufological fraud forged in Spain. The pages themselves are still out there, scanned and traded and argued over, and the affair is routinely described as one of the largest coordinated document campaigns ever aimed at the UFO world. What remains, as at the start, is what arrived in the mail: type, a postmark, and a symbol.

StatusUnresolved / Disputed
Gov. InvolvementAlleged
LocationSpain
Time Period1966-02-06 – 1993-04-30
CountriesSpain, France
ClassificationUnclassified
Media CoverageModerate
Key Players
  • · Madrid psychologist who in 1993 stated he had authored the Ummo letters as an experiment in belief
  • · President of Madrid's Society of Friends of Space and first recipient of the letters
  • · French plasma physicist and the corpus's most prominent scientific proponent
  • · Spanish investigative journalist who probed the affair in the press
Organizations
  • · Fernando Sesma's Madrid tertulia, the letters' first audience
  • · US photo-analysis group that examined the San José de Valderas photographs
  • · Chile's official aerial-phenomena agency, which maintains a historical case file on the affair
EvidenceDocuments, Scientific, Circumstantial
Themes
extraterrestrial contactanonymous letterselaborate hoaxesbelief formationspanish ufology
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Timeline of Events

—
  1. 1965-01-01
    First letters reach Madrid

    Typed documents signed with the )+( symbol, claiming authorship by scientists from the planet Ummo, begin arriving with Fernando Sesma and his Society of Friends of Space tertulia.

  2. 1966-02-06
    The Aluche sighting

    Witnesses in Madrid's Aluche district report a circular craft on three legs; psychologist José Luis Jordán Peña comes forward with a sketch showing the )+( symbol on its underside.

  3. 1967-06-01
    San José de Valderas

    After a letter campaign announcing a landing in advance, a saucer is reportedly seen and photographed over San José de Valderas; fluoride-plastic capsules marked )+( are found nearby. Analysts later report the photos show a small model close to the camera.

  4. 1991-01-01
    Petit publishes on Ummite science

    French plasma physicist Jean-Pierre Petit begins publicly arguing that the Ummo corpus shows signs of a superior intelligence, writing books on its physics.

  5. 1993-04-30
    Jordán Peña's confession

    In issue 29 of La Alternativa Racional, Jordán Peña states he wrote the Ummo letters himself, describing the affair as an experiment in how paranoid belief forms. Many recipients reject the claim, arguing one man could not have produced the corpus.

  6. 2013-01-01
    Offshoots persist

    Devotional groups built on the letters remain active long after the confession, including a Bolivian sect calling itself the Daughters of Ummo, reported active some two decades on.

Categories

  • UFOs & Extraterrestrials
  • Channeling & Contact

Sources & References

  1. governmentUmmo: The Great Ufological Fraud Forged in Spain (historic case file)
    (2026)CEFAA (Gobierno de Chile)
  2. articleJosé Luis Jordán Peña's 1993 confession, La Alternativa Racional No. 29
    (1993)La Alternativa Racional (reproduced by ufologie.patrickgross.org)
  3. bookUmmo Hoax — Encyclopedia of Occultism and Parapsychology
    (2001)Gale, via Encyclopedia.com
  4. articleUmmo
    (2026)Wikipedia
  5. articleThe Ummo Case: The UFO Hoax That Fascinated Spain
    (2026)Foro3D
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Last updated July 16, 2026. Community-maintained and reviewed under our Editorial Standards.

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Last edited by Oracle on 7/16/2026