The exhibition Extraterrestrials. Is There Life Outside Earth? at the CosmoCaixa Science Museum immerses visitors in the subject through five thematic areas and a poignant epilogue.
These areas are preceded by an inspiring photo opportunity featuring a hypothetical exploration of the subsurface ocean of Europa, one of Jupiter’s moons, which is covered by an ice crust between 10 and 40 km thick. Beneath this crust, where the ocean meets Europa’s solid substrate, organic chemistry may have developed to a level complex enough to give rise to microscopic life forms. This ocean remains in a liquid state due to tidal forces exerted by Jupiter. The exhibition’s scenography presents imaginary bioluminescent organisms – resembling real marine molluscs popularly known as sea angels – being observed by a robotic submarine.
After encountering these hypothetical aliens, visitors enter the five areas of the exhibition, each introduced by a comic strip by the illustrator Juan de Dios Tenorio.
In this first area, visitors will gain an understanding of the cosmos we are part of. A striking introductory audiovisual provides insight into the structure of the universe and our place within it, taking visitors on a journey from the deepest reaches of space to Earth. A touch table allows visitors to explore key facts about our galaxy, the Milky Way.
Placing Earth in its context, thanks also to materials such as the cosmic calendar devised by Carl Sagan, helps us grasp our insignificance. This calendar scales the 13.8-billion-year history of the universe down to a traditional 12-month calendar: the Big Bang would occur in the first instant of 1 January; Earth would have formed on 1 September; and Homo sapiens would have appeared just six minutes before midnight on 31 December. We find ourselves in the final fraction of the last second of the last day of that year. As Sagan put it, “Our existence is but a blink in cosmic time.”
The exhibition also addresses the physical characteristics of Earth and why it is and is not special at the same time. We live on a relatively ordinary planet, orbiting an ordinary star in an ordinary galaxy, meaning that planets similar to ours must be abundant. Earth is distinguished by its vast biodiversity, teeming with microscopic organisms, animals and plants, as demonstrated in a large-format audiovisual display.
Water and carbon are the “building blocks” of life on Earth. These elements and molecules are found in abundance in the universe. It is no coincidence that the mantra follow the water is applied when searching for life outside the Earth. This section features an interactive module on the circumstellar habitable zone – the region around a star in which the temperature of a planet allows for the presence of liquid water on its surface. In this module, visitors can move a planet’s globe to bring it closer to or farther from the Sun and observe on a screen how its climate would change. When the distance from the Sun is just right, the plane’s climate resembles the Earth’s, with liquid water on the surface, provided it has an atmosphere and a mass similar to that of our own planet.
For millennia, humanity has debated the existence or not of life on other worlds. This second area presents the historical discussion between these two opposing viewpoints, a debate that traces its roots back to Classical Greece. The exhibition explores the diversity of perspectives on the possible existence of extraterrestrial life from different points of view, including science, philosophy, religion and art.
Historically, the dominant viewpoint has been the uniqueness of Earth, which, before the Copernican Revolution, was believed to be at the centre of the universe. However, an avalanche of astronomical discoveries since the 17th century has fuelled the possibility that we are just one among many in a cosmos where each star could be a sun surrounded by potentially habitable worlds.
Countless stories since then have fantasised about this possibility, echoing the scientific debates of their time. The exhibition revisits historical works that explored the idea of extraterrestrial life, such as the books Entretiens sur la pluralité des mondes (1686), La pluralité des mondes habités (1865) and Mars and Its Canals (1906), as well as Georges Méliès’ film Le Voyage dans la Lune (1902).
Over time, stories about space travel and extraterrestrial beings evolved into works that imagined humanity “from the outside”, using this perspective to critique contemporary society.
In this area, visitors will be immersed in the perspectives from which art, literature, film and television have depicted extraterrestrial life, highlighting the fact that the greatest inspiration for these imaginings comes from terrestrial life itself.
Films like E.T. the Extraterrestrial, Predator, and Star Trek, with its iconic Mr Spock, have taken an anthropocentric approach, portraying extraterrestrials with human-like appearances. But there have also been zoomorphic interpretations, where alien life has been depicted as resembling animals, such as the heptapods, cephalopod-like aliens in The Arrival. In other cases, they have taken on entirely different forms, as seen in literary works like Solaris, The Black Cloud, or Expedition, where creators have unleashed their imagination. An audiovisual display contrasts the appearance of these fictional characters with the historical context of their films, revealing that, ultimately, these creations are a reflection of our fears or our desires.
This section also reveals that some life forms on Earth are so strange they seem to have come from other worlds. Life can thrive in extreme and hostile environments, including places with temperatures exceeding 100 degrees, in deserts with intense solar radiation, in lakes beneath the Antarctic ice and even inside the reactors of nuclear power plants. The discovery of life in such conditions has raised expectations of finding it on worlds vastly different from our own.
Through an interactive game, visitors can discover Earthly creatures with alien-like appearances, such as nudibranchs, deep-sea fish and certain insect species. Additionally, using microscopes, they will be able to take a close look at other fascinating yet real organisms, such as Artemia salina – a tiny crustacean commonly known as the Sea Monkey.
The penultimate area exposes the current state of one of humanity’s most important missions: from the search for life within our own solar system using robotic explorers to the discovery of more distant worlds, the exoplanets and the hope of detecting an Earth 2.0 in the not-so-distant future. Science considers it probable that life could exist on other worlds, although any life we detect in the near future is most likely to be microscopic.
The search for life in our solar system takes us to places like the icy moons of the giant gas planets, such as Europa, Enceladus and Titan. At this point in the exhibition, an interactive multimedia display and a holographic fan allow visitors to discover the worlds in our solar system that have subsurface oceans of liquid water.
Mars also plays a key role in the search for life and, as a result, the exhibition features the real Ksar Ghilane 002 meteorite, a Martian shergottite. It is known that in ancient times, liquid water once flowed on the surface of Mars, possibly allowing life to emerge. NASA is searching for evidence of this with tools such as the Ingenuity helicopter and the Perseverance rover. The latter is designed to look for signs of life in Martian soil, collect data on the planet’s geological past and even record sounds from the surface of the Red Planet. The exhibition showcases impressive full-scale 1:1 models of both these devices.
This section also explores the possibility of finding life on more distant worlds, on exoplanets. Since the discovery of the first extrasolar planet in 1992, more than 7,000 exoplanets have been identified, some of which orbit within the habitable zone of their respective stars. Interactive modules allow visitors to learn about the different techniques used to detect exoplanets and the physical principles behind them, helping to assess whether any of these distant worlds could be a potential Earth 2.0.
In this final area, the exhibition focuses on the possibility of extraterrestrial civilisations and the potential ways we might communicate with them.
The SETI (Search for Extraterrestrial Intelligence) project, for example, is dedicated to listening to the cosmos using massive radio telescopes in search of possible signals of artificial origin. So far, the universe remains silent to us, we have heard nothing. More advanced and modern strategies have expanded the search with a less restrictive approach, focusing on identifying signs of technological development rather than direct communication attempts. The presence of highly advanced technology could leave detectable imprints – techno-signatures – in the light emitted by a planet.
There have also been attempts at reverse communication, such as the Voyager golden records, designed to inform any potential extraterrestrial intelligence of life on Earth. The exhibition features replicas of these records, which contain sounds and images showcasing the diversity of life and culture on our planet.
Advances in science and technology allow us to dream of discovering life on other worlds in the near future. The next generations of telescopes and space missions will be able to search for chemical signatures of life in the atmospheres of exoplanets that could potentially support it. For this reason, the exhibition concludes with an immersive sensory experience, where visitors are surrounded by real images of the cosmos captured by various NASA and ESA space missions. This epilogue invites us to reflect on how our lives would change if we were to discover that we are not alone in the universe.
Image reel from the exhibition “Extraterrestrials. There is life beyond Earth.”
Statements by Montserrat Villar, scientific advisor of the exhibition.
Statements by Benjamín Montesinos, scientific advisor of the exhibition.
Representation of the Milky Way.
Metaphorical recreation of what it would be like to travel through the deepest universe.
NASA images to recreate what it would have been like to fly near Jupiter with the Juno spacecraft.
Recreation of the Orion Nebula from images from NASA and ESA telescopes.
Scenes from “The Blob.”
Scenes of inhabitants of the Moon in the film "Journey to the Moon", by Georges Méliès.
Fragment of the silent film “Aelita: Queen of Mars”.
