Why do eclipses occur? Why don’t we have one every month? Why does the Sun sometimes disappear completely, while at other times it turns into a spectacular ring? And why can a total eclipse only be observed from certain areas of the Earth?
To mark the extraordinary Trio of Eclipses that will be visible from Spain between 2026 and 2028, we have developed a new educational resource to help people understand these phenomena in a much more visual way: our new Sun-Earth-Moon tellurium.
The model has been designed and optimised by SpaceRobotics and manufactured at our own facilities using our CNC machines, combining astronomy, design, engineering and digital fabrication in a tool specifically created for our new educational eclipse workshops.
A workshop about the Sun, the Earth and the Moon
To understand an eclipse, we first need to get to know its three main protagonists: the Sun, the Earth and the Moon.
The Sun is our star and the source of virtually all the energy that makes life on our planet possible. It is around 4.5 billion years old, and in its core, where temperatures reach approximately 15 million degrees Celsius, nuclear fusion transforms hydrogen into helium, releasing enormous amounts of energy.
The Earth travels around the Sun while, at the same time, the Moon orbits our planet. This fascinating orbital dance occasionally causes all three bodies to align.
When the Moon moves between the Sun and the Earth, it casts its shadow over a specific region of our planet, producing a solar eclipse.
When the Earth is positioned between the Sun and the Moon, our planet casts its shadow on the Moon, producing a lunar eclipse.
With our tellurium, we can recreate these positions and transform something that is normally explained through diagrams into a phenomenon that participants can see and experience physically.
Why don’t we have an eclipse every month?
This is one of the most interesting questions explored during the workshop.
Since the Moon orbits the Earth approximately once a month, it might seem logical to think that we should have a solar eclipse at every New Moon and a lunar eclipse at every Full Moon.
But this is not the case.
The Moon’s orbit is tilted by approximately 5 degrees relative to the plane of the Earth’s orbit around the Sun. As a result, during most months the Moon passes slightly above or below the alignment required for an eclipse.
For an eclipse to occur, in addition to being in the correct phase, the Moon must be close to one of the points where its orbit crosses this plane, known as nodes.
This is where the tellurium becomes a particularly useful educational tool: it helps participants visualise that simply placing the Sun, Earth and Moon roughly in a straight line is not enough; the geometry of their orbits is essential.
Total, partial or annular: not all eclipses are the same
During the workshops, we also discover that there are different types of solar eclipses.
During a total eclipse, the Moon completely covers the solar disc. For a few moments, the sky darkens and the spectacular solar corona, the outermost part of the Sun’s atmosphere, can become visible.
During a partial eclipse, the Moon covers only part of the solar disc.
There is also a third possibility: an annular eclipse. The Moon’s orbit is not perfectly circular, so its distance from the Earth varies. When the Moon is farther away, its apparent size in our sky is slightly smaller. If the correct alignment occurs at that moment, the Moon is unable to completely cover the Sun, leaving a spectacular bright ring of light visible around it.
Our tellurium also allows us to introduce concepts such as the umbra and penumbra. The small region reached by the Moon’s central shadow can experience totality, while a much larger area lies within the penumbra and experiences the eclipse as a partial one.
This makes it much easier to understand why two people in different locations can experience the very same eclipse in completely different ways.
Spain, the Stage for Three Extraordinary Eclipses
Spain is experiencing an exceptional astronomical period.
Between 2026 and 2028, three major consecutive solar eclipses will be visible from the Iberian Peninsula:
12 August 2026 — Total Solar Eclipse
2 August 2027 — Total Solar Eclipse
26 January 2028 — Annular Solar Eclipse
Three eclipses in three years make this an extraordinary opportunity to bring astronomy closer to children, families and educational centres.
That is why we want to take advantage of these remarkable events not only to observe them, but also to understand what is actually happening above our heads.
Building to Learn
The tellurium itself is an important part of this philosophy.
Its design has been developed and optimised by SpaceRobotics, with the different wooden components then manufactured using our own CNC machines.
Gears, supports, orbital elements and other components come together to form a small mechanical system that allows us to represent the relative movements of the Sun-Earth-Moon system.
Behind this seemingly simple object are numerous disciplines: astronomy, physics, mathematics, engineering, design and digital fabrication.
This is precisely the kind of learning we aim to promote through our STEAM workshops: science should not simply be something we listen to or memorise, but something we can build, move, observe and experience.
New Eclipse Workshops at the Museo Lunar
These Sun, Earth and Moon workshops are part of the new activities we are developing at the Museo Lunar – Space and Science Centre.
During weekends, the workshops are offered as part of our Family Science activities, allowing children and adults to discover together how our Solar System works and prepare for the upcoming eclipses.
During weekdays, the activity is designed for schools, forming part of our educational workshop programme and adapted to the different ages of the students.
The aim is to turn eclipses into an opportunity to learn much more than the phenomenon itself: to discover our star, understand the movements of the Earth and the Moon, experiment with light and shadows, and explore how astronomy allows us to predict with remarkable precision events that will take place months, years and even centuries into the future.
Looking at the Sun Also Means Learning How to Do It Safely
An essential part of the workshop is learning how to observe the Sun safely.
An eclipse does not make the Sun’s radiation any less dangerous. As long as any bright part of the solar disc remains visible, we must never look directly at it without protection specifically designed for solar observation. Appropriate eclipse glasses must use certified solar filters compliant with the ISO 12312-2 standard.
Conventional sunglasses, no matter how dark they are, are not suitable for looking directly at the Sun. Improvised methods such as photographic negatives, CDs or smoked glass are also unsafe. Telescopes, cameras and binoculars require specific solar filters placed in front of their optics.
We also teach simple indirect observation methods, such as pinhole projection, which allow participants to observe the shape of the solar disc without looking directly at our star.
Eclipse Glasses to Keep Learning After the Workshop
We want the experience to continue even after the activity has finished.
That is why all participants receive their own solar eclipse glasses, which they can keep and use to prepare for the upcoming eclipses. Each pair includes a QR code linking to an explanation by Astronauta LiLi about the Sun and how to observe it safely.
Astronauta LiLi – Solar Observation Guide
The idea is simple: first, we learn what the Sun is. Then we discover how the Earth and Moon move. We build and use our tellurium. We recreate an eclipse. We understand why it happens and learn how to observe it safely.
Finally, we can go outside, look up at the sky and be ready to see everything we have learned actually happening above us.
Because few experiences can inspire as much curiosity about science as building something with our own hands, understanding how it works, and then discovering that the very same phenomenon is taking place hundreds of thousands of kilometres above us.
A First Version Tested at the European Space Agency
Before developing this new version of the tellurium, an initial, lighter and simplified version of the Sun-Earth-Moon workshop was tested at the European Space Agency (ESA).
This experience provided a practical opportunity to see how a physical model can help participants understand concepts that can be difficult to visualise through images or explanations alone, particularly the relative movements of the Sun, Earth and Moon and how eclipses occur.
Building on this experience, we continued to develop and improve the activity, leading to the creation of our new tellurium. Its design and manufacturing process have been further optimised, making it one of the main educational tools used in our eclipse workshops.
