There are children who grow up with grandiose dreams, imagining themselves as astronauts, scientists, or explorers of distant worlds. Eleonora Sani She was one of them, even if she didn't dream of becoming an astrophysicist or an astronomer, but she was driven by an irrepressible curiosity about how things worked. From a young age, she was fascinated by nature: she wanted to understand why ants moved in lines or why droplets escaped from a broken leaf. At the same time, she was intrigued by mechanics: she would disassemble and observe motorcycle engines with her grandfather to understand how they worked.
This curiosity guided her academic choices. She was also fascinated by biotechnology and engineering, but ultimately chose physics for its universal language: mathematics.“Mathematics transcends cultural barriers, it is a universal language that describes nature and the cosmos.“.
Eleonora wanted to understand why the ants were all moving together, how things around her worked, but it was towards the infinity above her head that her gaze most often wandered. That night sky, dotted with distant lights, spoke to her of mysteries yet to be solved. And so, from Siena a Florence, until Chile, Eleonora followed the passion that had always flowed within her, becoming an established astrophysicist. In this interview she tells us about her extraordinary journey, made of study, research and desire to understand the cosmos.
Why did you choose astrophysics?
Astrophysics allows us to explore a wide range of areas of physicsQuantum mechanics, electromagnetism, general and special relativity, celestial mechanics. I liked the idea of integrating different fields of knowledge to interpret what we observe. Furthermore, the sky has always fascinated me, and stargazing was a pastime that fueled my imagination.
Tell us about your educational and professional background. How did your career in astrophysics begin?
I was born in Siena, but my academic training took place in Florence, where I earned my PhD in astrophysics. During my PhD and in the first years of my career, I lived between Florence and Munich, working at the’National Institute of Astrophysics (INAF) and the Max Planck Institute. This six-year period was crucial in building my career, alternating research and technical insights, especially in the field of optical-infrared and submillimeter astronomy.
How would you describe your work to someone unfamiliar with the world of astrophysics?
If I had to make a comparison, I would say that my role is similar to that of a Formula One driver. The pilot is the expert who tells the technicians what's needed to win the race: what setup, what type of tires, what engine. I do the same with telescopes and instrumentation. I translate what the scientific community needs into technical specifications: We need this instrument improved in this way to achieve certain scientific results. This allows me to optimize the technology available and ensure that the tools provide the community with the maximum of their capabilities.
In addition to this technical role, do you also deal with research?
Yes, the other fundamental part of my work is scientific research, which I conduct independently. The institute I work for gives me the freedom to manage my own investigations, and my field of study is the relationship between supermassive black holes and the galaxies that host them. Over the past twenty years, it's become clear that there's a strong connection between the two: black holes influence the development of galaxies, and vice versa.
What specific area does your research focus on?
My research focuses on connection between supermassive black holes and the galaxies that host them. In addition to the theoretical part, I began working on the more technical aspects of astronomical instrumentation. These skills led me to collaborate with the Large Binocular Telescope in Arizona, where I spent many nights observing the sky and optimizing the instruments needed to meet the needs of the scientific community.
After this experience, what brought you to South America?
Ten years ago the opportunity arose to work for the’European Southern Observatory (ESO), a prestigious European observatory based in Chile, both in Santiago that in the desert of Atacama. Together with my husband Claudio, we weighed the pros and cons of moving so far from Italy. Despite the difficulties of leaving our roots, we decided to seize the opportunity, initially for a period of 3-5 years. Now, after ten years, we've settled here and plan to continue for a while longer.’
What was your first experience when looking at the stars through a telescope?
Gazing at the Chilean sky, one of the clearest in the world, is an indescribable experience. The first time I observed the stars through a telescope, it was like entering another world: the feeling of vastness and connection with the universe is overwhelming. It's a moment that changes you, making you feel small but also part of something immensely large. Studying the universe is like lifting the veil on infinity. Every discovery not only surprises you, but opens up new questions, new challenges.
How would you explain the immensity of a galaxy to someone unfamiliar with the cosmos?
To understand how big a galaxy is, I would avoid speaking in kilometers or meters: the numbers would be so enormous that they would lose meaning. In astronomy, we use the speed of light as a reference. For example, a galaxy can be hundreds of thousands of light-years across, which means that even traveling at the speed of light, which is the fastest possible, it would take hundreds of thousands of years to cross it.
The speed of light is a universal constant, it varies neither in space nor in time, and it is incredibly fast: about 300,000 kilometers per second. This makes it clear how immense cosmic distances are.
What is the role of supermassive black holes in the centers of galaxies?
They play a key role. A galaxy is made up of stars, gas, dust, and complex dynamics that influence it, both internally and from the surrounding environment. When the gas within the galaxy reaches the central region, it is swallowed by the black hole, a process known as growth. This causes the black hole to grow in mass.
When the growth is significant, that is, when the amount of gas absorbed is high, the black hole "activates"“ and converts matter into energy. This energy is released in the form of light and heat, with extraordinary efficiency: a black hole is 100.000 times more efficient at converting matter into energy than a star. Although this phase of activity lasts a relatively short time compared to the life of a galaxy, it is one of the more powerful energy events of the universe and is thought to regulate the rate of star formation in the host galaxy.
What's the next big step for astrophysics?
The next big step is undoubtedly the search for extraterrestrial life. The dream would be to identify intelligent life, but before we get there, we need to work on intermediate steps. We need to find planets with favorable conditions for the development of life and identify tracers of these conditions, such as water vapor, in the atmospheres of exoplanets. Another goal is to observe the first stars formed in the universe, which are currently only theorized: these are stars composed exclusively of hydrogen and helium, with no other chemical elements. For now, we don't have telescopes sensitive enough to detect them, but we're getting closer. Their identification would confirm models of the universe's formation and evolution.
Has artificial intelligence transformed the way we analyze astronomical data?
Not completely, but there is great interest in its use. Artificial intelligence can be a valuable tool, like a advanced calculator. It is particularly useful in analyzing huge and complex databases, allowing patterns and correlations to be identified much more quickly. However, it remains a tool: the interpretative and physical part remains a human task.
Have you already had the privilege of participating in an important discovery?
Yes, I have been fortunate enough to be involved in observing a neutron star merger in 2017. It was an exceptional discovery, as it confirmed that heavy chemical elements, such as gold and platinum, are formed in these events. This result, which required the international collaboration of many research groups, closed an important circle in our cosmological model.
How long would it take to travel across a galaxy, and how much does this help us understand its vastness?
To give a concrete idea of the size of a galaxy, we can think about the transit times. To travel across the entire galaxy would take about 100,000 years at the speed of light. This means that a human being would have to live 100,000 years to travel across it. By comparison, sunlight takes only 8 minutes to reach Earth.
Another useful analogy is to imagine the galaxy as a huge city, while our Solar System would be a small neighborhood. The size of the Solar System, considering all its peripheral elements, is about a light-year, while the galaxy extends for 100,000 light-years. Our “galactic ”city” It is therefore 100,000 times larger than the environment in which the Earth is located.
What is your dream as an astrophysicist?
On the one hand, I would like to identify the progenitors of the first stars of the universe. On the other hand, I'm fascinated by the mystery of supermassive black holes. I'd like to discover why and how their energy influences the evolution of the galaxies that host them. It's a well-documented phenomenon, but the theoretical explanation remains incomplete. Finding the key would be extraordinary.
Did you find inspiration in Chilean culture, perhaps in indigenous legends related to the stars?
Yes, absolutely. I've always loved outreach and I've been interested in astronomical myths in different cultures. Each population interprets the stars according to its own mythology and tradition. In Chile, I discovered the rich mythology of the Mapuche, one of the most significant indigenous communities.
For them, mother earth, called Ñuke Mapu, is the center of the universe and many constellations reflect this connection with nature. For example, the Southern Cross, an iconic symbol of the Southern Hemisphere, is known as Chacana in their language. It's fascinating to see how stars always play a central role in the stories of every culture.
What would you say to a young person who dreams of becoming an astrophysicist?
I would say to follow your curiosity and passion for science, without giving up in the face of difficulties. Astrophysics is a complex field, but the challenges are what make it fascinating. Research can take tortuous paths and requires perseverance. Every open question is an invitation to explore, and every discovery is a step toward understanding our place in the universe.
