08/04/2021

World Astronomy Day is celebrated this Thursday (8)

Cecilia Manzoni

Bills to pay, career changes, relationship problems, plans that go wrong. Many of the issues that plague human beings daily seem irrelevant in the face of the great mysteries that the universe holds. Where did we come from and where are we going? We still don't have the answer.

This is a fundamental question in astronomy, the science that studies the formation and evolution of celestial bodies. If we are all made of stardust, as Carl Sagan proclaimed, it is understandable that new discoveries in this field of knowledge are so fascinating. To celebrate its importance, World Astronomy Day is celebrated this Thursday (8).

Karín Menéndez-Delmestre, a Puerto Rican astrophysicist at the Valongo Observatory of the Federal University of Rio de Janeiro (UFRJ), believes that one of the main attractions of astronomy lies in a simple gesture: looking at the sky. “Just go to a place further away from large urban centers, on a dark night, and you can see stars and a series of structures that are very distant and unknown. The sky is beautiful, and it's for everyone,” she says.

The unpretentious observation of space evokes an immediate feeling of connection to the origins of humankind, the researcher points out. “All of this makes us think about the origin of the Earth, and feel that we are part of a whole, a tiny blue dot in this sea of stars. It creates a desire to understand how all this happened, how the 'Big Bang' occurred , and what our future will be like. This captivates people's imagination in a very natural way,” she believes.

History and development

It is no coincidence that the origins of astronomy date back to this spontaneous act of looking at the sky. Prehistoric cultures linked the observation of celestial bodies to the prediction of events, such as the seasons, rainy seasons, and river floods. Only from the 17th century onwards, with the development of instruments such as the telescope, did astronomy begin to incorporate the scientific method.

Created by the German-Dutchman Hans Lippershey (1570-1619), the telescope, also called a spyglass, allowed the birth of modern astronomy, says Karín. “A landmark event was when Galileo Galilei first pointed a telescope at the sky and detected, among other things, Jupiter's system of moons. This generated a major paradigm shift, because they discovered that Earth was not the center of everything,” she recounts.

The first maps of the Milky Way and catalogs of nebulae emerged in the 18th and 19th centuries. But it was only in 1920, motivated by the debate between astronomers Harlow Shapley (1885-1972) and Heber Curtis (1872-1942), that humanity discovered the existence of other galaxies, giving rise to extragalactic astronomy.

The advancement of technologies, such as the advent of photographic plates and space satellites, has facilitated the storage of data on celestial movements, which, for centuries, were recorded only in notes and drawings. “Photographic plates take advantage of the crystallization of certain chemical elements to create large photographs, which are recorded on glass. Space satellites allow us to conduct studies at high energies such as gamma rays and X-rays,” reports the researcher from the Valongo Observatory.

She further adds that, because they are above the atmosphere, the special satellites have facilitated the generation of clearer images of space. "The Hubble Space Telescope was a major revolution in our ability to see details of very distant objects, galaxies that had formed when the universe was very young, only a few hundred million or billion years old."

Currently, astronomy is divided into three branches: observational astronomy, theoretical astronomy, and instrumental astronomy. The first consists of obtaining data from observation, using the basic principles of physics. The second is oriented towards the development of analytical models and computer simulations that describe astronomical objects and phenomena. Instrumental astronomy deals with the development of new instruments for the advancement of this science.

Relationship with mathematics

With its laws and equations, mathematics was and continues to be a fundamental element in the study of the movement of celestial bodies. And the reverse is also true. The director-general of IMPA, Marcelo Viana, says that mathematics, to a large extent, was born from astronomy. "It is no coincidence that, until the 19th century, practically every mathematician was an astronomer," he recalls.

“Celestial bodies are very far away, inaccessible to everything except sight. The only way to understand their behavior is to observe them and, from that, intuit mathematical laws that they seem to follow. Such laws can be challenged by new observations. If they pass the test, they become useful for predicting the future, which is one of the great goals of science. In this way, astronomy provides problems for mathematics, which pays back with solutions,” explains Viana.

Enchanted by astronomy during his childhood and adolescence, the director-general of IMPA reveals that he even had a small notebook where he wrote down all the information related to the science that he found. “I devoured all the information that came my way. I wrote down in pencil the data relating to the sun, planets, comets and stars that I found in this bibliography. I learned the names of 'astronomical' numbers like trillions, quadrillions, quintillions, so I could read the numbers that appeared in astronomy.”

His youthful desire to become an astronomer resurfaced when he learned in 1975 that NASA would be sending two probes to Mars. Viana ultimately stayed in mathematics, but astronomy remains present in his work through dynamical systems, his specialty.

Henri Poincaré's (1854-1912) work, "Methods of Celestial Mechanics," emerged to overcome difficulties with Newton's equation of gravitation, which governed the movement of planets around the Sun. "The new methods presented in the book ended up giving rise to the field of dynamical systems, which consolidated itself throughout the 20th century," says the director-general of IMPA.

Contributions to society

Some of the technologies developed by astronomy are found, in much less complex versions, in devices and tools we use in our daily lives. Karín Menéndez-Delmestre cites as an example the charge-coupled device (CCD), a sensor used in telescopes, which is present in the chips of digital cameras and smartphones. "It is a technology initially developed to achieve specific scientific objectives in astronomy, such as the possibility of seeing increasingly distant galaxies, and which ended up being incorporated into people's daily lives."

Focused on one of the universe's greatest mysteries, the Puerto Rican researcher aims to map the effects of dark matter's gravitational pull on the Milky Way and identify how this will modify our galaxy in the future. “What inspires me to do astronomy is not so much the immediate applicability, but the desire to contribute to humanity's knowledge. I want to understand more about the universe and how it became what it is now. How did gas begin to turn into stars, then galaxies, and how did planets and black holes begin to emerge? Only basic science can help us find these answers.”