Astronomy. On Friday March 17, around thirty people attended the conference “Probing the Universe with spectroscopy” at the Valcourt Observatory, proposed by the Astronomical Society of Haute-Marne and given by Pietro Bergamini.
“Spectroscopy is a way to travel far without leaving Earth. Our knowledge of the Universe essentially comes from electromagnetic radiation,” said Pietro Bergamini straight away. Spectroscopy is the breaking down of light into its different wavelengths.
Some sources emit light made up of a small number of very precise colours, quite distinct from each other. Others produce all colors seamlessly. Still others a continuous light, but marked with dark lines.
All of these behaviors provide information regarding the object that emitted the light, and help to understand its physics. “Information that must be decoded”, underlined the speaker. “Light is the part of the radiation that our eyes perceive, but there are others such as infrared and ultraviolet rays or radio waves,” said Pietro Bergamini.
He established a history of the discoveries made in the 17th century with Newton who passed white sunlight through a prism in order to decompose it into light rays of different colors. The study of the spectra of sunlight (the rainbow is a well-known example) therefore began with Newton.
“By observing more finely, we discovered dark lines in these spectra. They constitute the “signature” of the atoms of matter contained in the external layers of the Sun. This is how we were able to learn the composition of the Sun’s atmosphere and also its temperature. This technique has been extended to other celestial bodies, such as stars, nebulae, galaxies etc,” he explained. Enough to learn “a lot regarding the composition and structure of the Universe”. For example the “leakage” of galaxies which might be measured by spectroscopy, indicating that the Universe is expanding. The applications are multiple.
“Other discoveries coming soon”
“Using this technique, the first exoplanet was also detected in 1995. On Mars, satellites and rovers use it to analyze rocks. The evolution of instruments, such as the James Webb Space Telescope, promises other discoveries soon,” concluded Pietro Bergamini.
Due to the rainy weather, it was not possible to observe the sky with the telescope at the end of the conference, but a session at the Paul-Macquart planetarium was organized at the end of the evening for the volunteers.
