The star that had disappeared from the sky, by Fatoumata Kébé – Libération

The astrophysicist remembers the images and stories at the origin of her vocation. The temporary appearance of a star in the middle of the Middle Ages, identified only in the 2000s, teaches us a dizzying principle: the stars we see are perhaps already dead.

A few images of space were enough to inspire me with a dream of stars when I was a little girl. This dream consisted of having a job linked to the celestial stars. It materialized in the profession I practice today: astrophysicist.

These first images which led me to where I am today, I discovered in an encyclopedia given to me by my parents. There was the Milky Way and some planets. Each in their own way, they opened a window to infinity. What I didn’t yet know when looking at them was that some of them came from a distant past. Fortunately, it was a Channel 5 documentary that taught me why one of astronomy’s nicknames is “the science of the past.” And then during my studies, a story struck me. I will tell it to you in turn. Let’s look to the past.

The year is 1054, at the time of the Song dynasty which ruled part of China from 960 to 1279. Chinese astronomers witnessed the appearance of a new star in the night sky, which still shone in the daytime sky. In the register of one of these astronomers, the presence of this star was indicated as follows: “Zhihe era of the reign, first year, fifth lunar month, jichou day. A guest star appeared southeast of Tianguan, perhaps several inches away. After more than a year, it dispersed and disappeared.”

“Guest star”

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