The zodiacal light
In the heart of the Atacama Desert, one of the best places to observe the sky, an extraordinary celestial spectacle unfolds every night: the zodiacal light. This mysterious column of light, stretching towards the sky from the horizon, appears majestic and captivating, shrouded in an aura of legend. It is a rare phenomenon, scarcely visible because the light pollution from cities hides the most delicate wonders of the firmament.
Cassini’s Discovery: A Headless Comet
Scientific interest in the zodiacal light dates back to the 17th century, when astronomer Giovanni Domenico Cassini attempted to understand its nature. In his book Spina Celeste Meteora, Cassini depicted the phenomenon in four illustrations, describing it as a comet’s tail whose head was invisible, hidden below the horizon. His explanation, although intriguing, was still far from reality.
The modern explanation: cosmic dust and sunlight
Today we know that the zodiacal light is the result of sunlight reflecting off tiny dust particles scattered along the plane of the Solar System. These extremely rarefied particles create a faint glow that stretches like a luminous bridge in the night sky, following the trajectory of the ecliptic, the apparent path of the Sun and planets.
Interplanetary dust
But where does this dust come from? It’s a question that scientists are still trying to answer. For a long time, it was believed that comets and asteroids were the main culprits. Comets release dust as they travel toward the Sun and their ice sublimates, while asteroids, after collisions, scatter fragments along their orbits.
However, recent studies suggest there might be an unexpected contribution from Mars. The red planet, known for its dust storms, could be spreading fine grains into interplanetary space, adding a Martian component to the dust of the inner Solar System.
A phenomenon to observe under dark skies
The zodiacal light is a unique phenomenon, evidence of the dynamic nature of our Solar System. To observe it, however, dark skies free from light pollution are essential. The Atacama Desert, with its clear skies, offers an unparalleled view of this cosmic glow.
