The Endangered Night: A Dive into Darkness and Its Vital Role
France 5’s documentary, "Voyage au cœur de la nuit" ("Journey to the Heart of the Night"), presented by "Science grand format," explores a pressing question: Is the night, as we know it, in danger? This isn’t a lament for the dwindling nightlife scene, but a profound inquiry into the state of the natural darkness that envelops our planet each evening. The film, directed by Véronique Préault, argues that escalating artificial light pollution is disrupting ecosystems and causing us to forget the existence of true, profound darkness.
The documentary immediately establishes the fundamental importance of night. One of the many scientists interviewed states, "For us, it’s time to go to sleep, but for many creatures, it’s time to wake up." The film portrays the night as a conductor, orchestrating the lives and behaviors of a vast array of living organisms. Préault’s aim is to "turn off the light," metaphorically and literally, to reveal the hidden world that thrives under the cloak of darkness and the devastating impact of its diminishing presence.
The film begins with the sunset, a seemingly timeless and magical moment. However, Miguel Montargès, an astrophysicist from the Paris Observatory and a specialist in the red supergiant star Betelgeuse, points out that even this celestial event is not as immutable as we might believe. With pedagogical clarity, he explains how, over vast stretches of time, the mechanics of the cosmos will eventually synchronize the movements of the Earth, the Moon, and the Sun. This synchronization would result in a planet perpetually divided into two halves: one bathed in constant daylight, the other shrouded in permanent night. This thought-provoking scenario highlights the dynamic nature of our universe and the potential for dramatic shifts in environmental conditions.
Beyond the distant stars, the documentary brings the focus back to Earth, exploring the terrestrial realm of the night. It showcases a diverse range of nocturnal creatures: bats, owls, tigers, fireflies, whales, and dolphins, representing the 60% of all species that have adapted to thrive in the darkness. The film emphasizes the unique adaptations and behaviors that these animals have developed to navigate and survive in their nocturnal environments.
One segment focuses on the dung beetle, described as "the most powerful insect on the planet," capable of moving objects over a thousand times its own weight. These beetles are drawn to the excrement of mammals, a resource readily available at night. A Swedish researcher explains that these coprophagous scarabs possess two nocturnal compasses: the Moon and the Milky Way. This remarkable ability to navigate by celestial bodies underscores the intricate connection between life on Earth and the cosmos.
The film argues that the concepts of night and light are inextricably linked. While acknowledging that "life appeared at the bottom of the seas, therefore in a totally dark environment," as stated by Romain Sordello, an ecological engineer at the Grande Galerie de l’évolution in Paris, the documentary challenges the notion that daylight is inherently beneficial. Some scientists even suggest that "daylight has become a threat," particularly in areas saturated with artificial light.
The documentary then delves into the fascinating world of bioluminescence. In the deep ocean, where sunlight is absent, many species produce their own light. This bioluminescence is also vital for certain terrestrial species. The firefly serves as a prime example, with the female emitting light from her tail to attract males during the mating season. This natural light is essential for reproduction and survival in the absence of other illumination sources.
The case of the bat is presented as particularly emblematic. Bats possess the remarkable ability to navigate and hunt in complete darkness using echolocation, emitting ultrasonic sounds and interpreting the echoes to create a "sound map" of their surroundings. This allows them to thrive in the dark and navigate complex environments like caves.
However, the documentary emphasizes that the most crucial nocturnal sense is often smell. The elephant is presented as the undisputed "king of the animals" in this regard, possessing an olfactory capacity five times more powerful than that of a human and twice that of a dog. This heightened sense of smell allows elephants to navigate, find food, and communicate in the darkness.
The film culminates with a stark warning about the "existential threat" posed by human light pollution. "Las Vegas is the symbol of the debauchery of artificial lights," the narrator states. The documentary highlights a striking example of the consequences of this excess: in July 2019, millions of grasshoppers were drawn off their migratory path by the bright lights of Las Vegas, leading to a massive infestation in the heart of the city. This event is portrayed as a kind of cosmic justice, a direct consequence of humanity’s disregard for the natural balance of light and darkness.
"Voyage au cœur de la nuit" is not just a visually stunning exploration of the nocturnal world; it is a call to action. By showcasing the vital role of darkness in maintaining healthy ecosystems and the detrimental effects of artificial light pollution, the film urges viewers to reconsider their relationship with light and to embrace the importance of preserving the natural night. The film provides a powerful reminder that the darkness is not simply the absence of light, but a vital element of our planet’s ecological balance, deserving of our respect and protection.
