The Penitentiaries: the snow-white "monks" of the Atacama Desert

In the Chilean Atacama desert, you can find an amazing sight: whole fields of snow and ice pillars stretching towards the sun. Some are only a few centimeters tall, others rise almost 10 meters.

Sometimes the pillars are so close to each other that it can be very difficult or even impossible to pass through them. They have a conical shape and together look like a crowd of priests in white robes with hoods. Due to this similarity, they got their name.

Penitentes is a Spanish word that translates as "penitents". During Holy Week, a procession takes place in Spain, in which priests in robes with pointed hoods participate to perform religious penances.

A cold, dry wind blows through the arid Atacama Desert, which stretches across northern Chile and southern Peru. According to local beliefs, it is this wind that creates these snow-white pillars.

However, scientists have a different opinion. On the Chajnantor plain, which is located at an altitude of 1.2 kilometers above sea level, you can observe the penitentiaries all year round in open areas where there is a lot of sunlight. Their formation process has not been fully studied, but it is believed that the culprit is sublimation, that is, the transformation of ice and snow into water vapor. The sun heats the snow, deepening the irregularities on its surface, then they increase faster and faster due to the fact that sunlight reflects off the walls, speeding up the process.

On March 22, 1835, the famous British biologist Charles Darwin was heading to the Argentine city of Mendoza from Santiago de Chile, and on the way he had to pass through the Pikenech pass in the Andes. He described the region as "conical hills of red granite" and "several vast fields of endless snow." Darwin was the first Western scientist to make records of the penitentes, and his observations aroused great interest in these natural ice sculptures.

On Earth, the penitentes are found mainly in the Andes and the Himalayas, but they have also been seen on other planets and moons. Recent NASA discoveries indicate their presence on Pluto and Europa, a moon of Jupiter. At the same time, science fiction writer Arthur C. Clarke was significantly ahead of NASA when he wrote in his 1982 novel 2010: Odyssey Two:

"All the worlds are yours, except Europe: don't even try to land there."