A red sky, two cosmic wonders. The photographer Alessandra Masi immortalized an extraordinary spectacle on January 1, 2025 in Roccolo Park in Pieve di Cadore (Belluno)a place dear to many for its pristine beauty. This image, chosen by NASA as Astronomy Picture of the Day (APOD) on January 7, 2025, tells the vision of aNorthern Lights (rare event, in our latitudes, but expected in those days) accompanied by a SAR arc (Stable Auroral Red), an even less common phenomenon.
What are the Northern Lights?
The Northern Lights are a luminous dance that occurs when charged particles from the solar wind interact with the Earth’s magnetospherecolliding with gases in the atmosphere. The colors we see, like the deep red aurora in the photo, come from oxygen (red and green) and nitrogen (red and blue). Find out how the Northern Lights are born.
The image captures the luminous pillars above the snow-capped Marmarole, a breathtaking meeting between sky and earth that becomes even more extraordinary at unusual latitudes such as the Italian ones.
And what is the SAR arc?
In addition to the aurora, the photo shows a SAR arca red glowing structure in the ionosphere. Unlike the “traditional” aurora, the SAR arc is generated by streams of charged particles flowing along the Earth’s magnetic field.
When this happens there is a release of thermal energy in the Earth’s upper atmosphere, which produces the arcs we see: the energy in fact ionizes the oxygen atoms responsible, here too, for the red color we see in the upper part of the auroras. However, it is a rare phenomenon, and in many respects still little known, which highlights the complexity of the interaction between the Sun and the Earth.
A gift from Cadore
For Alessandra Masi, the Roccolo Park it is a special place: «Every time I look out onto this viewpoint, I feel a profound connection with the nature that surrounds me». This space, with its view of Lake Centro Cadore, gave observers an unforgettable evening and an image that combines science and poetry.
Observing these phenomena at such low latitudes reminds us how precious our planet is and how much there is still to discover between heaven and earth.
