Milky sky and cars covered in fine red dust: it is the sand from the Sahara that periodically “rains” on Italy. And which promptly unleashes the imagination of conspiracy theorists. The more curious, in fact, have noticed that in many cases the Sahara dust collected in the street is magnetic, a behavior that has been attributed, in various ways, to chemtrails, to the presence of nanorobots and microsensors with which we are monitored, and other imaginative conspiracies. And which, obviously, has nothing unusual about it. Let's see why.
Sahara dust
In the meantime, let's take this opportunity to learn something about nomenclature. What we call Sahara sand is in fact, more correctly, a powder: just pass it between your fingers to realize that the particles that compose it are much finer than the grains of sand we find on our beaches. The term sand should therefore be reserved for grains measuring between 0.06 and 2 millimetres, relatively large compared to those arriving in our cities from the Sahara desert, which generally have dimensions of less than 20 microns. This is why they are defined as dust, and the difference is not purely linguistic: only these microscopic particles can remain in the atmosphere long enough to regularly make journeys of thousands of kilometres, such as those necessary to reach our cities from the African continent.
Magnetic dust
The conspiracy theorists are not wrong about the magnetic properties of the red dust coming from the Sahara. The mistake, however, is thinking that there is something strange. Iron and iron minerals are a common component of rocks found in many areas of our planet. And when these are crumbled by geological and atmospheric phenomena, the minerals in question become part of the sand and dust present on the ground.
In the case of Sahara dust, it is a material produced by wind erosion. And it is precisely the reddish color that betrays the great abundance of magnetic minerals within it: it is in fact mainly due to hematite, a weakly magnetic iron mineral, and to a lesser extent to magnetite, strongly magnetic. On the journey it takes to reach Italy, obviously, the dust from the Sahara also encounters polluting particles produced by man.
But their presence is minimal compared to that of the minerals present in the rocks from which it originates. And the fact that it is attracted by a magnet, therefore, is absolutely natural, and not due to chemtrails or other mysterious magnetic materials introduced by man. Even more so since Sahara dust is a fundamental source of iron for many ecosystems on the planet, from the Atlantic Ocean to the Mediterranean Sea, where bacteria and phytoplankton thrive thanks to the supply of micronutrients, in particular iron, transported by the winds and coming from desert dunes.