Sky is a matter of perspective.
Our sky and the spectacle that occurs us above every day and every night and the way it actually appears is a result of the position the Earth occupies in the Cosmos. It is a minute spot nestling among other planets that revolve around a “small” star, at the outer tip of one arm of our galaxy, swirling together with other millions and millions of planets and stars, in the middle of other millions and millions of galaxies, in that infinite space that is our Universe.
We enjoy just a tiny fraction of the sky above our heads. It is so small yet filled with stories, tales and legends. One of these is the story about shooting stars.
Shooting stars: story and explanation
The shooting-star story is a fascinating trip in the world of science through errors, old wives’ tales, incredible discoveries and mysteries still to be solved.
They are given that name but they are not stars (lucky for us)! The bright trail they leave gives us the impression of bright stars falling out of the night sky, but their true nature is anything but that of a star.
The appropriate name for a shooting star is meteor: very small fragments of dust and rock, often just the size of a grain of sand, that enter the Earth’s atmosphere at incredibly high speed and due to friction with the air they become incandescent until they break up leaving behind them an amazing bright trail in this brief process. Some of these rocks that are larger than the others manage to reach the Earth’s surface without fully disintegrating, taking the name meteorites!
The most interesting aspect of shooting stars is where they come from. They are generally residues of asteroids (small rocky bodies that wander through Space) or comets (asteroids that are mainly made of ice) which during their journey through Space leave these tiny fragments behind them.
The Tears of Saint Lawrence
We do not realise it but meteors enter our atmosphere every day! In some periods of the year, however, this phenomenon is much more marked. A case in point is the Perseids, a meteor shower known to us as the Tears of Saint Lawrence, traditionally associated with the night of 10 August. The Perseids (whose name derives from the constellation of Perseus, from which they seem to arrive due to an effect of perspective) are a shower of meteors caused by the passage of a comet called Swift-Tuttle, from the name of two US astronomers. This comet continues relentlessly on its periodic journey passing cyclically close to the Earth. The last time it passed close by our planet was in 1992 and the next “visit” is scheduled for 2126.
If this comet is now a long way off and we cannot see it, how is it that can we see its dust falling to Earth every August?
It seems incredible but it is not actually the comet that “throws” its debris in our direction: we are the ones that go to meet it! Every year, in fact, the Earth travels the same orbit around the Sun and every year in the month of August we pass through the trail of debris that the comet has left each time it passes by!
For many years this meteor phenomenon was associated with unfavourable and inauspicious events, misadventures and misfortunes. The tears represent the actual pain of the Saint’s martyrdom; for the Persians and Indians, they were demons that came down to Earth to create havoc and for the Greeks, it was the accident that happened to the son of Apollo. Negative events caused above all by the lack of knowledge about this amazing astronomical event. This can teach us a lot of things: meteors are like memories, a trace, a reminder of something that happened but that can still tell us a lot. And first and foremost, that we must not be afraid of the unknown, something that is beyond our reach.
Let’s make a wish!
Throughout August, and in particular on the night between 11 and 12 August, go to a place with low light pollution with your friends and your children. Together you can enjoy this magical moment in our small expanse of sky. Together you can do today what the shooting stars represent for us: dream or, if you prefer, make a wish!