With no bright moonlight to spoil things, 2023 could be a vintage year for summer’s strongest meteor shower. Paul G Abel tells us how to make the most of the Perseids
It may often seem that amateur astronomy is dominated by large telescopes, expensive imaging kit and smartphone apps, but in fact there is still one branch of amateur astronomy that requires practically nothing at all: meteor observing. Although there can be sporadic meteors all year round, we usually observe them when well-established showers are underway. And perhaps the best-known annual meteor shower of them all, the Perseids, takes place this month. With the Moon only a slender waning crescent and very little moonlight to drown meteors out, the prospects for this year’s shower are looking good.
The Perseid meteor shower gets its name from its radiant (the point in the sky where the meteors appear to come from) being in the constellation of Perseus. In much the same way, the radiant of the Geminid meteor shower lies in Gemini, the Leonids have their radiant in Leo, and so on.
As one of the most prolific meteor showers, the Perseids feature in folklore and myth. It used to be said that the Perseid meteors were the ‘tears of Saint Lawrence’, as some believed they were the sparks from the fire on which Saint Lawrence was martyred in 258 AD. We had to wait until 1866 for the real cause of the shower to be identified: that was when Italian astronomer Giovanni Schiaparelli correctly identified comet 109P/Swift–Tuttle as its source, which passes through the inner Solar System every 133 years.
What are meteors?
It is the dust in a comet’s tail that becomes meteors. As a comet approaches the Sun, the increasing heat causes volatile material on the comet’s surface to evaporate, taking dust with it to create the tail of particles. A comet’s tail can be quite spectacular to observe, and out in space the stream of dust can stretch much further, spanning the distances between planetary orbits. For comets in short orbits, this process happens fairly frequently and, as a result, multiple debris streams from different comets are generated, the streams orbiting the Sun just as the planets do.
When Earth passes through one of these streams, the particles within it hit our atmosphere and burn up in it, becoming meteors. In the case of the Perseids, most of these particles are the size of sand grains, but it is not uncommon for larger piece
