This weekend brings us the peak of a natural display of fireworks to rival the closing ceremony of the Olympic Games. Our planet is ploughing through a stream of dust that creates a spectacle known as the Perseid meteor shower. It is one of the strongest and most reliable of the year and you don’t need a telescope to view them. 

Two Perseids are visible in this photo taken in 2010. Credit: Robin Scagell, Galaxy Picture Library

This celestial wonder has been gradually building up since late July as Earth steadily approaches the densest filaments of the dust, discarded by a comet called Swift-Tuttle in its own orbits around the Sun.

The word “shower’ is a little misleading because you will rarely see more than one Perseid meteor at a time. But if you sit out under a clear, dark sky away from streetlights, you may see one or two every couple of minutes – maybe more. Fortunately the Moon is now a waning crescent in the morning sky and so its light will not be too overpowering for the fleeting flashes as the meteors enter the atmosphere.

Best nights to view will be August 11–12 and 12–13, after which the shower steadily declines in activity, though meteors should be visible for many more nights ahead. More meteors will be seen the later in the night that you are able to view, with most appearing after midnight until dawn when the Earth is turning directly towards the incoming stream. Read Skymania’s advice on how to observe meteors here.

The shower is termed the Perseids because, though the meteors may appear in any part of the sky, if you trace back their paths they all point back to a spot in the constellation of Perseus, known as the radiant. This shows the direction from which the particles are flowing in space. The meteors are actually travelling in parallel paths to each other and the radiant effect is due to perspective, just as parallel lanes of a straight motorway or freeway converge into the distance.

How Perseids radiate from a point in Perseus. Credit: Skymania.com

The Perseids are a popular shower with northern hemisphere observers because the nights are generally warmer than at other times of the year. So if you are having a barbecue or just sitting out in the garden, keep an eye open for these beautiful intruders from space.

You may see a few meteors from another shower, left by another comet, and called the δ Aquarids because they appear to radiate from a spot near the star δ in Aquarius. Or you may see completely random meteors, known as sporadics, which are not linked to any known shower. In all these cases, the meteor is generally no larger than a grain of sand and will vaporise about 100km up in the atmosphere.