The Perseids are one of the most prolific and best-known of the meteor showers and can be seen in August each year, with the maximum activity on or around 12 August. One advantage of looking for the Perseids is the warmer weather of a typical August night. This makes the shower ideal for beginners and anyone interested in seeing their first meteor.

An image of two meteors in the 1997 Perseid shower. In the centre is a bright fireball and on the left a much shorter Perseid is silhouetted against the summer Milky Way. Image: Rick Scott and Joe Orman Meteors or 'shooting stars' can be seen on any clear dark night (about six per hour), but at certain times of year their numbers peak in ‘showers’, usually named after the constellation from which the meteors appear to emanate. (The point in the sky where the meteors appear to originate is called the 'radiant').

The Perseids' radiant is in the constellation Perseus, just below the familiar 'W' of the constellation of Cassiopeia. At this time of year this can be seen reasonably high in the north-eastern sky at nightfall.

As well as the Sun, nine planets, comets and large asteroids, our solar system contains small particles of material sometimes described as meteoroids. Meteoroids have a high relative velocity with respect to the Earth and so disintegrate rapidly or 'burn up' if they enter the terrestrial atmosphere. The air around them is superheated, ionised and then luminous enough to be seen from the ground – this trail is a meteor.

The red circle marks the 'radiant' of the Perseid meteor shower. Meteors appear to originate from this point, although they can be seen anywhere in the sky. Courtesy of NASA Some meteoroids originate from material ejected in the tails of comets as they pass through the inner solar system. The Perseids were the first meteor shower to be connected to a comet when astronomer Giovanni Schiaparelli noted the similarity between their orbit and the Comet Swift-Tuttle that was observed in 1862. Swift-Tuttle orbits the Sun about every 135 years with its last perihelion (the point at which its orbit is closest the Sun) in 1992 and the next in around 2126. As a consequence the Perseids were highly active in the early 1990s with several hundred meteors per hour at the annual maximum. As the Earth crosses the path of Swift-Tuttle's orbit dust particles released from the comet's tail enter the Earth's atmosphere and burn up, forming meteors.

The rate of meteor activity is usually greatest near dawn because the Earth's orbital motion is in the direction of the dawn terminator. Earth scoops up meteoroids on the dawn side of the planet and outruns them on the dusk side. Courtesy of NASA Even in quiet years, the Perseids have an activity rate that can exceed 100 meteors per hour from a dark site – the rate tends to be highest towards dawn when the observer is on the side of the Earth moving directly into the cloud of meteoroid debris. Perseid meteors also tend to be bright so again the shower is ideal for anyone wishing to see their first 'shooting star' – an observer watching the early morning skies will almost certainly see a number even over a period of 30 minutes.

Most meteors appear as a bright streak of light lasting less than a second but some may be more dramatic and leave behind more persistent trains that mark their path.