Yearly spectacle, most visible in northern hemisphere, is caused by Earth passing through debris of ancient comet
It is time for stargazers to dig out the deckchairs to try to enjoy what is considered to be one of the best meteor showers of the year.
The Perseids are expected to peak on the night of 12 August, although they have been active from mid-July and will continue to be visible for a further couple of weeks.
