WORLD WATCH

Our collection of amazing images from around the world.

A Perseids meteor streaks across the sky above a campsite at the Negev desert near the city of Mitzpe Ramon in August, during the Perseids meteor shower, which occurs every year when the Earth passes through the cloud of debris left by the comet Swift-Tuttle.

The comet is 26km across – larger than the estimated size of the Chicxulub impactor thought to have caused the Cretaceous-Paleogene extinction event. When Swift-Tuttle circles the Sun, dust spreads into a trail around its orbits. Every year, Earth passes through the debris trails and pieces interact with our atmosphere to create the Perseids meteor shower. The debris enters Earth’s atmosphere at about 60km per second relative to the planet. Most are the size of sand grains and almost none hit the ground.

Comets are usually named for their discoverers, or for the name of the observatory used in the discovery. Lewis Swift and Horace Tuttle discovered this comet independently – on 16 July, 1862 and 19 July, 1862 respectively. It makes repeated close approaches to the Earth, and it was once thought there was a likelihood that the comet could impact the Earth on 14 August, 2126. However, subsequent observations led to a recalculation of its orbit and it was found to be sufficiently stable and no immediate threat. A close encounter with Earth is predicted for the comet’s return to the inner Solar System in the year 3044, with the closest approach estimated to be 1.6 million kilometres.