A comet is breaking up as it nears Earth – and amateur astronomers can observe as it splits up night by night. Here’s how and where to see it.
The comet, called C/2025 K1 (ATLAS), is one of many comets discovered by the ATLAS sky survey for asteroids and comets. It was first seen in May 2025 making its way towards the Sun, which it passed within the orbit of Mercury in early October.
Such a close encounter can often break up comets, which are mostly composed of ice, but the comet appeared to emerge unscathed from its encounter. However, on 10 November the comet’s head was seen to have split.
Comet 2025 K1 is now in the UK sky and can be seen with telescopes and large binoculars near the well-known stars of the Plough (Ursa Major). With medium-sized amateur telescopes the head of the comet is clearly in two or three fragments. Its closest approach to Earth is on 24 November, when it will be at a distance of 49 million km. There is no threat to Earth at this distance and the fragments will remain in an orbit well away from Earth.
The track of the comet is shown on the map below. It is currently beyond the reach of ordinary binoculars, at about magnitude 10, but it should be visible in large amateur telescopes. Amateur astronomers with cameras guided to track the sky can photograph it.
Comets frequently fragment after a close approach to the Sun, but this is a rare opportunity to witness such an event at comparatively close quarters. Comets are unpredictable, so no one can be sure what will happen next.