Sky-watchers in Europe could catch a glimpse of a visitor from very deep space this week - the comet PanSTARRS will be bright and visible in our skies until March 18 this week.
Binoculars are recommended to catch the comet, which will be faintly visible on evenings this week, around sunset, according to Sky and Telescope magazine.
The comet will not return in our lifetimes - its orbit around the sun is thought to take 106,000 years.
PanSTARRS is now at its closest to Earth and being lit up brightly by the light of the Sun.
It was first detected in 2011, when it was 1.2 billion miles from Earth.
The comet - a lump of ancient ice - is thought to have come from the Oort Cloud, a cloud of icy objects the edge of our solar system, almost a light year from the sun.
Skywatchers in the Southern Hemisphere captured spectacular images from Mexico, Uruguay, Chile and New Zealand last week.
"Our good views should begin around March 13th, when the crescent Moon is there to point the way," says Alan MacRobert,senior editor at Sky & Telescope magazine.
"Before then the comet was too near the horizon. It will start fading later this week, so if the sky is clear, don't miss your chance."
“The best time to look is about 30 to 45 minutes after your local sunset time. This narrow window of viewing time comes after twilight fades enough for the comet to show through at all, but before it sinks too low and sets.”
“On Wednesday March 13th, you'll see a thicker crescent Moon higher up. Watchers in Europe should look below it by about the width of your fist at arm's length. On Thursday the 14th, look two fists below the Moon and perhaps a bit to the right. After that, the comet will gradually move to the right from evening to evening as it begins to fade.”
Dr Pedro Lacerda, of Queen’s University Belfast says that UK watchers may catch a glimpse at around 6.45: “The coma at the head of the comet should be visible to the naked eye but to see the tail may require the use of binoculars. The most visible features will be its tail and bright coma.
“Those features originate in the nucleus of a comet, a solid lump of dirty ice which, heated by sunlight, sublimates and feeds the diffuse cloud of gas and dust that gives the comet its fuzzy appearance – the coma. Then, light and other particles from the sun push part of the coma away from the nucleus to form the tail which gives comets their spectacular appearance.”
“Comets are important as frozen relics of the formation of our solar system. Before plunging into the inner solar system they spend most of their lives beyond Neptune at temperatures below negative 220 C. For that reason comets retain ices of the ingredients that were present when the planets were born and that are long gone from the surfaces of the much warmer asteroids, for example.”