Comet Neowise, which was discovered in late March by a space telescope, is going to be visible in the UK with the naked eye throughout July.
The comet is rare in that it survived a close encounter with the sun, passing at roughly the same distance as Mercury.
During its closest approach to Earth Neowise will be about 64 million miles away – or about 400 times further away than the moon.
A Nasa spokesperson said: “A comet has suddenly become visible to the unaided eye.
“Comet C/2020 F3 (NEOWISE) was discovered in late March and brightened as it reached its closest approach to the sun, inside the orbit of Mercury, late last week.
“The interplanetary iceberg survived solar heating, so far, and is now becoming closer to the Earth as it starts its long trek back to the outer Solar System.
“As Comet NEOWISE became one of the few naked-eye comets of the 21st Century, word spread quickly, and the comet has already been photographed behind many famous sites and cities around the globe.”
The best way to see the comet is to look for the constellation known as The Plough or The Big Dipper.
You will need to get up early – in mid-July Neowise is most visible around 80 minutes before sunrise, so shortly after 3.30am.
On a clear night, if you are in an area with little light pollution, you should be able to see the comet if you look eastwards towards The Plough, about 10 degrees above the horizon.
Space.com advises: “Your clenched fist held at arm’s length measures approximately 10 degrees in width. So, on these three mornings, the head of Comet Neowise will appear about ‘one fist’ up from the north-east horizon.”
The comet passes closest to Earth on 23rd July, when it will be below and just to the right of The Plough.
On 25th July it will be directly under it, before continuing to move west and slightly upwards.
You do not need binoculars to see the comet, though they will enhance the view.