Skygazers across the UK have a chance to witness the Northern Lights until Saturday.
The Met Office forecast suggests the phenomenon, also known as the Aurora Borealis, could be visible to the naked eye along the northern horizon from Scotland, where skies are clear.
The Northern Lights may also illuminate the sky in Northern Ireland and northern England.
A minor enhancement to the aurora oval - which determines the range of polar lights - means the dazzling display is visible further south.
It is usually associated with Scandinavian countries in Europe, but can sometimes be seen in the UK.
People reported sightings across the nation on Wednesday - from as far south as Cornwall, as well as in Greater Manchester, Northumberland and the Lake District.
Lancaster University's AuroraWatch, run by the Space and Planetary Physics group, issued a "red alert" on Wednesday, meaning "it is likely that aurora will be visible by eye and camera from anywhere in the UK".
The activity is expected to start subsiding from Saturday.
How can you see the phenomenon?
Professor Don Pollacco, of the University of Warwick's department of physics, said it would be difficult to predict exactly where the Northern Lights could be seen, because conditions change rapidly.
"However, one thing is for sure, and that is that you are unlikely to see them from a brightly lit city environment - you need to go somewhere dark and look towards the northern horizon [look for the North Star].
"So, you would preferably be in the countryside away from street lights. Of course, it also needs to clear."
Explaining what the lights are, Professor Pollacco added: "The Northern Lights [Aurora Borealis] are caused by the interaction of particles coming from the sun, the solar wind, with the Earth's atmosphere - channelled to the polar regions by the Earth's magnetic field.
"It's actually a bit like iron filings and the field of a bar magnetic.
"The solar wind contains more particles when there are sun spots, as these are regions on the sun's surface where the magnetic field is interacting with the plasma in the sun, and the particles can be released.
"Once the particles are channelled into the Earth's atmosphere they interact with molecules and have distinctive colours and patterns such as light emissions that look like curtains or spotlights.
"These shapes over change quickly over timescales of minutes/seconds."
According to the Royal Observatory Greenwich, different gases determine what colours light up the sky, with nitrogen and oxygen being the primary gases in Earth's atmosphere.
Green in the aurora is a characteristic of oxygen, while purple, blue or pink hues are caused by nitrogen.
A deep red can sometimes be seen when the aurora is "particularly energetic", as a result of very high altitude oxygen interacting with solar particles.