Noctilucent clouds and aurora photographed over Caithness
An amateur astronomer has captured rare images of a night sky lit up by unusual high altitude clouds and the Aurora Borealis.
Macieji Winiarczyk, a member of Caithness Astronomy Group (CAG), photographed the noctilucent clouds and Northern Lights earlier this month.
The images were captured over Caithness and have been used to create time lapse footage.
US space agency Nasa has featured the time lapse on an astronomy website.
On the site, astronomers said it was rare to see the clouds and aurora individually.
Noctilucent is the Cloud Appreciation Society's cloud of the month for August.
The society said they form in a region of extreme cold in the atmosphere about 30 to 50 miles (48-85 km) from the Earth's surface.
On its website it said: "Noctiulcent clouds can only be spotted during the summer months and then only occasionally.
"They always have an eerie blue, rippled appearance and the processes behind their formations are far from clear."
The aurora happens when the Earth's magnetic field is battered by storms of charged particles from the Sun.
Some of the best places in the UK to see the "lights" are in Scotland and include the Northern and Western isles and Caithness and Sutherland.
Aberdeen's associations with the Aurora Borealis are celebrated in the local song, The Northern Lights of Old Aberdeen
In the past, the city's tourist information staff have been asked when the "lights were turned on" by visitors unsure of what causes the displays.