A number of bemused locals have described seeing objects resembling glowing orange 'balls of fire' that hover for a while and then quickly disappear.
Witnesses have described the glowing balls zig-zagging across the sky and moving too quickly to be fireworks, planes or helicopters.
Now experts on the unexplained at The Ashfield Paranormal Investigation Team (TAPIT) have been flooded with calls from eagle-eyed residents claiming to have seen the strange sight.
TAPIT team leader Lee Roberts said checks with East Midlands Airport and local air bases revealed that nothing should have been in that air space at that height at the times the sightings were reported.
Team members have ruled out lanterns and hot air balloons as an explanation because neither can change direction as described and balloons have intermittent flames rather than a constant one.
- Several UFO sightings in Kirkby skies
The mysterious balls were first reported in the skies above Alfreton last month, but they returned on Saturday when Warsop resident Tim Palmer spotted an unusual object at around 3.30pm.
"We were coming from Glapwell, towards Pleasley round-about when I noticed on the left over Shirebrook a large ball of flames," said Tim.
"We pulled up in the lay-by to take a closer look. We thought it was a plane on fire as it was too big for a lantern or a hot air balloon. As we watched, we could see smoke behind it and another small ball following it.
"It was falling out of the sky at a 45 degree angle. After about 10 seconds it went over the horizon. It was very strange as there was no noise."
TAPIT will continue an investigation into the objects and anyone with video footage or pictures should contact the team at bobby_roberts8@hotmail.com or through the website www.tapitcrew.info.
