This is why there was a mysterious blue glow above Sheffield on Monday night
Many people in Sheffield were left confused last night after reporting a mysterious blue glow in the sky.Â
Aliens have been the talk of Sheffield this week after the new series of Doctor Who hit our screens on Sunday.Â
Jodie Whittaker starred as the 13thÂ and first female doctor with Sheffield playing an important role in the first episode.Â
'˜We don't get aliens in Sheffield' was the standout line from the first episode, but many people were left questioning that statement last night.Â
Confused residents across Handsworth, Woodhouse, Beighton, Treeton and even Rotherham reported seeing the mysterious glowing light in the sky.Â
Some residents speculated that it was Northern Lights while others were convinced it was a UFO or something similar from Doctor Who.Â
Nicola Fontana said: 'I saw this last night when I went to take the dogs out. It kept appearing and moving from one side to the other then disappearing again.'
Jake Fraser said: 'There was no noise to it but it kept moving and did the odd flash.'
Andy Senior commented: 'It's the Tardis, trying to find the Doctor.'
Social media sites were flooded with images of the glow at about 11pm with some people suggesting it was the lights from Sheffield Arena.Â
However, it appears there could be aÂ more straightforward reason for the glowing lights.Â
Specialist railway repair '˜tamping trains' are often used by Network Rail to carry out maintenance work on the tracks.Â
According to Network Rail the tamping train is laser-guided, which is why people could see a blue light in the sky.
A Network Rail spokesperson said: 'Tampers and stoneblowers are track maintenance machines that make sureÂ the track is correctly aligned and has a smooth level along the rail.
'TheyÂ help to preventÂ the risk of trains derailing, and ensure smooth, comfortable journeys for passengers and freight trains. These machines generally work atÂ night when no passenger trains are running.'
The cleaner uses lasers to mark out an exclusion zone for the workforce, which could be why people saw a blue light in the sky.Â