Leo Enright, a space commentator, said fuel ejecting from rockets is a normal occurrence.
He said if the fuel is kept in the rocket there is a danger that it will explode and release debris, so ejecting fuel is standard practice for space companies.
Mr Enright explained that lighting conditions are the reason why the spectacle had not been noticed before across the island of Ireland.
“It’s all to do with lighting, and also honestly seeing anything from Ireland is a challenge,” he said.
“So I’m sure it’s happened in the sky and we just couldn’t see it because of cloud.”
Mr Enright said: “The reason why Ireland is quite vulnerable [to space debris] is that we are, generally speaking, at the highest point on the map of the launch trajectory of the rockets out of Cape Canaveral [in Florida].”
This week astronomers and other experts from across the globe met in Westport, external, County Mayo, to examine the challenges of light pollution and explore solutions.
BBC News NI has contacted AirNav Ireland for comment.