A week on from the mysterious sighting of a UFO by pilots flying over Ireland, there's still no confirmation as to what it was that sped through the night sky.
Could it have been a rogue aircraft in unauthorised airspace? Or some junk thrown into the depths of space by humans?
We still don't know - but here are the three main possibilities:
As you can hear in the air traffic control recording, the captain of a British Airways flight asked if there were any military exercises taking place in the vicinity of the sighting.
The response from controllers was that they weren't aware of any military activity and no other aircraft were shown on radar.
But that doesn't necessarily mean this possibility can be ruled out.
In 2003, then US President George W Bush boarded Air Force One near Washington DC on a top secret mission to visit American troops stationed in Iraq.
Given the extreme risk of taking the president into a war zone, it was critical that no one knew he was coming.
This meant the crew had to fly a distance of 10,000km, taking 10 hours and flying over the busy airspace of the United Kingdom, France and Germany, without the iconic giant blue and white aircraft being spotted by anyone.
Most of Air Force One's communication equipment was switched off, and the crew identified themselves to air traffic control as a much smaller Gulfstream private jet. This would be their cover when they appeared on radar screens during the journey.
The entire mission was almost called off when the presidential aircraft flew over London.
An observant pilot jumped on the airwaves.
"Did I just see Air Force One?" they asked
There was some silence, then the Air Force One captain replied.
Luckily for the president and his team, the British Airways pilot took his observation no further and President Bush landed in Iraq before anyone even knew he was coming.
Air Force One, one of the most identifiable of all aircraft in the world, was flying within UK airspace and none of the air controllers had any idea.
This theory is so far stacking up to be the most likely explanation.
One of the pilots who witnessed the lights shared his thoughts on the cause.
"It may have been a meteor or some other object making some sort of re-entry. [It] appeared to be multiple objects heading on the same trajectory. It was very bright," he said.
Additionally, newly emerged video filmed in Ireland at the same time of the sighting seems to back this up. The object appears to break up and fade into thin air as it streaks across the night sky.
Sandy Laverty, the driver who captured the lights on her dashcam, said it was much larger and brighter in real life and said she didn't hear the story about the pilots until the following day.
A letter to the editor published in the Irish Times by a Mr John Bergin says the object was a UFO because it is exactly that, an unidentified flying object. If it turns out that it was being used by alien lifeforms, then it will lose that title.
Loman Ó Loingsigh also wrote to the paper with his thoughts. He said the little green men are already here.
"They have been helping people cross the road safely for years," he said.
It does seem likely that if little green men were to make anywhere on Earth their home, it would be Ireland.