The Halloween isn't over in Japan as spectators and alien hunters marvel at the mysterious green orb that sparked tan ongoing debate. Astronomers say it could be a fireball but alien hunters believe that the green orb is actually an unidentified flying object (UFO).

The mysterious green orb was spotted speeding over Niigata, early on Oct. 31. There were sparks shooting behind the UFO's tail that made it look different from typical shooting stars.

The green orb was spotted in Japan on Halloween night and has attracted a huge number of spectators. Reports say that those who witnessed the speeding green orb managed to film the UFO including a NIPPON TV subsidiary weather camera located in the eastern part of Japan. NHK also released the image as part of its 'spooky sightings' on Halloween night.

Few days after, the debate is still ongoing and people are still trying to decipher the nature of the green orb. Astronomers believe that the anticipation heightened due to the occurring Halloween celebration but there is a more logical explanation for the mysterious UFO that appeared in Japan.

The bright lights that created the orb could just be a 'fireball' in the sky, according to an astronomer. "A fireball is another term for a very bright meteor, generally brighter than magnitude-4, which is about the same magnitude of the planet Venus in the morning or evening sky," said an official from the American Meteor Society in a statement.

The orb could be categorized as a type of fireball called 'bolide' that typically explodes; it then leaves a tail end with visible flash and fragmentation. Another possible conclusion is that the orb could be a part of a space rock or remaining space debris that survived the Earth's atmosphere. But so far, there is no evidence yet to confirm these claims. The lack of knowledge about the orb makes conspiracy theorist and alien hunters believe that the orb is a UFO commanded by little green men.

The mysterious looking orb did not only garner the attention of alien hunters but of scientists as well. But some argue that it just looks like a fireball because it is trying to camouflage itself as a meteor.

What's surprising about the mysterious orb that was spotted in Japan is the interest given to it by both alien hunters and scientists who are all adamant in finding out the truth about the green orb spotted hovering in the sky.