This spooky apparition terrified onlookers when it appeared behind the clouds this afternoon in Indonesia.

The ominous dark mass appeared in the sky above the remote island of West Nusa Tenggara - sparking screams of terror from those below.

The glowing circular object resembles a UFO slowly descending from space.

A teacher at the school where it was filmed said children were ''screaming hysterically'' when it emerged at 2.35pm today (April 4) next to holiday destination Bali.

They said: ''This happened at about 14:35 pm, when suddenly the students who were busy playing in the schoolyard, spontaneously screamed hysterically seeing unusual sights, I heard the children's voices, then came out to see and immediately recorded the phenomenon using my cell phone.

''I still don't know what it is. It could be some kind of rainbow. But people were very scared.''

The teacher said that none of the people who saw the incident or anyone who has viewed the video have been able to identify the incident in the sky.

He said it was not the sun being obscured by clouds because the shape was too near and too large to be the sun.

However, the sighting could be a form of ''fire rainbow'' or circumhorizontal arc caused by different clouds interacting with crystals of water trapped in the atmosphere.

Tropical temperatures in the region can also cause sudden movements of clouds and changes in atmospheric pressure, resulting in bizarre scenes.

This spooky apparition terrified onlookers when it appeared behind the clouds this afternoon in Indonesia.

The ominous dark mass appeared in the sky above the remote island of West Nusa Tenggara - sparking screams of terror from those below.

The glowing circular object resembles a UFO slowly descending from space.

A teacher at the school where it was filmed said children were ''screaming hysterically'' when it emerged at 2.35pm today (Wed) next to holiday destination Bali.

They said: ''This happened at about 14:35 pm, when suddenly the students who were busy playing in the school yard, spontaneously screamed hysterically seeing unusual sights, I heard the children's voices, then came out to see and immediately recorded the phenomenon using my cell phone.

''I still don't know what it is. It could be some kind of rainbow. But people were very scared.''

The teacher said that none of the people who saw the incident or anyone who has viewed the video have been able to identify the incident in the sky.

He said it was not the sun being obscured by clouds because the shape was too near and too large to be the sun.

However, the sighting could be a form of ''fire rainbow'' or circumhorizontal arc caused by different clouds interacting with crystals of water trapped in the atmosphere.

Tropical temperatures in the region can also cause sudden movements of clouds and changes in atmospheric pressure, resulting in bizarre scenes.