Fireball - stock image

Fireball (stock image)
An astronomer says a loud bang heard in Rolleston and a red streak seen in the sky over Whanganui at the same time were possibly from a meteorite entering Earth's atmosphere. Retired astronomer Peter Cottrell said it was possible the red streak and loud explosions late Saturday could be from a meteorite or space junk.

"It's possible to get a sonic boom from something coming through the atmosphere at high speed.

"It's a sonic boom because it is travelling faster than the speed of sound."

The red flash seen in Whanganui could have been the meteorite burning up in the atmosphere.

"As soon as it hits the atmosphere there's a lot of friction and friction creates heat and heat creates light as well."

Security guard Nick O'Leary, who was on duty at Whanganui Hospital, said he saw a red streak for a split second just after 11.30pm.

At the same time several residents in the town of Rolleston, Canterbury, reported loud explosions in the area.

Police were unable to identify the source.

Cottrell said the loud bang, or sonic boom, heard in Rolleston would have followed the sighting in Whanganui, Cottrell said.

If it had not burned up completely, finding the meteorite would be challenging. It could be as small as the size of a pebble, but would be dense and heavy.

Cottrell said it was fairly common for meteorites to enter Earth's atmosphere.

Rolleston Fireball
© Google Maps
O'Leary said he was on patrol at the time of the sighting.

"I saw a red flash move across the sky, it was heading north from Whanganui. There was no loud explosion or noise."

O'Leary returned to his his colleagues and said he had seen a meteorite or space junk entering the atmosphere.

"If I had not been looking up at that second I wouldn't have seen it."

About four blasts were heard between 11pm and midnight, in southeast area of Rolleston, giving residents a fright.

Police district command centre spokesman Adam Chambers said police received about a dozen calls between 11.18pm and 11.32pm.

Officers sent to the scene were unable to find what caused the sound.

"The short answer is we don't know," he said.

The Rolleston incident was one of several mysterious bangs reported in recent months.

In June, police in Palmerston North were unable to find the source of a "deep resounding bang", with residents speculating it could be anything from meteors cracking the sound barrier, to claps of thunder, a blown transformer, a garage door slamming, a sparkler bomb or even aliens.

In August, Wellingtonians were woken by "a huge, huge noise", likened to a house going down a hill, or a petrol tanker blowing up.

Again, emergency services were unable to identify the cause.