Bangs, tremors and even “explosions” were reported to GeoScience Australia (GA) in Victoria and southern NSW as four meteors were believed to have entered the Earth’s atmosphere on Wednesday morning.
Originally the cause of the reports was a mystery to GA, after their equipment did not detect anything on the ground.
“It is somewhat of a mystery, normally an earthquake felt over many, many tens of kilometres … would register on those instruments,” Seismologist Dr Steve Tatham said.
But astronomer Dr Brad Turner at the Australian National University’s Mt Stromlo Observatory in Canberra said their telescope tracking system picked up an object entering the Earth’s atmosphere.
“It appears to be there’s a few largish meteors running into the earth’s atmosphere, when we say large, we think on the order of say a soccer ball or a football,” Dr Turner said.
“Normally when we think of a meteor, we actually think shooting star – something very bright that lasts for a few seconds.
“Those things that we see at night are the size of grains of sand, dust, pebbles, little small rocks, so they just burn up for a few seconds and then they’re gone.”
Dr Turner said the objects were probably from a larger meteor in space that collided with something, causing a few fragments to break off of crash into the Earth.
He likened the impact of the collision with the Earth’s atmosphere to a person “belly flopping” into a pool of water.
“Normally the thing is small enough just to go straight through the water – straight through the atmosphere – and burn up smoothly and not have any problems,” he said.
“But in this case, because it’s so relatively large, it can’t quite cleanly pass through the atmosphere, just as we can’t cleanly pass through the water, and it does a smack into the atmosphere.
“So what’s really happening is kind of like a bomb going off in the atmosphere – and this case it was a series of bombs related to what we believe were four different meteors hitting the Earth.”
He said the initial explosion of the meteors entering the atmosphere would have caused a bright flash, before the meteors were further broken up.
“If this has happened at night, it would have been truly spectacular,” he said.
“You would have seen four large booms at once, then a slew in the order of 30 or 40 different fragments burning up into bright fire balls into the Earth,” he said.