At about 6:30pm last night, a meteor exploded with a bright flash that was widely seen across eastern Australia.

Stunned onlookers from Sydney to Canberra, and beyond, reported seeing the explosion light up the night sky in colourful streaks ranging from blue to green to orange.

In technical terms, the fireball was a “bolide”. Bolides are meteors that are not only brighter than the planet Venus, but which can also seen to explode or break up as they enter the atmosphere. They are rare to see.

So where might this fireball have come from?

First, what it wasn’t

The first point to make is that this fireball was not a piece of space junk. It was moving very fast, likely in excess of 30 kilometres per second.

Space junk, in contrast, enters Earth’s atmosphere at slower speeds of roughly 8km per second. In addition, such junk enters Earth’s atmosphere at a very shallow angle, meaning it can streak from horizon to horizon over the course of a minute or more.

The second point to make is that this fireball was definitely not from the Eta Aquariid meteor shower, which is visible between mid-April and late May. Meteor showers consist of debris moving through space, crashing into Earth, and coming from a specific direction. Meteors in a shower appear to........

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