Geminids 2021: How to see the best meteor shower of the year over Australia

Set your clocks and get ready for the best meteor shower in the Southern Hemisphere this year.

The annual Geminid meteor shower will peak in the early hours of Tuesday, December 14, but you will see meteors for a day or so either side of this.

While there will be some interference from an almost full Moon, it won't be enough to dampen the show, says Tanya Hill, an astronomer at Melbourne Planetarium.

"So that means you can see them even though there's the glare of the Moon."

This year's Geminids will really reward people who are prepared to get up in the early hours of the morning, around 2-3am, after the Moon has set, says astronomer Jonti Horner of the University of Queensland.

"You'll see a noticeable difference once the sky is darker," he says.

What are the Geminids?

Each year, like clockwork, Earth travels through a stream of debris left behind by an asteroid called 3200 Phaethon.

Bits of dust in the debris trail burn up in our atmosphere, leaving streaks of light in the sky.

While people living in the Northern Hemisphere see more meteors, the Geminids are the best of a handful of meteor showers that can be seen from right across Australia.

"[Most people in the Northern Hemisphere] have to go out in the cold winter to be able to see it, whereas … we may be up early in the morning, but it's much nicer weather," Dr Hill says.

With constant rates of meteors, the Geminids is the most reliable meteor shower of the year, followed by the Eta Aquarids (May) and the Orionids (October).

"The Geminids have actually been the best shower of the year for a few years now," Dr Hill says.

And the light show has become better over time.

That's because the path we take through the debris trail is changing, Professor Horner says.

'The slow drift [of our orbit] is pushing us further into the densest part of the Geminid stream, meaning that, from decade to decade, the rates continue to increase."

When and where can I see it?

You can see the Geminids from anywhere in Australia, as long as they aren't washed out by the weather.

As the name suggests, the meteors appear to come from a point — called the radiant — in the constellation of Gemini above the north-east horizon.

As this point rises above the north-east horizon, you might be lucky enough to spot one or two bright "Earth-grazing" meteors streaking from horizon to horizon.

This occurs at the following local times:

But you'll need to wait until the early morning after the Moon has set and the radiant is the highest in the sky to see the most meteors.

How many meteors will I see where I live?

The further north you live, the better. The Moon sets earlier and the radiant rises earlier so the shower will be higher in the sky at its peak.

Here is a rough guide of the rates with moonset factored in for your location around 2-3am (local).

Tips to get the best view

What makes the Geminids "supremely good" is the fact that the meteors are bright and slow moving, says amateur astronomer Ian Musgrave.

"Because they are moderate to slow moving, if you catch one out of the corner of your eye, it gives you plenty of time to turn your head and watch one," he says.

To catch them at their best, he suggests you: