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The most dazzling meteor shower of the year will peak this week, festooning the night sky with yellow-tinged streaks as rocks and dust left behind by an asteroid incinerate in the atmosphere.
And the timing is perfect, as the meteors will burst across the sky during a dim new moon.
A composite of more than 100 meteors during 2014’s shower.Credit: NASA/MSFC/Danielle Moser, NASA’s Meteoroid Environment Office
About 50 meteors per hour will flash in Melbourne and Sydney skies, and up to 90 in Darwin as the shower peaks on Thursday night and early Friday morning.
The Geminid meteor shower has long thrilled and puzzled astronomers because the shower originates from an asteroid, not a comet. Comets are icy, dusty, rocky objects that partly melt when their orbit comes close to the sun, hurling off dust particles that become meteors.
The other major meteor shower of the year, the Eta Aquarids in May, originate from a stream left behind by Halley’s Comet which the Earth orbits through.
“Every year, around the same date, we hit that meteor stream,” astronomer and author of the 2024 Australasian Sky Guide Dr Nick Lomb said.
A visualisation of the asteroid 3200 Phaethon, son of the sun god Helios in Greek mythology.Credit: NASA
The parent of the Geminids, however, is an asteroid called 3200 Phaethon. Asteroids don’t normally produce meteor-inducing “tails” such as comets, but the material left behind by Phaethon creates a shower even brighter the Eta Aquarids.
Lomb said this unusual origin of the Geminids could be the reason they’re so spectacular as they burn up at speeds 40 times faster than a bullet (35 km/s) about 80 kilometres above land.
“The shower tends to be very bright, possibly because it comes from an asteroid – or Phaeton, sometimes referred to as a rock comet – giving off small rock particles. These are stronger than normal dust particles [from a comet], so you can get some very bright streaks in the sky.
“This year is a very favourable opportunity to see them because the moon is not in the sky, or is only a thin crescent.”
Earlier this year, NASA research revealed Phaethon’s tail is actually made from sodium gas, not dust like a comet.
That deepened the mystery of how Phaethon left behind the billion tonnes of material that generates the annual Geminid meteor shower each year. Researchers theorise Phaeton was struck by some cataclysm thousands or years ago, such as a collision, that threw off dust and rocks.
We’ll know more in a few years’ time, when Japan’s DESTINY+ spacecraft cruises close to Phaethon to collect data that sheds more light on the unorthodox asteroid.
The best time and places to watch the Geminids
Meteor spotters should look north on Thursday night and early Friday morning for the peak of the shower, although they can appear anywhere in the sky.
It’s best to try to get as far away from city lights as possible.
The interactive site lightpollutionmap.info provides an idea of how much interference you might be dealing with.
In locations with purple shades, urban light risks blotting out many of the meteors, and white spots denote light pollution strong enough to dim even the Milky Way.
For city stargazers, Lomb suggests seeking out a safe park or backyard away from streetlights, putting down your phone for at least 15 minutes and letting your eyes adjust to the dark to watch the shower. There should be about one meteor every two or three minutes at the peak.
Cloud cover may threaten meteor watching in Sydney, Melbourne and Brisbane during the shower’s peak, but Geminid meteors will be visible until December 24, so don’t despair even if you miss the main show.
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