2023 Geminids Meteor Shower – what’s a Rock Comet?

One of the major meteor showers for the year is happening soon and in 2023 there’s a New Moon too!

What is a meteor shower?

As the Earth moves around the Sun each year, there’s more than just the change of seasons and the annual opportunity to light the candles on a cake and sing the birthday song.

There’s also  patches of dust and debris in the path of the Earth’s orbit that have been left behind often from passing comets. As the Earth passes through these left behind patches each year, small particles of these debris enter the Earth’s atmosphere and burn up, producing a bright streak in the sky called a meteor. (A meteorite is a big of space debris that’s big enough to survive the firey journey through the atmosphere and impact on the Earth’s surface.)

As these patches well known, we can predict both when and where in the sky they’ll appear. The name of the various meteor showers refer to where in the sky they appear from.

The Geminids appear in the constellation of Gemini.

How do I observe a meteor shower?

Our advice would be to get away from city and suburban lights! Background lights from heavily light polluted sites are going to drown out meteors. They’re best observed either just with your eyes or via a pair of binoculars. There’s no need to use a telescope.  It’s a good idea to see if you can observe meteor showers after midnight as your spot on the Earth is facing towards the direction our planet is travelling towards. Here’s some binoculars that would make ideal companions to take meteor spotting.

You can photograph a meteor show by using a DSRL camera on a tripod and taking a long exposures.  A wide angle lens like these Samyang models would work well for capturing meteor showers.

What am I going to see?

The behaviour of meteor shower on any particular evening are hard to predict. They’re probably described as a “could be spectacular, but who knows??” type of event! As a meteor shower is the Earth heading into a cloud of space debris, it will appear as meteors emanating outwards from a single region of the sky.  You might see a meteor every minute or two, up to several a minute or even a few appearing at the same time. They also happen over the course of the evening an can occur over a couple of nights. The images presented in the media are not what you’re going to see with your eyes  – but seeing a meteor shower in full bloom yourself is something you’re never going to forget.

The Geminids Meteor shower as captured via Shao Miao


When can I see the Geminids in 2023?

Head outside around midnight on the Thursday the 14th of December 2023 Sydney time and look toward the north and north-west part of the sky. Make yourself comfortable. See if you can find two bright stars in the constellation of Gemini called Castor and Pollux.  Geminids meteors will appear from around that region.

General region where the Geminids meteor shower will appear around midnight on the 14th of December 2023, Sydney time

Make yourself comfortable and wait. Hopefully you’ll see a very special display.

The reason why a New Moon coinciding with the Geminids this year is that without the light from the Full Moon it will be easier to see fainter meteors.

What’s special about the Geminids?

The Geminids are one of the best meteor showers of the year.

As mentioned above, meteor showers are normally the result of the Earth running in the debris left behind from a comet as it orbits the Sun. Why isn’t this collection of dust and tiny particles also orbiting the Sun if it’s in the same orbital plane? What happens is that when a comet gets close to the Sun, the materials in the comet’s main body or nucleus heats up and turn straight from a solid ice into gas. This process also carries off other small bits of dust and rock that make up the comet’s nucleus. This material is pushed away from the direction of the comet and while they maintain the general orbits, they drift away over time.  This collection of material is called a meteor stream and is colliding with these is what causes most meteor streams. Many of the meteor showers astronomers are familiar with have be

However, the Geminids are mainly caused by a critter with the name of 3200 Phaethon, about 5 km in diameter,  is a also referred to a rock comet. 3200 Phaethon was only discovered in 1983 and was the first asteroid to be discovered from images taken from a spacecraft.

Rather than being a typical loose collection of dust, tiny particles and ice that most comets are made up of, 3200 Phaethon is more likely a hard, rocky asteroid who’s steeply inclined orbit more resembles a comet. In fact it comes closer to the Sun than any other recognised asteroid. The heating of the normally cool asteroid as it get closer to the Sun heats up the hard surface and the Sun’s radiation pressure pushes off any small hard and dry dust flakes off the asteroid’s surface into space. This is also quite a rare body and it’s only been in the last few months that exactly what 3200 Phaethon is composed has been confirmed. If you’d like to read more about some fascinating astro detective work, find out more here.

This illustration depicts asteroid Phaethon being heated by the Sun and venting Sodium gas into space. (Image via NASA/JPL-Caltech/IPAC)

So make sure you head outside and give yourself an early Christmas. See a cool meteor shower knowing the white streaks appearing in the early morning sky are time flakes of a rare asteroid burning up as they hit the Earth. Now THAT’s a Christmas light show!


Earl White






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