Geminids 2019: Don’t miss the last meteor shower of the decade

 The Geminid meteor shower – or just Geminids, for short – is active from from 4 December to 17 December 2019, with fewer activity either side of the peak time.

You could see up to 120 streaks per hour – or 30 to 40 if you are in the city – if the weather permits. If you’re in South Africa, the Geminid meteor shower peaks during the evening hours of Saturday 14 December.

What are the Geminids?

According to the Bronberg Weather Station in Pretoria, the Geminid meteor streams are “groups of meteoroids originating from dust grains ejected from Asteroid 3200 Phaethon,” an Apollo asteroid.

An Apollo asteroid is the name given to a group of near-Earth asteroids discovered by German astronomer Karl Reinmuth in the 1930s. There are 10 485 known Apollo asteroids.

Every time the Earth passes through this stream of dust particles (i.e. meteor stream), left behind by the asteroid, we experience what is known as a Geminids meteor shower, sometimes mistakenly referred to as ‘shooting stars.

A Geminid meteor streaks between peaks of the Seven Sisters rock formation early on 14 December 2018 in the Valley of Fire State Park in Nevada. The meteor display, known as the Geminid meteor shower because it appears to radiate from the constellation Gemini, is thought to be the result of debris cast off from an asteroid-like object called 3200 Phaethon. The shower is visible every December. Photo: AFP/Getty Images/Ethan Miller

Is it visible from South Africa?

Yes, the Geminids are visible from South Africa, as confirmed by the Astronomical Society of Southern Africa (ASSA):

“Grab a deck chair, some coffee, and you may catch a fireball or three from the Geminids.”

The radiant lies at RA 07h 28m, +33° 50′, near Castor (alpha Geminorum), and is dramatically marked in the diagrams. The first shows the view from Cape Town, the second as seen from Johannesburg.

An interactive map of the meteor shower position in relation to constellations can be viewed on TimeAndDate. During meteor activity, toggle the ‘live’ button for real-time data.

How to view the Geminid meteor shower

While South Africans are in a prime position to view the Geminid meteor shower, do note that the visiblity of the Geminds – or any meteor shower, for that matter – depend on several factors.

These include but are not limited to geographic coordinates of observer and elevation, time of the day, city light pollution, the weather and terrain.

Where to look

Find a nice, dark spot – preferably from around midnight to dawn – lie flat on your back if possible, and look up in the north north-east direction towards the constellation of Gemini.

Image via Bronberg Weather Station, Pretoria. Copyright 2011 www.bashewa.com

Your eyes will need about 20 to 30 minutes do adjust to the dark. According to NASA, stargazes would be able to see up to 100 perstreaks per hour in perfect viewing conditions.

“Folks in suburbs will see fewer, 30 to 40 per hour depending on the lighting conditions. And those downtown in major cities will see practically nothing – even though the Geminids are rich in beautiful green fireballs, [city lights] will blot even them out. Dark clear skies are the most important ingredient in observing meteor showers.

NASA

What happens during a meteor shower?

The simplest explanation is that a meteor or meteoroid is a space rock that enters Earth’s atmosphere. The bright streak you see, the meteor’s ‘tail’, is just glowing hot air.

When several space rocks move through our atmosphere, we call it a meteor shower. In most instances, space rocks are debris left behind in a comet’s orbit. NASA explains:

“As a comet gets closer to the sun, some of its icy surface boils off, releasing lots of particles of dust and rock. This comet debris gets strewn out along the comet’s path, especially in the inner solar system (where we live) as the sun’s heat boils off more and more ice and debris.”