Herts academics explain the science and the mythology behind the Geminids - the ‘king of meteor showers’

The Geminids, often described as the “king of meteor showers”, will peak on the night of December 13 into the morning of December 14, producing up to 100 meteors per hour.

Dr William Alston, astronomer and Senior Lecturer at the University of Hertfordshire’s Centre for Astrophysics Research (CAR), said the Geminids “are one of the best meteor showers of the year and are thought to be intensifying every year”, making them worth watching out for.

This year, the meteor shower is active between 4-20 December and will peak on the night of 13-14 December.

He said: “Under ideal, dark-sky conditions, a peak rate of up to 100 meteors per hour is possible. If you’re in a reasonably dark spot - away from heavy city lighting - you might expect 50-70 meteors per hour around the peak, though the actual visible count could be lower depending on time of night, radiant height (where the individual shooting star paths appear to come from), moonlight, weather and light-pollution.

“Fortunately, this year the peak will occur when the Moon is a waning crescent, so viewing conditions are reasonably favourable.”

This spectacular astronomical event gets its name from the constellation Gemini, where the meteors appear to radiate from.

Dr Alston said: “In the naming system for meteor showers, you pick the nearest distinct constellation or bright star and add ‘-ids’.”

While most meteor showers come from a comet, the Geminids are created by debris from an asteroid known as 3200 Phaethon, which Dr Alston says, gives the debris stream somewhat different characteristics, including multiple colours.

He said: “A meteor shower happens when the Earth passes through a trail of small pieces of debris - dust, sand-sized grains or small rocks - left behind in space by a comet or asteroid. These pieces, called meteoroids, enter Earth’s atmosphere at speeds around 30 km/s (19 miles per second), burn up and produce bright streaks of light that we call meteors or ‘shooting stars’.

“A meteor shower occurs when lots of these pieces of debris cross Earth’s path at roughly the same time each year, so you’ll see a higher rate of meteors coming from roughly the same part of the sky.”

Dr Alston likens the meteor shower radiant to “the vanishing point of a train line” due to perspective.

He said: “Just as parallel train tracks appear to converge at a single point in the distance, the parallel paths of meteoroids entering Earth's atmosphere appear to originate from a single point in the sky. This is actually a trick of perspective; in reality, the meteors follow parallel paths through space.”

Although the Geminids are known as the “king of meteor showers” because of their abundance and their reliability, they are relatively young and was first recorded in the 1830s, says Dr Ceri Houlbrook, Senior Lecturer in Folklore and History at the University of Hertfordshire.

She said: “This means unlike other meteor showers, they do not have centuries of beliefs and folklore behind them. However, the Geminids are linked to Greek mythology. Their name comes from the constellation Gemini, where the meteors appear to come from. Gemini, Latin for twins, is named for its two brightest stars, Castor and Pollux, the twin sons of Leda. In typical mythological fashion, theirs was an unconventional family. Castor was the mortal son of the king of Sparta, while Pollux was the immortal son of Zeus.”

Dr Houlbrook said the asteroid Pantheon – the source of the Geminids – is also named for Greek mythology.

She said: “Phaethon was the son of Helios, god of the Sun. He was also an impetuous young man, who convinced his father to let him drive the sun chariot. Losing control of the horses pulling the chariot, he drove the sun close to the Earth, scorching it, and then too far away, causing it to freeze (hence why we now have deserts and tundra). Zeus intervened, striking Phaethon dead with a thunderbolt.

“Coincidentally, the Geminids normally peak in mid-December, a week before the Winter Solstice, which is when we celebrate the rebirth of the Sun.”

Dr Alston says what makes meteor showers exciting is that each meteor is unique “and you never know exactly where or when the next one will streak, what colour it might be or how long it will last on the sky”.

He said: “Meteor showers are a universal spectacle and accessible to everyone.

“Knowing that each meteor is a tiny bit of space dust burning up in our atmosphere gives us a sense of connection to the wider cosmos. Like any astronomical event, they offer a moment of pause in our busy lives.”

As with most “naked-eye” astronomy events, Dr Alston advises the best place to observe the meteor shower is a spot with as little light pollution as possible.

He said: “You will not need a telescope or binoculars to enjoy the Geminids. Let your eyes adapt to the dark over a 20-30 minute period and avoid looking at bright smartphone screens or bright lights.

“Aim to watch during the hours after the Gemini radiant has risen - typically the later evening into the early‐morning hours gives more meteors because you are looking into the direction of Earth’s motion. Fortunately, the Geminids are one of the major showers that shows good activity before midnight.

“While you can certainly observe from many places in the UK, your chances improve the darker the skies. Some recommended places include national parks, designated dark-sky areas, and the countryside - away from streetlights. Even just being somewhat away from major towns or cities helps. If the weather is clear and skies are dark, you may get an excellent view of the Geminids.

“Taking time to look upward, under dark skies, can be a refreshing reminder of our place in the Universe.

“And finally, don't forget to wrap up warm on these cold winter nights!”

Study astrophysics or folklore at the University of Hertfordshire.