What's Up? December 2025

Each month I highlight a number of interesting astronomical events and sights which can be viewed with the naked eye. Here we go for December - Jupiter makes a fine appearance and there is the wonderful GEMINID meteor shower to observe.

Geminid Meteor shower

What is a meteor shower?

A meteor shower is a celestial event that happens when the Earth passes through a stream of tiny fragments left behind by an object moving through space. These fragments are usually no bigger than grains of sand. When they hit Earth’s atmosphere at high speed, they burn up instantly, creating brief streaks of light across the sky that we call shooting stars.

On most nights, a few of these meteors appear at random. During a meteor shower, however, the Earth is ploughing through a much denser cloud of debris, so many more meteors become visible over a short period of time.

The Geminids: one of the best meteor showers of the year

The Geminids are widely regarded as the finest meteor shower of the year — not because they are rare, but because they are reliably spectacular.

Unlike most meteor showers, which come from comets, the Geminids originate from an unusual rocky object called 3200 Phaethon. As it orbits the Sun, Phaethon sheds debris, forming a broad trail of material that the Earth passes through every December.

When Geminid meteors enter the atmosphere, they are relatively dense and slow-burning, which makes them appear brighter and more colourful than many other showers. It’s common to see white, yellow, or even greenish streaks, often lasting a second or two longer than average.

At their peak, under dark skies, the Geminids can produce dozens of meteors per hour — sometimes more than one per minute — making them a favourite among astronomers and casual sky-watchers alike.

How to observe

Over the coming few nights 13th, 14th December the Geminids will peak - so take the opportunity if it is clear!

They appear to emanate from the direction of the constellation Gemini - in particular the star Castor. However, just looking EAST will be sufficient and if it helps - in the general direction of the brightest object in the sky, Jupiter! You can't miss it.

Also the radiant point appears just to the left of the constellation Orion -stunning at this time of year.

Find the darkest spot you can, make yourself comfortable and look up into the sky in an easterly direction. There is no need for any optical aids, just stare and you will spot them - maybe one per minute if you are lucky. And don't forget to make a wish when you spot one.

Radiant point of the Geminids - peaking on the nights of 13th and 14th December

Planets

Mercury

The planet Mercury is always difficult to spot as it hides behind the glare of the Sun. However this month is represents the best opportunity to see the elusive planet this year.

Mercury is visible in the pre-dawn sky for the first three weeks of December

Mercury low down in the south east around 7am

Venus

Too close to the Sun this month.

Mars

Wait until next summer!

Jupiter

From mid evening onwards Jupiter puts on a dazzling display. It is bright among the stars of the constellation Gemini (and can help you find the radiant point of the Geminid meteors!). During December the planet will reach high altitudes, helping with the observations.

And don't forget if you are able to observe through a pair of binoculars then you will spot up to four of its moons.

Jupiter mid month around 10pm shining brightly in the east

Saturn

Saturn is observable throughout December among the stars of Aquarius. By the end of the month though it's observing window is reduced. The planet looks red/pink in contrast to the surrounding stars.

Saturn in the south west around 8pm mid month

Enjoy the night sky this month and I look forward to the January night sky too - gosh it will be 2026!