There's a cluster of stars in our Galaxy that looks rather like a festive fir tree adorned with bright, glistening fairy lights.
NGC 2264 is its official catalogue name, but it has become affectionately known as the Christmas Tree Cluster.
It's a favourite target of astronomers and astrophotographers, and one image in particular caught our attention when it landed in our email inbox during the run-up to Christmas.
This image of the Christmas Tree Cluster was produced by Bill Lowry from Kent, UK, using data he captured from 2–4 January and 26 March 2025.
Look at multiple images of the Christmas Tree Cluster online and you'll see it presented in lots of different colours.
There's even an image of the Christmas Tree Cluster that scientists purposefully coloured green in order to make it extra festive.
More Christmas space science
When producing astro images like this, photographers use different filters to assign colours to different wavelengths of light.
Bill processed his image of the Christmas Tree Cluster using something called the Hubble palette which, as you may have guessed, mimics the colour palette used in images produced by the Hubble Space Telescope.
"I wanted to experiment with the Hubble palette by assigning different colours to the standard SHO, and chose NGC 2264 as a target due to the abundance of data in each wavelength. I ended up with HSO,” Bill says.
"Data-rich targets like this are great for practising your processing skills. My advice is to use narrowband filters with long exposures to capture all that data.
"Ha, OIII and SII can then be colour-mapped however you want: I used red for Ha and blue for OIII, but gold for SII."
The science behind the Christmas Tree Cluster
It may look like a Christmas tree, but what are we actually seeing in this image?
NGC 2264 is a cluster of young stars that are gravitationally bound together. The stars are between one and five million years old, according to NASA, and are located about 2,500 lightyears from Earth.
That means they're so far away, it takes light from these stars 2,500 years to get to us.
To put it another way, the starlight that ended up hitting Bill's camera sensors left the Christmas Tree Cluster's stars during the time of ancient Greece.
The Christmas Tree Cluster's stars are different sizes, too. Some are less than a tenth the size of our Sun, while some are several times as big.
The dark V-shaped patch at the top of the 'tree' is another object, known as the Cone Nebula.
This is a dark nebula, which is a dense cosmic cloud of gas and dust so thick, light can't penetrate it.
The Cone Nebula is 7 lightyears long and packed full of gas and dust, which are the ingredients needed for stars to form.
Scorching hot young stars erode and carve out the shape of the dark nebula, emitting ultraviolet light that illuminates the edges of the dense cosmic cloud.
Capture details
- Equipment: ZWO ASI2600MM Pro camera, William Optics GT-81 IV refractor, Sky-Watcher EQ6-R Pro mount
- Exposure: Ha 10x 1,200”, OIII 21x 1,200”, SII 14x 1,200”, LRGB 40x 30” each, total 13h 20’
- Software: PixInsight
If you're an astrophotographer, send us your images and they could appear in a future issue of BBC Sky at Night Magazine
