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"Over 80 years of scientific experience."

The Science of Christmas

Science can help us understand the world around us. But can science help us explain a few of the many wonderful elements of the festive season?

Why do Christmas fairy lights get tangled?
Thomas Edison introduced Christmas lights in 1880 making it safer than candles on trees! However, he introduced a new problem - tangled lights! This has puzzled people for decades, however in 2007 scientists showed that any string or wire over .46 metres is mathematically guaranteed to knot. Why? There’s only one way for a string of lights to be untangled but with a few turns there are endless ways to get them tied up!

Is Santa real?
Of course. On 24th December 1968, astronauts onboard Apollo 8, on return to earth confirmed that "There is a Santa!"   You can track Santa by visiting For 60 years, NORAD and its predecessor, the Continental Air Defence Command (CONAD), have tracked Santa's flight across the globe.

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Why does Rudolph's nose glow?
Reindeer have 25% more blood vessels packed into their nasal cavity than humans. So, when they overheat they get rid of excess heat through their noses to help them regulate their body temperature. This makes their noses glow on thermal cameras but also sometimes makes them look red.

Are Santa's reindeer boys or girls?
Santa has only been seen with reindeer that have antlers, suggesting that they are all female. All male reindeer shed antlers during the winter.

Can Santa's reindeer see at night because of all the carrots left by children?
Reindeer vision is perfect for night flight and adapted to cope with months of living in darkness where they live. The inside of a reindeer’s eye change from gold colour in the summer to blue in the winter which scatters more light to the retina.

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Is the flame on a Christmas pudding blue magic?
A flame on the Christmas pudding is blue, not yellow! Normally alcohol such as brandy is used to provide fuel: ethanol.  Ethanol contains oxygen which gives the flame a blue colour, unlike candles which have hydrocarbons (no oxygen molecules). 

Is mistletoe actually the kiss of death?
A kiss under the mistletoe may have kindled many a festive romance over the years, but the parasitic plant can be the kiss of death for trees.

The Celts and Norse believed there was something magical about this plant, as it stayed green throughout the winter. However, most mistletoe develop their own nutrients by photosynthesis, growing on host trees, sucking up its water and nutrients - once a tree is with mistletoe, it is kissed until death!

Why do we have to wait so long for our turkey?
Cooking a turkey is a balance of chemistry! At a low heat the proteins begin to break down and the meat will cook without too much water loss. However, an oven that is too hot results in contraction of proteins and excessive water loss, causing the turkey to become dry and tough to eat!


Brussel sprouts - love them or hate them? 
Unsurprisingly, December is the month when the most brussel sprouts are eaten in the UK and Ireland, however, the love of them may be down to your genes. Scientists have found a gene which causes some people to find brussel sprouts bitter, while others, carrying a different version, can’t taste it at all.

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Why do Christmas trees last longer now?

Consumers are now demanding natural Christmas trees, that shed fewer needles and are strong enough to hold a mountain of decorations whilst requiring little maintenance. Therefore, scientists have been busy developing the perfect trees for many years. Many trees available from farms, are now selectively bred to last all Christmas and make your tree the perfect centre piece in your cosy home.

Why do we feel sleepy after Christmas dinner?
For many, Christmas dinner can be the biggest meal of the year. It’s not surprising then, that the levels of glucose in the blood is high, which in turn can switch off the brain cells that normally keep us awake and alert, making us feel ready for a nap.

How does skin form on custard?
If custard is allowed to set, sometimes a skin is formed. Water in the custard is tightly bound to the mixture (carbohydrates/cornflour/egg), however, as water evaporates from the top, the custard is unable to draw up more water and (a tasty) dried up custard film forms on top. 

Dreaming of a white Christmas ...

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Silent Night, Holy Night?
Have you ever wondered why it feels so silent after snow fall? Snow is a really good sound absorber, as it accumulates on the ground, air becomes trapped between the individual snow crystals, which help reduce vibration.

Why are snowflakes not frozen raindrops?
Frozen raindrops are actually what we call sleet. Snowflakes are hundreds of ice crystals that fall from a cloud grouped together.

Why is snow white?
When snow is grouped together it appears white because light is reflected by the layers of ice crystal surfaces and this light is scattered back out equally into all the spectrum of colours. Since white light is made up of all the colours in the visible spectrum, our eyes see the snowflakes as white, creating the amazing snow-covered landscapes we love.

Why are snowflakes such pretty shapes and sizes?
The reason they are so beautiful is a complicated mystery… However, cloud temperature and humidity determine the shape and size. The colder the air temperature and higher the humidity around a growing snow crystal, the more intricate and elaborate the shape will be. The largest snowflake was allegedly 15 inches wide, found in January 1887 in Montana, USA.

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