49 Fun Facts About Christmas Science

Reindeer are unique among deer in what way?

Since males shed theirs in early winter, the antlered team on Santa's sleigh is most likely all female.

When do male reindeer shed their antlers?

Mature bulls drop their antlers in early to mid-winter, soon after the autumn rut, so the biggest males are bare-headed by December; younger bulls may keep theirs until early spring.

A 2011 University College London study found reindeer can see which kind of light that humans cannot?

A 2011 UCL team led by Glen Jeffery showed reindeer eyes admit ultraviolet light down to about 320 nm; urine and lichen, invisible against snow to us, stand out sharply in UV.

The reflective layer in an Arctic reindeer's eye changes from gold in summer to what colour in winter?

The tapetum lucidum turns blue in winter as pressure in the eye compresses its collagen, scattering light so less escapes and sensitivity rises during months of darkness; in summer it is golden.

What causes the clicking sound reindeer make as they walk?

Loud knee-clicking turns out to be an honest signal of body size, a rare case of non-vocal acoustic communication in mammals.

Two reindeer in A Visit from St. Nicholas are named for a Dutch oath meaning what?

'Donder en bliksem' is Dutch for 'thunder and lightning'; the 1823 printing had Dunder and Blixem, later Germanised to Donner and Blitzen. Rudolph did not arrive until 1939.

Why do most snowflakes show six-fold symmetry?

Rarely, at around -2 °C, triangular snowflakes with three-fold symmetry can form instead.

Roughly how many water molecules make up a typical snowflake?

A typical snowflake holds about ten quintillion (10^19) water molecules, and with so many ways to arrange them two identical complex flakes are vanishingly unlikely.

Ice is clear, so why does snow look white?

Each ice crystal's facets scatter all wavelengths of light, and after countless reflections within a snowpack the whole spectrum bounces back together, which we see as white; pure ice itself is clear.

Who was the first person known to take detailed photographs of snowflakes, starting in 1885?

Wilson 'Snowflake' Bentley, a Vermont farmer, took the first photomicrograph of a snow crystal in 1885 and captured more than 5,000; he died of pneumonia in 1931 after walking home through a blizzard.

Snowflake physicist Kenneth Libbrecht was a scientific consultant on which 2013 film?

Libbrecht advised Disney's animators on snow-crystal shapes for Frozen (2013); four of his snowflake photographs had already become US postage stamps in 2006, with about 3 billion printed.

Mistletoe is what kind of plant?

Mistletoe is an obligate hemiparasite: it photosynthesises with its own green leaves but cannot live without a host, driving a haustorium into the branch to take water and minerals.

How are most mistletoe seeds spread to new host trees?

Birds such as the mistle thrush eat the sticky berries and wipe or excrete the seeds onto branches; the name is often traced to Germanic 'mist', dung, plus 'tan', twig.

The red 'petals' of a poinsettia are actually what?

The true flowers are the tiny yellow structures at the centre.

What does a poinsettia need to turn its bracts red?

Poinsettias are short-day plants: long periods of darkness, about fourteen hours a night for six to eight weeks, trigger the bracts to turn red through photoperiodism.

The idea that turkey makes you sleepy blames which amino acid?

Tryptophan, a precursor of serotonin and melatonin, gets the blame, yet turkey has no more of it than chicken or beef; the big meal and the wine do the real work.

Which two chemicals did Hans van Doorn identify in the 1990s as the source of Brussels sprouts' bitterness?

Dutch scientist Hans van Doorn found the glucosinolates sinigrin and progoitrin drove the bitterness; seed companies then bred low-level varieties, so sprouts taste milder than they did in the 1980s.

How are cranberries harvested from flooded bogs?

Beds are flooded in autumn for harvest and again in winter to protect the plants from cold.

Which chemical is used on the friction strip that makes a Christmas cracker bang?

A trace of silver fulminate, a friction-sensitive explosive, coats one strip and an abrasive the other; London confectioner Tom Smith added the bang to his bon-bons after hearing a log crackle on the fire.

Edward H. Johnson, who made the first electrically lit Christmas tree, worked with which inventor?

Edward H. Johnson, a vice-president of Thomas Edison's Electric Light Company, lit a tree with 80 hand-wired red, white and blue bulbs at his New York home in December 1882.

Modern tinsel was invented in Nuremberg in 1610 and originally made of what?

Nuremberg's 1610 tinsel was shredded silver, hammered thin and cut into strips; because silver tarnished, lead foil took over in the 20th century until it was phased out over toxicity in the 1970s.

Candy canes get their cooling taste from which compound in peppermint oil?

Menthol, the main component of peppermint oil, binds the TRPM8 cold receptor on nerve endings, so the mouth registers cold without any drop in temperature.

The Nordmann fir, a favourite Christmas tree, is prized because its needles are not sharp and do what?

It is native to the mountains around the Black Sea and grows to over 60 metres in the wild.

Old Tjikko, a Norway spruce clone in Sweden, has a root system carbon-dated to roughly what age?

Old Tjikko's root system was carbon-dated to about 9,550 years in 2008 by Leif Kullman of Umeå University; the visible trunk is young, as the clone keeps regrowing. Norway spruce is the tree Oslo sends to Trafalgar Square.

What is the botanical term for a species like holly with separate male and female plants?

Holly is dioecious, with male and female flowers on separate plants, so only females bear berries and need a male nearby; monoecious species carry both sexes on one plant.

Frankincense is an aromatic resin tapped from trees of which genus?

Frankincense is tapped from Boswellia trees of Arabia and the Horn of Africa, notably Boswellia sacra; myrrh comes from thorny Commiphora trees in the same family, Burseraceae.

Astronomers have tried to explain the Star of Bethlehem as a conjunction of which planets?

Kepler linked it to the triple conjunction of Jupiter and Saturn in 7 BC; others prefer the very close pairing of Jupiter and Venus in June 2 BC, though neither fits the Gospel's moving star.

In the Northern Hemisphere, the winter solstice, the shortest day, falls on which dates?

The December solstice falls on 21 or 22 December (rarely 20 or 23), when the North Pole is tilted furthest from the Sun, giving the Northern Hemisphere its shortest day.

Which great scientist was born on Christmas Day 1642 by the Julian calendar then used in England?

Isaac Newton was born at Woolsthorpe on 25 December 1642 by the Julian calendar, which England kept until 1752; by the Gregorian calendar that is 4 January 1643.

'Christmas disease' is another name for which condition?

Haemophilia B, a deficiency of clotting factor IX, was named Christmas disease after Stephen Christmas, the first patient described, in a paper published in the BMJ's 27 December 1952 issue.

'Christmas beetle' is the common name for beetles of which genus, seen in Australian summers?

Christmas beetles are Anoplognathus, a genus of about 35 large, shiny scarabs that emerge around December in eastern Australia; the Argentine lawn beetle, also out then, is often mistaken for one.

The Christmas tree worm, Spirobranchus giganteus, lives where?

Spirobranchus giganteus bores its tube into living coral on tropical reefs worldwide; its two colourful spiral crowns, which give it the name, are used for feeding and breathing.

In which year did Captain William Mynors sail past and name Christmas Island on Christmas Day?

William Mynors of the East India Company ship Royal Mary sailed past on 25 December 1643 and named it; the island's annual red crab migration to the sea is a famous natural spectacle.

Eggnog may have developed from which medieval hot milk drink curdled with wine or ale?

Posset, hot milk curdled with wine or ale and spiced, was drunk in medieval England as a cold and flu remedy; eggnog likely descends from it, with eggs and later rum added.

Which spirit is traditionally warmed and set alight over a Christmas pudding?

Brandy is warmed, poured over the pudding and lit at the table; the pudding is steamed a second time before serving and often eaten with brandy or rum butter.

The earliest known fruitcake recipe, from ancient Rome, mixed raisins, pine nuts and which seeds into barley?

The Roman mix combined pomegranate seeds, raisins and pine nuts in barley mash; later English fruitcakes soaked dried fruit in rum or brandy, which is why they keep for so long.

Reindeer noses have specialised turbinate bones that do what?

Scroll-like turbinate bones greatly increase surface area inside the nostrils, so, as in a moose, incoming air is warmed and moistened before it reaches the lungs and heat is recovered on the way out.

Ukichiro Nakaya discovered that a snow crystal's shape depends on temperature and on what else?

Supersaturated air produces lacy, ornate crystals; drier air makes them solid and compact.

Reindeer are described as osteophagous, meaning they do what?

Osteophagy is bone-eating: reindeer gnaw shed antlers and bones for calcium and phosphorus that lichen lacks, and in extreme cases chew antlers still on other animals' heads.

The poinsettia is named after Joel Roberts Poinsett, the first US minister to which country?

Poinsett, also a botanist, began shipping the plants to his South Carolina greenhouses possibly as early as 1826; before that it was the 'Mexican flame flower'.

Which Irish passage tomb was built with a 'light box' that lets in the winter solstice sunrise?

Newgrange, built around 3200 BC in County Meath, has a roof-box above its entrance that lets the winter solstice sunrise light the inner chamber for about 17 minutes; Stonehenge's axis frames the midwinter sunset instead.

Early German artificial Christmas trees, a response to deforestation, were made from what?

Feather trees ranged from 5 cm to 2.5 m tall, and their branch tips often carried artificial red berries that doubled as candle holders.

Which president sponsored the first electrically lit Christmas tree in the White House, in 1895?

Grover Cleveland's 1895 tree carried more than a hundred multicoloured electric bulbs; General Electric's first commercial light strings, sold from 1903, came in festoons of eight sockets.

Which caffeinated South American drink is brewed from a species of holly, Ilex paraguariensis?

Yerba mate is brewed from the dried leaves of Ilex paraguariensis, a holly native to Paraguay, Argentina and southern Brazil; yaupon holly in the southeastern US is also caffeinated.

In which city were aluminum Christmas trees first manufactured, in 1958?

Modern Coatings of Chicago made the first aluminum trees in 1958; Aluminum Specialty Company of Manitowoc, Wisconsin, then mass-produced the Evergleam, and A Charlie Brown Christmas (1965) mocked the shiny trees as commercialism.

How wide were the record snowflakes seen at Fort Keogh, Montana, in 1887?

Guinness lists them as 15 inches (38 cm) across and 8 inches thick, reported by a rancher in January 1887; normal aggregated flakes top out around 3 or 4 inches.

What is the sticky coating on mistletoe seeds that glues them to a branch called?

Viscin, a mix of cellulose strands and mucopolysaccharides, makes the seed so sticky that it glues to bark and holds until the seedling's haustorium penetrates the branch.

In AD 274, which emperor made 25 December the birthday festival of the 'Invincible Sun'?

Aurelian, emperor 270-275, founded the cult of Sol Invictus in 274; 25 December, reckoned the solstice in the Roman calendar, became the Sun's birthday, following hard on Saturnalia, 17 to 23 December.

In Turkey, the poinsettia is popularly named after which national figure?

In Turkey the poinsettia is popularly called 'Atatürk çiçeği', the Atatürk flower, after the republic's founder Mustafa Kemal Atatürk; botanically it is Euphorbia pulcherrima.