50 free Christmas Science trivia questions with answers — science & nature quiz, new questions added Aug 2026.
40 free Christmas Science trivia questions with answers. There is a surprising amount of real science hiding in the Christmas season, and this quiz collects the best of it. Forty questions cover reindeer biology (why Santa's team is probably female, and what colour their eyes turn in winter), why snowflakes have six arms and whether two are ever alike, how mistletoe steals from its host, why poinsettias turn red, and whether turkey really makes you sleepy. There is chemistry in the Christmas cracker, botany in the tree on your floor, astronomy in the star of Bethlehem and the solstice, a bit of medicine in Christmas disease, and some natural history in Christmas beetles, Christmas tree worms and the red crabs of Christmas Island. Easy questions ask what makes snow look white; hard ones want the compound that makes a cracker bang and the year the first electric tree lights were lit. Every answer was checked against Wikipedia's articles on the topics, and each question carries the sentence that supports it.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Reindeer are unique among deer in what way?
Females may grow antlers
Since males shed theirs in early winter, the antlered team on Santa's sleigh is most likely all female.
Q 02When do male reindeer shed their antlers?
Early to mid-winter
Once the bulls are bare-headed, the antlered cows take the top ranks at the best feeding spots.
Q 03A 2011 University College London study found reindeer can see which kind of light that humans cannot?
Ultraviolet
Urine and fur, invisible against snow to us, stand out sharply to a reindeer in the Arctic gloom.
Q 04The reflective layer in an Arctic reindeer's eye changes from gold in summer to what colour in winter?
Blue
The shift in the tapetum lucidum improves vision during months of continuous darkness.
Q 05What causes the clicking sound reindeer make as they walk?
Tendons slipping over bones in their feet
Loud knee-clicking turns out to be an honest signal of body size, a rare case of non-vocal acoustic communication in mammals.
Q 06In the 1823 poem A Visit from St. Nicholas, Dunder and Blixem take their names from a Dutch oath meaning what?
Thunder and lightning
They were later Germanised to Donner and Blitzen; Rudolph did not arrive until 1939.
Q 07Why do most snowflakes show six-fold symmetry?
Ice crystals have a hexagonal structure
Rarely, at around -2 °C, triangular snowflakes with three-fold symmetry can form instead.
Q 08Roughly how many water molecules make up a typical snowflake?
Ten quintillion
That is 10 to the power 19, which is why it is so unlikely that any two flakes are alike.
Q 09Ice is clear, so why does snow look white?
Crystal facets scatter all wavelengths of light
Diffuse reflection of the whole spectrum from countless tiny facets does the trick.
Q 10Who was the first person known to take detailed photographs of snowflakes, starting in 1885?
Wilson Bentley
The Vermont farmer captured more than 5,000 crystals and died of pneumonia after walking home through a snowstorm.
Q 11Snowflake physicist Kenneth Libbrecht was a scientific consultant on which 2013 film?
Frozen
Four of his snowflake photos also became US postage stamps in 2006, with about 3 billion printed.
Q 12Mistletoe is what kind of plant?
An obligate hemiparasite
It photosynthesises but drives a structure called a haustorium into its host to steal water and nutrients.
Q 13How are most mistletoe seeds spread to new host trees?
Birds eat the berries
The name itself descends from Old English 'mistel', long linked to bird droppings on branches.
Q 21Edward H. Johnson, who made the first electrically lit Christmas tree, worked with which inventor?
Thomas Edison
Grover Cleveland sponsored the first electrically lit White House tree in 1895.
Q 22Modern tinsel was invented in Nuremberg in 1610 and originally made of what?
Shredded silver
Lead foil took over for decades in the 20th century because, unlike silver, it did not tarnish.
Q 23Why were candy canes reportedly first hung on Christmas trees?
Peppermint deters rodents and cats
Straight striped peppermint sticks appear in an 1844 confectioner's manual; 'candy-canes' at Christmas are recorded by 1874.
Q 14The red 'petals' of a poinsettia are actually what?
Leaves called bracts
The true flowers are the tiny yellow structures at the centre.
Q 15What does a poinsettia need to turn its bracts red?
Long periods of darkness
At least fourteen hours of dark a night for six to eight weeks, thanks to photoperiodism.
Q 16Poinsettias are often said to be highly toxic. What does the evidence say?
They are not dangerous to pets or children
The plant is native to Mexico and Central America and named for the first US minister to Mexico.
Q 17The idea that turkey makes you sleepy blames which amino acid?
Tryptophan
Turkey actually contains no more of it than other meats; the big meal and the wine do the real work.
Q 18Which two chemicals did Hans van Doorn identify in the 1990s as the source of Brussels sprouts' bitterness?
Sinigrin and progoitrin
Seed companies then bred low-bitterness varieties, which is why sprouts taste milder than they did.
Q 19How are cranberries harvested from flooded bogs?
They float and are corralled
Beds are flooded in autumn for harvest and again in winter to protect the plants from cold.
Q 20Which chemical is used on the friction strip that makes a Christmas cracker bang?
Silver fulminate
Tom Smith added the 'crackle' in the 1840s after hearing a log spit on the fire.
Q 24The Nordmann fir, a favourite Christmas tree, is prized because its needles are not sharp and do what?
Do not drop readily when it dries
It is native to the mountains around the Black Sea and grows to over 60 metres in the wild.
Q 25Old Tjikko, a Norway spruce clone in Sweden, has a root system carbon-dated to roughly what age?
9,550 years
Norway spruce is the original Christmas tree species and the one Oslo sends to Trafalgar Square each year.
Q 26What is the botanical term for a species like holly with separate male and female plants?
Dioecious
Holly leaves can carry six to eight spines a side, though some trees have none at all.
Q 27Frankincense is an aromatic resin tapped from trees of which genus?
Boswellia
Myrrh, its companion gift, comes from thorny trees of the genus Commiphora in the same plant family.
Q 28Astronomers have tried to explain the Star of Bethlehem as a conjunction of which planets?
Jupiter and Saturn or Jupiter and Venus
Kepler wrongly argued a conjunction could spark a nova; modern calculations show the planets never merged into one light.
Q 29In the Northern Hemisphere, the winter solstice, the shortest day, falls on which dates?
December 21 or 22
It happens when the pole reaches its maximum tilt away from the Sun.
Q 30Which great scientist was born on Christmas Day 1642 by the Julian calendar then used in England?
Isaac Newton
By today's Gregorian calendar his birthday is 4 January 1643.