CHRISTMAS EVE IS a time of magic and wonder. But facts are facts, just as much on 24 December as they are on every other day of the year.

For a special installment of FactCheck, we’re taking a look at a question that will be puzzling millions of curious minds around the world tonight, as they gaze out the window, and sneak downstairs:

Can Santa really deliver all the world’s presents in one night?

THE FACTS

Source: PA Archive/PA Images

How does he process all those letters?

With the help of the elite, enigmatic, 1,000-strong Elf Secretariat, Santa Claus receives, triages, and processes an estimated 45 million letters and emails each year.

It’s understood that around 56% of these involve requests for intangible gifts or favours (so-called “wish-granting queries”).

According to statistics published on his official website, about half of the remaining 20 million requests are acceded to, based on a behavioural determination (the famous “N/n designation”).

In recent years, this has left on average around 10 million presents wrapped, stamped with a name and address, and barcoded, by 24 December.

Interestingly, Santa Claus’ workload has been cut over the past several decades, due to a fall in requests attributed to a spate of unfounded rumours about his existence.

How does he find out who’s naughty or nice?

Source: Virginia Mayo/PA Images

The Elf Secretariat makes an “N/n designation” in millions of cases each year, based on an analysis of:

Correspondence from parents

A network of volunteer informants (uptake is highest in the teaching and retail sectors)

Operation Coal – year-round consultation with law enforcement agencies and grandparents throughout the world

In recent years, Santa Claus has allowed an online “self-declaration” to be taken into account, in the case of children with a verified past record of “100% Nice”.

Each child’s N/n designation is then stored in a central database, which is protected by 64-bit encryption.

Senior officials in the Secretariat check the list twice on 23 December, and a definitive version of the database is securely exported to Santa’s mobile devices by Christmas Eve.

How does he carry all those presents around the world?

Building on a blueprint for the notorious Antonov An-225 Mriya Soviet cargo aircraft (the document was smuggled over the Finnish border during the Cold War) Santa’s Lightspeed Aircraft One (SLAI) has a payload capacity of 500,000 kilogrammes.

The average weight of a present on board the SLAI is half a kilogramme (the increased prevalence of digital video game download codes and gift cards has drastically reduced that figure in recent years).

But the fact remains that Santa Claus can carry, at once, a maximum of one million gifts.

There’s a commonly held misperception that he transports all 10 million gifts in one journey, but a brief look at the physics shows that this hypothesis is untenable.

A Wikileaks data dump in January revealed the reality: On the night of Christmas Eve, the SLAI makes 10 separate trips to various sectors of the world, returning to base in the Arctic between each one. Which brings us to the next question:

How does he make it around the world in one night?

Source: Wikimedia Commons

This is a problem that has perplexed aeronautics experts for decades. The answer lies in a combination of basic demographics, next-generation technology, and carrot juice.

Firstly, 10 million presents does not mean 10 million house visits.

The minimum possible number of children designated “n” in a given household is, by definition, one.

And while the average naturally varies between countries (the figure is 1.6 children per household for Ireland, according to 2011 CSO data), it hovers around 3 children per household in the developed world.

And this doesn’t take into account institutions such as hospitals, orphanages, and (albeit rarer) juvenile correctional facilities, where the number of children to a single address can reach into the hundreds.

This automatically cuts the number of household deliveries required to around 3 million.

Secondly, the SLAI is equipped with eight niobium alloy chemical rocket engines (four under each wing).

Using ground-breaking research – later replicated here and here – Santa is able to catalyse his existing stockpile of carrots and mince pies from the preceding year into propellant and fuel, with the net effect that SLAI is capable of reaching speeds of up to 300,000 km/h.

Beginning at midnight Christmas Day in Western Samoa and the Pacific islands (10 am Christmas Eve Irish time), Santa Claus then conducts a longitudinal sweep of 10 sectors of the planet, returning to base in northern Finland after each foray.

He works east-to-west with each successive refuel, which has the effect of progressively shortening the round-trip time until he reaches the Central European time zone (after which it gets longer again).

This also allows him to take advantage of the earth’s 23 hourly time zones. With an itinerary that culminates at 5am in the Hawaiian islands, this gives Santa a total of 28 hours in which to deliver some 10 million presents.

This might seem like a lot, but the refueling round-trips (with distances of up to 30,000 km each) are actually the easy part.

What really keeps the clock ticking is the process of navigating between cities, and then delivering each present to the address of its new owner.

Operation Chimney

Source: Claude Paris/PA Images

For this, Santa uses a sophisticated GNSS (global navigation satellite system) codenamed Rudolph, and 15,000 unmanned aerial vehicles (UAVs, or drones), which are deployed from the SLAI in mid-flight.

Each drone is equipped with a blueprint for each household (to quickly locate entry points).

They are also loaded with gigapixel imaging technology which, roughly speaking, ensures that, in real time, their trajectory conforms to both an encoded global satellite map, and the metadata (name, address, coordinates) embedded in each present they’re carrying.

With an average of 360,000 presents being delivered every hour (volume varies depending on density of population), and a complement of 15,000 drones, this leaves each “Little Helper”, as they are known, performing the precision drop of 24 presents per hour, on average.

Factoring in the need to refuel and reload in the Arctic Circle (on average every two hours and 48 minutes), this leaves around 2-2.5 minutes for each UAV to locate and enter a household, securely deposit the present, and retrieve whatever foodstuffs have been left out (for later catalysis and conversion into fuel), before returning to the SLAI for redeployment.

Can Santa really deliver all the world’s presents in one night?

He can, and he does.

To keep up with Santa’s movements tonight, check out the official Santa Tracker, a (recently-declassified) project of NORAD, the North American Aerospace Defence Command.