54 Fun Facts About Time

Since 1967 the second has been defined by the radiation frequency of an atom of which element?

The definition counts 9,192,631,770 periods of caesium-133 radiation. Optical clocks based on strontium and aluminium ions are now more precise, so the definition may change again.

The name for the 60th division of a minute comes from the Latin pars minuta secunda, meaning what?

The minute was the pars minuta prima, the first small division of the hour into 60 parts; dividing again by 60 gave the second small part.

Leap seconds are added to Coordinated Universal Time to keep it in step with what?

Earth's rotation. It varies unpredictably, and the extra second added in June 2012 locked up servers at sites including Reddit.

Why is Coordinated Universal Time abbreviated UTC rather than CUT?

A compromise between English and French: English speakers would say CUT and French speakers TUC, so one code was chosen for every language.

In which city did the 1884 International Meridian Conference choose Greenwich as prime meridian?

Washington, D.C. France abstained from the vote, and Paris mean time stayed its legal time until a 1911 law.

Which country's Line Islands sit at UTC+14, the most advanced time zone on Earth?

Kiribati. Until the end of 1994 its eastern islands were a day behind its capital, so it moved the Date Line around itself to share one date.

Which country keeps its clocks 5 hours 45 minutes ahead of UTC?

Nepal. It kept India's UTC+5:30 until 1986, then pushed its clocks 15 minutes ahead.

Which country spans five geographical time zones yet officially observes just one, set to its capital?

China. In far-western Xinjiang, many people unofficially keep Xinjiang Time, two hours behind Beijing, so times often need clarifying.

Which company was the first to standardise its timetable on Greenwich Mean Time, in November 1840?

Before 'railway time', towns kept their own local mean time, and Bristol ran about ten minutes behind London. Britain did not legislate a single standard time until 1880.

In 1883, US railroads reset their clocks on a signal from the Allegheny Observatory in which city?

Pittsburgh. The observatory's director, Samuel Langley, helped fund it by selling time signals to railroads and cities.

Scottish-born engineer Sir Sandford Fleming proposed worldwide time zones in the 1870s while working in which country?

Canada. A timetable mix-up that made him miss a train reportedly helped inspire his search for a simpler way to keep time.

Strictly speaking, 'Big Ben' is the nickname of what?

The Great Bell. It kept ringing throughout the Blitz, even as bombs fell on London.

Clockmakers fine-tune the Great Clock of Westminster by adding or removing what from its pendulum?

Old pennies. Each coin lifts the pendulum's centre of mass so it swings faster, and one penny changes the clock's rate by 0.4 seconds a day.

In 2012 the Palace of Westminster's clock tower was officially renamed in honour of whom?

Queen Elizabeth II. MPs backed the change for her Diamond Jubilee; the palace's west tower already honoured Queen Victoria, the only earlier British monarch to reign 60 years.

Which foundry cast the giant hour bell for the Great Clock of Westminster in 1858?

Whitechapel. The bell cracked months after it first rang in 1859, and the foundry blamed a hammer over twice the specified weight.

Which scientist invented the pendulum clock in the 1650s?

Christiaan Huygens. He had clockmaker Salomon Coster build it, and its far better accuracy made pendulum clocks spread quickly across Europe.

The first quartz clock was described and built in October 1927 at which organisation?

Bell Labs. Quartz clocks went on to replace precision pendulum clocks as the standard timekeepers for science and industry.

Which company sold the world's first commercial quartz wristwatch, the Astron, in December 1969?

Seiko. Its launch began the quartz crisis, in which electronic watches drove Switzerland's mechanical watchmakers into steep decline.

Which physicist built the first practical atomic clock at Britain's National Physical Laboratory in 1955?

Louis Essen. A master of precise timekeeping, he was also a persistent critic of Einstein's relativity and rejected time dilation.

In 1971 Hafele and Keating tested relativity by flying four atomic clocks around the world aboard what?

Commercial airliners. As predicted, the clocks flown eastward lost time and those flown westward gained it, compared with clocks left on the ground.

Why will some computers that store Unix time in 32 bits fail in January 2038?

Their seconds counter runs out. Unix time counts seconds from 1970, and after 19 January 2038 a signed 32-bit count wraps round to 1901.

Which publication maintains the Doomsday Clock?

The clock first appeared on the June 1947 cover, drawn by artist Martyl Langsdorf, whose husband had worked on the Manhattan Project.

Which American envoy joked in 1784 that Parisians could save candles simply by getting up earlier?

Benjamin Franklin. His satirical letter proposed taxing window shutters and firing cannons at sunrise to wake the sluggards.

Swatch Internet Time, launched in 1998, divides the day into 1,000 equal units called what?

.beats. Swatch pitched it so internet users worldwide could share one time, with no time zones to juggle.

The base-60 counting system behind 60 minutes and 60 seconds originated with which ancient people?

The Sumerians. Nobody knows for sure why they chose 60, but it divides evenly by every number from 1 to 6, which makes fractions easy.

Which ancient civilisation divided the night into 12 parts, leading to our 24-hour day?

The Egyptians. Astronomers timed the dark by watching 12 stars appear in turn, so the hours stretched and shrank with the seasons.

The Greek word clepsydra, used for a clock driven by dripping liquid, literally means what?

Water thief. The name joins Greek words for 'steal' and 'water', and in Athenian courts one timed how long each speaker could talk.

Many churches once kept an hourglass in view to time what?

Sermons. After about 1500, smaller spring-driven clocks began pushing sandglasses out of everyday use.

Cuckoo clocks were popularised and exported to the world from which region of Germany?

The Black Forest. Yet the first known cuckoo clock, described in 1629, stood in a Dresden collection, before any clockmakers worked in the Black Forest.

The first telephone speaking clock service was launched on 14 February 1933 in which country?

France. The Paris Observatory built it because so many callers asked for the time that its only phone line was always busy.

What stopped the Times Square ball drop in the only two years it has been skipped since 1907?

Wartime blackouts. In 1942 and 1943 crowds gathered anyway, marking midnight with a minute of silence followed by chimes.

Since 1833, the red ball atop the Royal Observatory in Greenwich has normally dropped each day at what time?

1 p.m. Despite sitting at the home of Greenwich Mean Time, it follows British Summer Time in summer, so it then falls at noon GMT.

Which city's famous astronomical clock was first recorded in 1410?

Prague. Legend says its maker Hanuš was blinded so he could never build another, but he was not really its maker: the clock was already decades old in his time.

Which billionaire funded the 10,000-year Clock of the Long Now, being built inside a Texas mountain?

Jeff Bezos. The clock keeps ticking on its own, but its dials only catch up to the present moment when a visitor winds it.

Which cue does most to reset the body clock after flying across time zones?

Daylight. Timing matters, though: light at the wrong hour can push the body clock further off, so jet-lag plans set times to seek it and to avoid it.

The word circadian comes from Latin words meaning what?

About one day. Left to itself, the human body clock doesn't keep exactly 24 hours, so outside cues must reset it each day.

Hall, Rosbash and Young won the 2017 Nobel for uncovering the body-clock genes of which organism?

Fruit flies. In the 1970s, researchers had found flies whose mutations in one gene, which they named period, threw their daily rhythm off.

Louis Cartier made a 1904 wristwatch for Alberto Santos-Dumont so he could check the time while doing what?

Flying his airship. Men then carried pocket watches, but he needed both hands on the controls, so Cartier put a watch on a wrist strap.

Which planet takes longer to spin once on its axis than to travel once around the Sun?

Venus. It also spins backwards, so on its surface the Sun would rise in the west and set in the east.

John Harrison's marine timekeepers, such as his H4 watch, let sailors work out what?

Their longitude. After years of feuding with the Board of Longitude, Harrison finally won his reward from Parliament, with the King's backing.

Which Pacific nation deleted Friday 30 December 2011 to jump west of the Date Line?

Samoa. It was undoing an 1892 switch, when American traders persuaded its king to repeat the Fourth of July and join the American side.

Which Asian country ran a day behind its neighbours until 1844 because it was administered from Mexico?

The Philippines. To catch up, its governor simply deleted a day: Monday 30 December 1844 was followed directly by 1 January 1845.

Why did Alaska's calendar suddenly jump ahead in October 1867?

The US bought it from Russia. Alaska swapped Russia's old calendar for the American one and moved to the American side of the date line.

Which kind of clock took its everyday name from a hit 1876 song by Henry Clay Work?

Grandfather clock. In the song, the old man's tall clock stops for good the moment he dies.

The a.m. in clock times abbreviates the Latin ante meridiem, which means what?

Before midday. Strictly, noon is neither before nor after midday, which is why '12 a.m.' and '12 p.m.' so often cause confusion.

On 1 January 2000, the Y2K bug stopped what from working at Delaware's racetracks?

Slot machines. That same day, the US Naval Observatory, which runs the nation's master clock, showed the date on its website as 19100.

Stonehenge's main axis is aligned to the sunrise on which day of the year?

Summer solstice. Yet bones from nearby feasts suggest its builders may have gathered there mainly in midwinter.

The tiny unit of time at which today's theories of physics break down is named after which physicist?

Planck. Our best account of the Big Bang only begins once the universe was one Planck time old, about 5.4 × 10⁻⁴⁴ seconds.

On a sundial, what is the shadow-casting rod or plate called?

Its time-telling edge is the style. Cheap garden sundials often have the gnomon set at the wrong angle for their latitude, so they can never read correctly.

Su Song's astronomical clock tower of 1088 had the first known example of what?

An endless chain drive. When the capital Kaifeng was lost in 1127, the tower was taken apart and carried off, and nobody could ever put it back together.

In H. G. Wells's The Time Machine, which two races live in the year 802,701?

Eloi and Morlocks. The Eloi are terrified of the dark because the underground Morlocks come up at night to eat them.

Which pope introduced the 1582 calendar reform that replaced the Julian calendar?

Gregory XIII. To undo the drift that had built up, ten days were skipped, so the day after 4 October 1582 was 15 October.

In Hindu cosmology, a kalpa of 4.32 billion years is one day in the life of which god?

Brahma. His night lasts just as long, a time of dissolution before creation begins again with his next day.

Which 5th-century BC Greek argued that time, motion and change were illusions, inspiring Zeno's paradoxes?

Parmenides. To defend him, Zeno argued that a runner can never reach the finish, since she must first cover half the distance, then half of what remains, and so on forever.