50 Fun Facts About Latitude and Longitude

Which coordinate specifies a point's north–south position on Earth?

It runs from −90° at the South Pole to 90° at the North Pole, with 0° at the Equator.

Lines of constant latitude are known as what?

They run east–west as circles parallel to the Equator; only the Equator itself is a great circle.

What are the imaginary pole-to-pole lines connecting points of equal longitude called?

The prime meridian defines 0° longitude; its anti-meridian is at 180°.

Which Greek letter is conventionally used for latitude in English texts?

Longitude gets lambda (λ); both are measured in degrees, minutes and seconds.

Which Greek letter usually denotes longitude?

Positive longitudes lie east of the prime meridian and negative ones west.

What is the latitude of the North Pole?

The South Pole is 90° S, written −90°.

How many degrees of longitude correspond to a one-hour difference in local solar time?

The Earth turns 360° in 24 hours, which is why longitude and time-keeping are so tightly linked.

Near which London landmark does the international reference meridian pass?

Greenwich was chosen by 41 delegates from 25 nations at the 1884 International Meridian Conference.

In which city was the 1884 International Meridian Conference held?

France argued for a neutral line, abstained, and kept using the Paris meridian until 1911.

Who established the position of the historic Greenwich meridian in 1851?

It was defined by his transit circle; today's GPS meridian runs about 102 metres to the east of it.

How far east of the Airy transit circle does the IERS Reference Meridian run at Greenwich?

The 5.3-arcsecond offset exists because Airy used astronomical longitude and the IERS uses a geodetic one.

Which navigation system uses the IERS Reference Meridian as its zero of longitude?

It is also the reference meridian of WGS 84 and the International Terrestrial Reference Frame.

Which country kept using the Paris meridian as its prime meridian until 1911?

In the 18th century most European states ran their prime meridian through their own capital.

Which ancient geographer first used a consistent prime meridian for a world map?

He ran it through the "Fortunate Isles" in the Atlantic so that every longitude would be positive.

Who is generally credited with inventing the geographic coordinate system?

He composed his now-lost Geography at the Library of Alexandria in the 3rd century BC.

Which Greek astronomer divided the Earth into 360° and ran his prime meridian through Alexandria?

He also proposed timing a lunar eclipse from two places to find their longitude difference.

What is the circumference of the Earth at the Equator, to the nearest thousand kilometres?

Precisely 40,075 km; the equatorial diameter is about 43 km greater than the polar one.

The Equator passes through the land of how many sovereign states?

Indonesia straddles the greatest length of it; the Maldives, Kiribati and the US touch it only at sea.

Which country straddles the greatest length of the Equator?

The highest point on the Equator is 4,690 m up the slopes of Volcán Cayambe in Ecuador.

The Equator is the only line of latitude that is also what?

Its plane passes through the centre of the globe; every other parallel is a smaller circle.

Why are sites near the Equator, such as Kourou, good spaceport locations?

The ground moves at about 460 m/s there, cutting the fuel needed for eastward launches.

The word "equator" comes from a medieval Latin phrase meaning what?

On the equinoxes, every latitude gets roughly a 12-hour day and 12-hour night.

At roughly what latitude does the Tropic of Cancer lie?

It marks the northernmost point where the Sun can be directly overhead, at the June solstice.

On which date is the Sun directly overhead at the Tropic of Capricorn?

It is the southernmost latitude where the Sun can be seen at the zenith.

In which zodiac constellation does the Sun actually appear at the June solstice in the 21st century?

Precession has shifted it since the Tropic of Cancer was named; at the December solstice the Sun is in Sagittarius.

The Tropic of Cancer is the southern limit of which alliance's mutual-defence obligation?

Members are not obliged to defend territory south of that line.

At roughly what latitude is the Arctic Circle?

South of it the Sun never stays up or down for a full 24 hours.

At about what rate is the Arctic Circle drifting towards the North Pole in the 21st century?

It tracks the Earth's axial tilt, which swings by about 2° over a 41,000-year cycle.

What does the word "arctic" mean in its original Greek?

Arktos is the bear, for the constellations Ursa Major and Minor in the northern sky.

The latitude of the polar circles equals what, in terms of Earth's axial tilt i?

The tropics sit at latitude i itself, currently about 23.44°.

Roughly how long is one degree of latitude on the Earth's surface?

That is about 69 statute miles or 60 nautical miles.

Which 1714 Act of Parliament offered rewards for finding a ship's east–west position?

It paid up to £20,000 for a method accurate to half a degree, administered by the Board of Longitude.

Which self-taught Yorkshire clockmaker built the marine chronometers that won the longitude prize?

He built five over three decades and fought Parliament for his money until 1773.

What was the top reward on offer under the 1714 Longitude Act?

Harrison submitted his watch-sized H4 for it in 1761.

What did Harrison's prize-winning H4 chronometer resemble?

It was about five inches across, far smaller than his earlier sea clocks H1 to H3.

Which Astronomer Royal turned Tobias Mayer's lunar tables into a nautical almanac?

Lunar distances rivalled chronometers until cheaper clocks made them obsolete after about 1850.

Whose discovery of Jupiter's four largest moons in 1610 offered a celestial clock for longitude?

Cassini's 1668 tables of the moons let the French re-survey their own coastline — and shrink the map.

Who patented the pendulum clock in 1657?

It was about 30 times more accurate than earlier clocks but useless in an ocean swell.

Which explorer twice tried to find his longitude from lunar eclipses, erring by up to 38°?

The attempts were made at Saona Island and in Jamaica.

From which landmark did wireless time signals for ships begin broadcasting in 1910?

Halifax, Nova Scotia had started in 1907; the signals let navigators reset their chronometers at sea.

The International Date Line roughly follows which meridian?

It zigzags around territories, but is a cartographic convention rather than international law.

Crossing the date line eastbound does what to the calendar date?

Westbound travellers jump forward a day.

Which island nation's Line Islands have the latest time zone on Earth, UTC+14?

The date line swings almost to 150° W to keep the whole country on one date.

Which country deleted Friday 30 December 2011 from its calendar by jumping across the date line?

It moved to the western side to line up its working week with Australia and New Zealand.

Which colony ran a day behind its Asian neighbours for 323 years until 1844?

As part of New Spain it kept Acapulco's side of the date line until its trade turned to China.

The IDL passes between the Diomede Islands in which body of water?

The line runs just 1.5 km from each island, so Big and Little Diomede sit on different dates.

What is the nickname for the point at 0° latitude, 0° longitude?

It is open Atlantic in the Gulf of Guinea, used by mapping software to flag bad 0,0 coordinates.

Which planet's prime meridian is fixed to a physical feature, the crater Airy-0?

It was set in 1971; Earth's is astronomically arbitrary.

Which method determines latitude in celestial navigation?

Measure the Sun's height at local noon, correct for declination, and you have your latitude.

The grid formed by lines of latitude and longitude together is called what?

On a Mercator map the parallels are horizontal and the meridians vertical; on other projections both curve.