GPS Trivia
0Loading crowd target
0Loading crowd target
6correct to beat the crowd
49 free GPS trivia questions with answers — technology quiz, new questions added Sep 2026.
This GPS trivia quiz covers the satellite navigation system that went from a Cold War tool for missile submarines to the thing that finds your ride home. The easy questions cover what the letters stand for, who owns it, how many satellites make a full constellation, how many you need to fix a position and what your phone can do with it. From there the quiz moves through the story: the Johns Hopkins physicists who tracked Sputnik by its Doppler shift, Transit and Timation, the Labor Day 1973 meeting at the Pentagon, the first Block I launch in 1978, the Korean airliner that pushed Reagan to open the system to civilians and the 100-metre fuzz called Selective Availability. The hard end covers the engineering and the politics: the six orbital planes, the 20,200 km altitude and twelve-hour orbits, Einstein's 38 microseconds a day, Gladys West's Earth model, Schriever Space Force Base, the Gulf War jamming, the day in May 2000 accuracy jumped from 100 metres to five, the week-number rollover, GLONASS, Galileo and BeiDou, and the $5 billion price tag. Every answer was checked against the encyclopaedia entry for the Global Positioning System before publishing and the supporting sentence is stored with each question. Our space exploration, satellites and technology quizzes are natural next stops.
30 of 49 questions with answers and explanations. Play the quiz
Q 01What do the letters GPS stand for?
Global Positioning System
Global Positioning System, not 'Satellite': the satellites are only one of three parts, alongside the ground stations that steer them and the receiver in your hand.
Q 02Which treasure-hunting hobby was born in May 2000, days after civilian GPS signals suddenly became far more accurate?
Geocaching
Geocaching: on 3 May 2000 Dave Ulmer hid a bucket of trinkets in the woods of Oregon and posted its coordinates online. Within three days, two strangers had tracked it down.
Q 03Which branch of the US military operates the GPS satellites?
The Space Force
The Space Force, founded in 2019, took GPS over from the Air Force. US law obliges the Pentagon to keep the civilian signal on worldwide, free of any direct user fee.
Q 04What does every GPS satellite broadcast?
Its position and time
Its position and time: a receiver works out where it is from how long each signal took to arrive. Because receivers only listen and never transmit, any number of them can use GPS at once.
Q 05A GPS fix needs a fourth satellite to correct an error in the receiver's what?
Clock
Clock: the cheap clock in a phone drifts, and light covers about 300 metres in a millionth of a second, so a tiny timing slip would wreck the fix.
Q 06GPS satellites fly about 20,000 km up, in which class of orbit?
Medium Earth
Medium Earth orbit: at about 20,200 km, the satellites are spread over six orbital planes so that at least four are in view from virtually anywhere on the planet.
Q 07How long does one GPS satellite take to orbit the Earth?
About 12 hours
About 12 hours: two laps for every turn of the Earth means each satellite retraces the same track over the ground day after day.
Q 08GPS satellites also carry sensors that detect what?
Nuclear explosions
Nuclear explosions: every GPS satellite doubles as a lookout for the flash and radiation of a bomb going off anywhere on the globe, helping to police the treaties that ban nuclear tests.
Q 09Which company's rocket launched the first GPS III satellite in December 2018?
SpaceX
SpaceX: unusually, the Falcon 9 booster made no attempt to land afterwards. The Air Force wanted every drop of the rocket's performance spent on the satellite, leaving no fuel for the trip home.
Q 10GPS stations track which drift of a few centimetres a year?
Tectonic plates
Tectonic plates: by re-measuring the distance between fixed points, GPS tracks the plates directly. The Atlantic is widening by about 2.5 cm a year, roughly the speed at which fingernails grow.
Q 11The GPS III satellites carry nicknames such as Vespucci, Sacagawea and Amelia Earhart, honouring what kind of people?
Explorers
Explorers: the third satellite was to be Columbus, but before its 2020 launch it was renamed for Matthew Henson, the Black American who reported reaching the North Pole with Robert Peary in 1909.
Q 12What was the name given to the individual GPS satellites?
Navstar
Navstar: the name arrived in 1973, when a Labor Day weekend meeting at the Pentagon folded rival Navy and Air Force satellite projects into a single programme.
Q 13Which event showed two Johns Hopkins researchers that Doppler shifts could be used to navigate?
The launch of Sputnik 1
Q 21Which mathematician spent four decades at a US Navy base modelling the Earth's true shape, work that underpins GPS?
Gladys West
Gladys West: at Dahlgren in Virginia she programmed an early IBM supercomputer to map the planet's lumps and dips. She retired at 68, suffered a stroke, and went on to finish a PhD anyway.
Q 22A global map of GPS-tracked runs from the fitness app Strava was found in 2018 to reveal what?
Secret military bases
Secret military bases: soldiers jogging laps with fitness trackers had drawn glowing outlines of remote outposts in Afghanistan and Syria. An Australian student was the first to point it out.
Q 23In 2019 four pioneers of GPS shared the Queen Elizabeth Prize, a major international award in which field?
The launch of Sputnik 1: by timing the shift in its beeps, the pair could plot its orbit. Their director then flipped the trick: if you know where the satellite is, you can find out where you are.
Q 14In the 1970s the Navy's Timation satellites proved that which devices, vital to GPS, could survive and work in orbit?
Atomic clocks
Atomic clocks: a test satellite launched in 1974 carried the first into orbit. Clockmakers had to shrink a laboratory instrument and harden it for space without losing the stability that makes it useful.
Q 15The shooting down of which airliner in 1983 prompted President Reagan to promise GPS to civilians?
Korean Air Lines Flight 007
Korean Air Lines Flight 007: a navigation slip let the 747 stray into Soviet airspace, where a fighter shot it down and all 269 aboard died. Reagan wanted no airliner to get lost like that again.
Q 16What was the name of the policy that deliberately blurred civilian GPS fixes by about the length of a football field?
Selective Availability
Selective Availability: the satellites deliberately fudged their timing so that civilian fixes wandered by up to 100 metres, while military receivers held the key to strip the error out.
Q 17Which US president ordered the deliberate degradation of civilian GPS signals switched off?
Bill Clinton
Bill Clinton: the blurring stopped within hours of his announcement on 1 May 2000. The military had decided it could deny GPS to an enemy region by region instead of degrading it for the whole world.
Q 18In 2013 Texas students lured an $80 million yacht off course by attacking its GPS with a trick known as what?
Spoofing
Spoofing: unlike jamming, which merely drowns the real signal out, the fake signals set off no alarm. The ship turned and those aboard could feel it, yet the chart on the bridge still showed a straight line.
Q 19GPS fixes would drift by about 10 km a day if the satellites' clocks ignored which branch of physics?
Relativity
Relativity: speed slows the orbiting clocks, but weaker gravity up there quickens them by more. The net gain is 38 millionths of a second a day, so each clock is set to tick slightly slow before launch.
Q 20Which was the first war in which the US military widely used GPS?
The Gulf War of 1990-91
The Gulf War of 1990-91: GPS let coalition troops find their way across empty desert, but military receivers were so scarce that the Pentagon had to buy civilian sets to meet demand.
Engineering
Engineering: the prize rewards innovation of global benefit to humanity, and GPS qualifies handsomely, since billions of people with a smartphone now rely on it to find out where they are.
Q 24The GPS master control station sits at Schriever, a military base in which US state?
Colorado
Colorado: from Schriever, near Colorado Springs, an active-duty squadron and a reserve unit, together nicknamed Team Blackjack, fly the whole constellation day and night.
Q 25What is Russia's equivalent of GPS called?
GLONASS
GLONASS: begun by the Soviet Union, it decayed in the 1990s and was rebuilt to a full 24 satellites in 2011, because Moscow did not want to rely on an American system that could in theory be switched off.
Q 26What is the European Union's global navigation satellite system called?
Galileo
Galileo, after the Italian astronomer: unlike GPS it is under civilian control, and the chief reason for building it was independence, so that Europe need not rely on a system another power could switch off.
Q 27Which country completed BeiDou, its own global rival to GPS, with a final satellite launch in June 2020?
China
China: BeiDou is the Chinese name for the Big Dipper, the bright stars that travellers have long used to find north, which makes it a fitting name for a navigation system.
Q 28Under open sky, a typical smartphone's GPS fix is accurate to within about what distance?
5 metres
5 metres: when over a thousand online students in a hundred countries tested their own phones, the average came to 4.9 m.
Q 29In March 2025 a receiver built for NASA and Italy's space agency became the first to get a GPS fix where?
On the Moon
On the Moon: about 225,000 miles from home, a receiver on the Blue Ghost lander picked up navigation satellites built to serve Earth. NASA hopes future lunar crews can find their way the same way.
Q 30In April 2019, what made some older GPS devices reset their calendars by nearly 20 years?
A week counter hitting its limit
A week counter hitting its limit: GPS numbers its weeks with only ten binary digits, so after week 1,023 the count returns to zero. It happens every 19.6 years, and the press called this one a mini Y2K.