James Webb Space Telescope
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48 free James Webb Space Telescope trivia questions with answers — science & nature quiz, new questions added Oct 2026.
The James Webb Space Telescope is the biggest telescope ever put in space, and for most of its life it looked like it might never get there. Conceived in 1996 as a $1 billion successor to Hubble, it launched on Christmas Day 2021 at ten times that price, unfolded 18 gold-coated mirrors and a five-layer sunshield a million miles from Earth, and then started returning pictures of galaxies that existed 290 million years after the Big Bang. These 48 questions cover the machine and its story. The beryllium mirror segments and their actuators, the Kapton sunshield with an SPF of a million, the halo orbit around L2, the four instruments and who built them, and the JavaScript dialect that runs it. Then the history: the 2002 renaming, the 2011 attempt to cancel it, the torn sunshield of 2018, the 344 single-point failures, the Ariane 5 launch, the first deep field and the record galaxy JADES-GS-z14-0. Easy questions stick to the mirror and the launch; the hard tier asks about HD 84406, the SIDECAR ASIC and who was called "the most effective leader of a mission" in NASA history. Every answer is cited to a page we checked, with a short explanation so you learn something either way.
30 of 48 questions with answers and explanations. Play the quiz
Q 01Webb was built to look far enough back in time to see what?
The first galaxies forming
The first galaxies forming. Their light set out over 13 billion years ago and has been stretched into the infrared on the way, which is why Webb was built as an infrared telescope.
Q 02Webb finally lifted off on which holiday in 2021?
Christmas Day
Christmas Day. Liftoff had been set for Christmas Eve until a poor weather forecast at the launch site pushed it back by 24 hours.
Q 03Which rocket carried Webb into space?
Ariane 5
Ariane 5. Europe supplied the launch at no charge, and in return its astronomers were guaranteed roughly 15 percent of Webb's observing time.
Q 04Where does Webb orbit?
Near the Sun–Earth L2 point
Near the Sun–Earth L2 point. From there the Sun, Earth and Moon always sit in the same part of the sky, so a single sunshield can block the heat of all three at once.
Q 05Webb was launched from a spaceport on South American soil belonging to which country?
France
France. The spaceport is in French Guiana, an overseas region about five degrees from the equator, where Earth's spin gives a departing rocket an extra push.
Q 06What metal are Webb's mirror segments made of?
Beryllium
Beryllium. It was chosen for being light, stiff and steady in shape in deep cold, which is why each 1.3-metre segment weighs only about 20 kilograms.
Q 07Webb's mirror dwarfs Hubble's; how does Webb's mass compare?
About half
About half. A mirror made like Hubble's and scaled up would have been too heavy to launch, so Webb's had to be about ten times lighter for its size.
Q 08Why must Webb's telescope be kept below about −223°C?
Its own glow would blind it
Its own glow would blind it. Anything warm shines in the infrared light Webb collects, so it has to be far colder than Hubble, which is kept at about room temperature.
Q 09What fills the gaps between Webb's five sunshield layers?
Nothing
Nothing. The vacuum between the layers is a very good insulator, and each layer runs cooler than the one below as its heat radiates out sideways through the gaps.
Q 10What sun protection factor does Webb's sunshield effectively have?
1,000,000
1,000,000. Its five layers cut more than 200 kilowatts of solar energy to a fraction of a watt by the time it reaches the telescope.
Q 11Webb's open sunshield is about the size of what?
A tennis court
A tennis court. The ground team unfolded and tightened it by remote command over eight days, finishing ten days after launch.
Q 12What limits Webb to about 40 percent of the sky at once?
Its need for shade
Its need for shade. Pointing too close to the Sun would let heat reach the cold mirror, but its window drifts as the months pass, so the whole sky comes into view every six months.
Q 13In 2022 Webb took the clearest picture of which planet's rings since Voyager 2 flew past in 1989?
Neptune
Neptune. Some of its faint rings had not been seen at all since that flyby, and the planet famous for its blue colour does not look blue to Webb's infrared camera.
Q 21Which Baltimore organisation runs Webb's day-to-day operations?
Space Telescope Science Institute
Space Telescope Science Institute. The centre that plans Hubble's observations also sent nearly every command that unfolded Webb, and Webb's data is still sent there for processing.
Q 22Who was James E. Webb, the man the telescope honours?
NASA's chief in the 1960s
NASA's chief in the 1960s. He was an attorney and manager, not a scientist or engineer, yet he ran the agency through the Apollo build-up and insisted it keep funding space science.
Q 23What was Webb called before it was renamed in 2002?
Q 14Why do bright stars in Webb's images show a distinctive pattern of long spikes?
Its hexagonal mirror segments
Its hexagonal mirror segments. Light bends at the segments' straight edges to draw six big spikes, and the struts holding the small second mirror add two fainter ones.
Q 15In 2022 Webb and Hubble both watched NASA deliberately crash which spacecraft into an asteroid?
DART
DART. It was the first time the two telescopes watched the same target at once, and the crash shortened the little moon's orbit by 32 minutes, proof that an asteroid can be nudged.
Q 16Webb spotted a watery plume more than 9,600 km long spraying from which moon of Saturn?
Enceladus
Enceladus. It gushes water fast enough to fill an Olympic swimming pool in a couple of hours, and Webb showed the plume feeding a doughnut-shaped cloud of water around Saturn.
Q 17What do the 248,000 tiny shutters in Webb's NIRSpec instrument let it do?
Study about 100 objects at once
Study about 100 objects at once. Each door is only a few hairs wide and opens on command, so one exposure can split the light of 100 chosen galaxies while the rest of the sky stays blocked.
Q 18Which part of Webb needs its own helium refrigerator to run far colder than the rest?
The Mid-Infrared Instrument
The Mid-Infrared Instrument. Longer wavelengths need colder detectors, so while the sunshield alone chills the others to around 40 kelvin, this one is pumped down below 7.
Q 19Besides NASA and the European Space Agency, which country is a full partner in Webb?
Canada
Canada. It built the sensor that keeps Webb locked on its targets and one of the four science instruments, which earned Canadian astronomers a guaranteed share of observing time.
Q 20Which company was Webb's prime contractor?
Northrop Grumman
Northrop Grumman. The contract went to TRW, which Northrop absorbed after a hostile takeover bid in 2002, so the telescope became Northrop's to build.
Next Generation Space Telescope
Next Generation Space Telescope. The working title marked it as the follow-up to Hubble, whose own planning name had been the Large Space Telescope.
Q 24Roughly how much had Webb cost by the time it launched in 2021?
$10 billion
$10 billion. When NASA formally committed to building it the estimate was about $5 billion for a 2014 launch, and under-funding in the early years let the delays snowball.
Q 25Webb was conceived under which 1990s NASA motto?
Faster, better, cheaper
Faster, better, cheaper. Administrator Dan Goldin's motto stood for small, quick missions, yet the telescope planned under it became the reverse: a single giant that took a quarter of a century to launch.
Q 26Webb's senior project scientist John Mather shared a Nobel Prize for measuring what?
The Big Bang's afterglow
The Big Bang's afterglow. His COBE satellite showed the faint microwave glow matched what a hot early universe should leave behind, and he then led Webb's science team from 1995 until 2023.
Q 27What went wrong with Webb in a 2018 practice deployment, helping to push back its launch?
The sunshield ripped
The sunshield ripped. Its tensioning cables also went slack, and NASA moved a launch planned for 2019 to no earlier than May 2020 to make time for repairs and more tests.
Q 28Which famous Hubble image of 1995 did Webb retake in 2022, revealing newborn stars inside the dust?
The Pillars of Creation
The Pillars of Creation. In Webb's near-infrared view the famous columns of gas and dust turn semi-transparent, so the newly formed stars inside them can be seen and counted.
Q 29In 2011 a US House committee voted to do what to Webb?
Cancel it
Cancel it. Astronomers reacted with dismay, and that November a compromise between the House and the Senate kept the telescope alive.
Q 30A 2010 Nature article described Webb as what?
The telescope that ate astronomy
The telescope that ate astronomy. The headline voiced a fear that Webb's swelling budget was swallowing the money for the other space-science missions NASA hoped to fly.