50 free James Webb Space Telescope trivia questions with answers — science & nature quiz, new questions added Aug 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 50 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 50 questions with answers and explanations. Play the quiz
Q 01In which part of the spectrum does Webb mainly observe?
Infrared
Its range runs from long-wavelength visible red through the mid-infrared, 0.6 to 28.5 micrometres.
Q 02On what date was Webb launched?
25 December 2021
It lifted off on an Ariane 5 from Kourou, French Guiana, in a launch Space.com called "flawless".
Q 03Which rocket carried Webb into space?
Ariane 5
The European launcher was part of ESA's contribution to the partnership.
Q 04Where does Webb orbit?
Near the Sun–Earth L2 point
L2 is about 1.5 million km from Earth; Hubble, by contrast, circles just 550 km up.
Q 05Roughly how far from Earth is the L2 point where Webb sits?
1.5 million km
That is about four times farther out than the Moon.
Q 06How many hexagonal segments make up Webb's primary mirror?
18
Together they form a 6.5-metre mirror, against Hubble's single 2.4-metre disc.
Q 07What metal are Webb's mirror segments made of?
Beryllium
Beryllium is light, very stiff and holds its shape at cryogenic temperatures; the gold coat reflects infrared.
Q 08What is the diameter of Webb's primary mirror?
6.5 metres
It collects about six times as much light as Hubble.
Q 09Below what temperature must Webb be kept so its own heat does not blind it?
50 K
Otherwise the telescope's own heat glow would swamp the faint light it is collecting.
Q 10How many layers does Webb's sunshield have?
Five
Each is Kapton E film about 0.1 mm thick, coated with aluminium on both sides.
Q 11What sun protection factor does the sunshield effectively have?
1,000,000
Suntan lotion manages 8 to 50.
Q 12How many times was the sunshield folded to fit inside the rocket fairing?
Twelve
Fully open it measures about 14 by 21 metres, roughly a tennis court.
Q 13How much of the sky can Webb see from any one position?
40 percent
Over six months, as it moves around the Sun, it can reach the whole sky.
Q 14How many small actuator motors position and adjust Webb's optics?
Q 21Which company was Webb's prime contractor?
Northrop Grumman
It inherited the contract when it bought TRW in a hostile bid in 2003; Ball built the telescope optics.
Q 22Which Baltimore organisation runs Webb's day-to-day operations?
Space Telescope Science Institute
STScI in Baltimore also runs Hubble and sits on Johns Hopkins' Homewood campus.
Q 23James E. Webb ran NASA during which years?
1961 to 1968
He oversaw Mercury, Gemini and most of Apollo; the telescope took his name in 2002.
132
They can place the mirror segments to an accuracy of 10 nanometres.
Q 15Why do bright stars in Webb images show six diffraction spikes?
Its hexagonal mirror segments
Two fainter spikes appear too; Hubble's four-spike pattern comes from its support struts.
Q 16What kind of optical design does Webb use?
Three-mirror anastigmat
Curved secondary and tertiary mirrors give aberration-free images across a wide field.
Q 17Which Webb instrument also serves as the wavefront sensor that aligns the mirror?
NIRCam
It was built by a team led by the University of Arizona under Marcia Rieke.
Q 18Who built the NIRSpec spectrograph?
The European Space Agency
Its microshutter array lets it take spectra of hundreds of objects at once.
Q 19Which instrument must be kept below 6 K by a helium cryocooler?
MIRI
The Mid-Infrared Instrument covers 5 to 27 micrometres and is led by George Rieke and Gillian Wright.
Q 20Which country's space agency supplied the Fine Guidance Sensor and NIRISS?
Canada
NIRISS was led by René Doyon at the Université de Montréal.
Q 24What was the project called before it was renamed in 2002?
Next Generation Space Telescope
NASA administrator Sean O'Keefe made the change to honour his Apollo-era predecessor.
Q 25What was the original budget estimate for Webb in 1999?
US$1 billion
The final bill came to about US$10 billion, and the planned 2007 launch slipped 14 years.
Q 26Which NASA administrator coined "faster, better, cheaper" and pushed segmented mirrors?
Dan Goldin
Breaking the single-mirror barrier meant learning to live with moving parts.
Q 27Who was Webb's project scientist at Goddard during development?
John C. Mather
Mather shared the 2006 Nobel Prize in Physics for COBE's measurements of the cosmic microwave background.
Q 28What happened in a 2018 practice deployment that delayed the launch by two years?
The sunshield ripped
An independent review then counted 344 single-point failures that all had to go right.
Q 29How many potential single-point failures did the review identify in Webb's launch and deployment?
344
Each was a step with no backup; every one had to succeed for the telescope to work.
Q 30In which year did a House committee move to cancel the Webb project?
2011
Congress reversed course in November and capped the remaining budget at US$8 billion.