The quiz master is away, but the moment has been prepared for. Secret blueprints hidden in an air-conditioning unit within the Guardian’s London offices have been discovered that outline 15 somewhat less topical questions than usual, as they had to be set out in advance. There are no prizes. It is just for fun. Let us know how you get on in the comments. The Thursday quiz, No 70 1.HAPPY BIRTHDAY: It is Rachel Bilson"s birthday today. Happy birthday, Rachel! But what was the name of her character in The OC? Marissa Cooper Summer Roberts Zoe Hart Kaitlin Cooper Reveal 2.SECRETS OF THE STARS: Which of these stars is the brightest member of the constellation of Taurus? Electra Merope Aldebaran Ron Reveal 3.TAMMY"S TEASER: Tammy Wynette had a hit single with D-I-V-O-R-C-E in 1968. But which I is a country with a population of around 40 million people? Italy Indonesia Iraq Iran Reveal 4.I"M AFRAID I CAN"T DO THAT, DAVE: On 25 August 1991, Linus Torvalds announced the first version of what would become which computer operating system? Linux LDAP NewDos Wotan Reveal 5.1966 AND ALL THAT: A series of questions not about football leading up to the 2022 World Cup. The 1966 Fifa World Cup was held in England. But who was British prime minister in 1966? Sir Alec Douglas-Home Harold Macmillan Harold Wilson Edward Heath Reveal 6.WHY THE LONG FACE? What was the name of the pantomime horse (not pictured) that used to appear in British children"s TV show Rentaghost? Mr Twinkle David Myrka Dobbin Reveal 7.THE VINYL COUNTDOWN: What does the RCA stand for in the name of the famous record label? Radio Corporation of America Radiogram Company of America Recording Company of America Radiophonic Corporation of America Reveal 8.GCSE SCIENCE CORNER: Which of these provide the human heart muscle with the glucose and oxygen it needs to operate? Pulmonary artery The coronary arteries Hepatic vein Aorta Reveal 9.GCSE SCIENCE BUT IN THE 1600s: Who (not pictured), on this day in 1609, demonstrated his first telescope (not pictured) to Venetian lawmakers? Leonardo da Vinci Galileo Galilei Nicolaus Copernicus Tycho Brahe Reveal 10.MYSTERIOUS THINGS: Where would you find a Stockbridge damper? At a horse show In a pendulum-driven grandfather clock In the propulsion mechanism of a submarine On an electricity pylon or transmission tower Reveal 11.MYSTERIOUS THINGS (SLIGHT RETURN): Who wrote the horror novel The Fog, published in 1975 James Herbert John Carpenter Stephen King J R Hartley Reveal 12.OFF WITH THEIR HEADS: Today marks the anniversary of the death of French king Louis IX (not pictured) in 1270. How many kings named Louis did the French monarchy eventually get up to by the time of the last one, who died on 16 September 1824? Louis XVI (16th) Louis XVIII (18th) Louis XX (20th) Louis XXI (21st) Reveal 13.MUSIC: The band Wet Leg were the breakout cult 6Music success of 2021. But which island did Hester Chambers and Rhian Teasdale grow up on? Isle of Sheppey Isle of Man Isle of Mull Isle of Wight Reveal 14.COUNTRIES IN DISGUISE: The territory that used to be the Kingdom of Lombardy is now mostly in which modern European country? Germany France Spain Italy Reveal 15.COMMONWEALTH GAMES: The 22nd Commonwealth Games took place in Birmingham earlier this month. How many countries are members of the Commonwealth, according to its own website? 36 – which is both the square of six and a triangular number, making it a square triangular number. 44 – the same number of years between Kate Bush"s two UK No 1 singles. 56 – the number of years between England"s men winning the World Cup in 1966 (see question 5) and England"s women winning the Euros. 66 – like the route that winds from Chicago to LA in the song