Mars: The Red Planet – answers and explanations
Here are the answers to all 15 questions in the Mars: The Red Planet quiz, each with a short explanation. From Olympus Mons to Perseverance – how well do you know our rusty neighbour? Haven't played yet? Take the quiz first and compare your score.
Play the quiz · 15 questions1. What substance in Martian soil gives the planet its famous reddish colour?
Answer: Iron oxide, better known as rust
Mars looks red because its dust is rich in iron oxide, essentially rust. A 2025 Nature Communications study indicated the main iron oxide is ferrihydrite, a water-bearing form, hinting the planet rusted while liquid water was still present.
2. Olympus Mons on Mars holds what record in our solar system?
Answer: Tallest volcano
Olympus Mons is the tallest and largest volcano known in the solar system, a shield volcano rising about 22 km above the surrounding plains and roughly 600 km wide. Mariner 9 revealed its true nature in 1971-72.
3. What are the names of the two small moons orbiting Mars?
Answer: Phobos and Deimos
Mars has two tiny moons, Phobos and Deimos, discovered by Asaph Hall in 1877 and named after the Greek personifications of fear and dread, companions of the war god Ares.
4. Which NASA craft became the first to achieve powered flight on another planet?
Answer: The Ingenuity helicopter
NASA's Ingenuity helicopter made the first powered, controlled flight on another planet on April 19, 2021, hovering about 3 metres above Jezero Crater for roughly 39 seconds; it went on to complete 72 flights before its final one in January 2024.
5. Who wrote the novel 'The Martian', later filmed with Matt Damon?
Answer: Andy Weir
Andy Weir wrote The Martian, self-published in 2011 before a 2014 print edition, and Ridley Scott's 2015 film adaptation starred Matt Damon as stranded astronaut Mark Watney.
6. The huge canyon Valles Marineris is named after which NASA spacecraft?
Answer: Mariner 9
Valles Marineris, Latin for 'Mariner Valleys', honours NASA's Mariner 9, which discovered the canyon system while orbiting Mars in 1971-72. Stretching over 4,000 km near the equator, it is the largest known canyon system in the solar system.
7. How long is a Martian day, known as a sol?
Answer: About 24 hours and 39 minutes
A Martian solar day, called a sol, lasts 24 hours, 39 minutes and 35 seconds, about 2.7 percent longer than an Earth day. Mission teams run rover operations on sol time, so their schedules drift roughly 40 minutes later each day relative to Earth clocks.
8. Which mission sent back the first photos from the surface of Mars in 1976?
Answer: Viking 1
NASA's Viking 1 lander touched down in Chryse Planitia on 20 July 1976 and minutes later returned the first photograph ever taken from the Martian surface, an image showing one of its own footpads.
9. Mars is the Roman god of war. Who is his Greek counterpart?
Answer: Ares
The Roman war god Mars corresponds to the Greek god Ares, whose name also lives on in Martian terms such as areology and the moons Phobos and Deimos, named after Ares' sons.
10. Which astronomer's maps of Martian 'canali' sparked the famous canals myth?
Answer: Giovanni Schiaparelli
Italian astronomer Giovanni Schiaparelli mapped fine lines on Mars during the 1877 opposition from Milan's Brera Observatory and called them 'canali', meaning channels; the mistranslation as 'canals' fed Percival Lowell's theory of Martian irrigation works.
11. How long does Mars take to complete one orbit around the Sun?
Answer: About 687 Earth days
Mars completes one orbit of the Sun in about 687 Earth days (roughly 1.88 Earth years, or 668.6 sols), orbiting at an average distance of about 228 million km, 1.5 times Earth's distance from the Sun.
12. Compared with Earth, how wide is Mars?
Answer: About half Earth's diameter
Mars has a radius of about 3,390 km against Earth's roughly 6,371 km, so it is roughly half Earth's width, about 53 percent. Its smaller size also means surface gravity is only about 38 percent of Earth's.
13. Which NASA rover touched down in Jezero Crater in February 2021?
Answer: Perseverance
NASA's Perseverance rover landed in Jezero Crater on 18 February 2021, at a spot named Octavia E. Butler Landing. Jezero was chosen because it holds an ancient river delta where signs of past microbial life might be preserved.
14. Which H.G. Wells novel describes Martians invading Earth in war machines?
Answer: The War of the Worlds
H. G. Wells's The War of the Worlds, published as a book in 1898 after magazine serialisation in 1897, depicts Martians landing in Surrey and attacking in three-legged fighting machines armed with heat-rays.
15. The Martian moon Phobos takes its name from a Greek word meaning what?
Answer: Fear
Phobos comes from the Greek word for fear or panic, the name of a son of Ares who personified fear; its companion Deimos means dread or terror. Asaph Hall discovered both moons in August 1877.