QUESTION 1 / 20 · SOLAR SYSTEMEasy
Which planet is known as the Red Planet?
LOOK-BACK EXPLORER
When did this light set off?
Light travels about 300,000 km every second. Pick an object to see how long its light has been travelling, and what was happening on Earth when it left.
1 second1 year1 million years13 billion years
LIGHT HAS BEEN TRAVELLING2.5 million years2.5 million light-years, the farthest thing most people can see unaided
MEANWHILE, ON EARTHEarly members of our genus, Homo, were making the first stone tools in Africa.
What this astronomy quiz covers, in short
Twenty multiple-choice questions, four in each of five topics: the solar system, stars, galaxies and the universe, space exploration, and observing the night sky.
Distances in the explorer are rounded; some, like Betelgeuse's, are still uncertain by a few hundred light-years. Moon counts change as new ones are found. The quiz is our own and not normed.
By What's Your IQ · Reviewed 4 Oct 2026- Format
- 20 multiple-choice questions, 4 options each
- Topics
- Solar system, stars, galaxies, exploration, night sky
- Bonus
- Look-back explorer, 7 objects
- Level
- Easy to medium, a few hard
1 galaxywas the whole universe, as far as most astronomers knew, until the 1920sThen Edwin Hubble used a method discovered by Henrietta Leavitt to show the Andromeda "nebula" was far outside the Milky Way.1,2
1912A cosmic yardstick.Henrietta Leavitt found that certain pulsating stars' brightness reveals their true distance.
1924Other galaxies.Hubble found one of those stars in Andromeda and showed it lay far beyond the Milky Way.
1929An expanding universe.Hubble showed that more distant galaxies are moving away faster, the first evidence for the Big Bang.
1965The Big Bang's afterglow.Penzias and Wilson detected faint microwave radiation from every direction, left over from the early universe.
- Leavitt, H. S., & Pickering, E. C. (1912). Periods of 25 variable stars in the Small Magellanic Cloud. Harvard College Observatory Circular, 173, 1–3.
- Hubble, E. (1929). A relation between distance and radial velocity among extra-galactic nebulae. PNAS, 15(3), 168–173.
- Penzias, A. A., & Wilson, R. W. (1965). A measurement of excess antenna temperature at 4080 Mc/s. The Astrophysical Journal, 142, 419–421.