🚀 Stars, Galaxies & Cosmology Trivia Questions & Answers
The Milky Way, distant galaxies and the shape of the universe. Below are 30 free stars, galaxies & cosmology trivia questions with answers — part of Space trivia on BUZZ. Want a real challenge that adapts to what you know? Play the Space quiz — no signup needed to start.
30 Stars, Galaxies & Cosmology trivia questions
Q1. Our Milky Way has curvy arms winding out from its center, which makes it what kind of galaxy?
Answer: A spiral galaxy
💡 Spiral galaxies are rich in gas and dust, which is exactly the raw material new stars need to form in their arms.
Q2. What's the name of the supermassive black hole lurking at the center of our own Milky Way?
Answer: Sagittarius A*
💡 It weighs in at about 4.3 million times the mass of our Sun — modest by supermassive black hole standards.
Q3. What does a Sun-like star become when it runs out of core hydrogen and its outer layers puff up?
Answer: A red giant
💡 Even though its surface cools and reddens, a red giant's core actually burns hotter than ever, fusing helium into heavier elements.
Q4. Which star outshines every other star in Earth's night sky?
Answer: Sirius
💡 Sirius dazzles partly because it's a close neighbor, just 8.6 light-years from Earth.
Q5. About how long does light from the Sun take to reach Earth?
Answer: 8 minutes
💡 That means whenever you glance at the Sun, you're seeing it exactly as it looked about 8 minutes ago.
Q6. What is the closest star to Earth (excluding the Sun)?
Answer: Proxima Centauri
💡 Proxima Centauri is 4.24 light-years away — roughly 40 trillion km. It's a red dwarf star and part of the Alpha Centauri triple star system. Proxima Centauri b, a potentially habitable exoplanet, orbits it.
Q7. What does a light-year measure?
Answer: Distance light travels in a year
💡 A light-year is ~9.46 trillion km. Sunlight takes ~8 minutes to reach Earth; light from Proxima Centauri takes 4.24 years; Andromeda's light left 2.5 million years ago.
Q8. What is the Sun mainly made of?
Answer: Hydrogen and helium
💡 The Sun is about 74% hydrogen and 24% helium. It converts ~600 million tonnes of hydrogen to helium every second via nuclear fusion, with enough fuel for another ~5 billion years.
Q9. What is the Milky Way?
Answer: The galaxy containing our Solar System
💡 The Milky Way is a barred spiral about 100,000 light-years across with 100–400 billion stars. Our Solar System sits ~26,000 light-years from its centre and orbits it every ~225 million years.
Q10. What does the Big Bang theory describe?
Answer: The universe expanding from a hot, dense early state
💡 'Big Bang' began as Fred Hoyle's dismissive label; he backed the Steady State theory. The 1964 discovery of cosmic microwave background radiation confirmed the model. The universe is ~13.8 billion years old.
Q11. What is an 'exoplanet'?
Answer: A planet orbiting a star other than our Sun
💡 Over 5,600 exoplanets have been confirmed. NASA's Kepler mission (2009–2018) found over 2,600 alone. The 'habitable zone' (Goldilocks zone) is the orbital range where liquid water could exist on a planet's surface.
Q12. What will happen to the Sun in about 5 billion years?
Answer: It will expand into a red giant, then leave a white dwarf
💡 The Sun isn't massive enough to go supernova. As a red giant it will engulf the inner planets, then shed its outer layers, leaving an Earth-sized white dwarf that cools over trillions of years.
Q13. What is the Andromeda Galaxy, and what is its fate?
Answer: The nearest major galaxy (~2.5 million light-years away), on a collision course with the Milky Way in ~4.5 billion years
💡 Andromeda and the Milky Way will merge in a slow process taking hundreds of millions of years. Despite containing hundreds of billions of stars each, actual star collisions will be extremely rare — space is mostly empty.
Q14. What is the 'habitable zone' (Goldilocks zone) around a star?
Answer: The orbital range where liquid water could exist on a planet
💡 Not too hot, not too cold. Earth sits comfortably in the Sun's zone; Mars is at the outer edge, Venus just inside the inner edge. Red dwarfs have very close-in habitable zones.
Q15. What does E=mc² mean?
Answer: Energy equals mass times the speed of light squared
💡 It shows mass and energy are interchangeable. One kilogram of mass, fully converted, releases ~89 petajoules — about 21 megatons of TNT.
Q16. What is 'dark energy'?
Answer: Energy thought to accelerate the universe's expansion
💡 Dark energy makes up ~68% of the universe. It was inferred in 1998 from dim distant supernovae; Perlmutter, Schmidt, and Riess won the 2011 Nobel Prize.
Q17. What is the 'cosmic microwave background' (CMB)?
Answer: The thermal radiation left over from the Big Bang
💡 A near-uniform microwave glow filling all space at ~2.725 K. Penzias and Wilson found it accidentally in 1964, first suspecting pigeon droppings in their antenna.
Q18. What does the term 'observable universe' refer to?
Answer: The region visible from Earth, limited by light travel time
💡 The observable universe is ~46 billion light-years in radius (not 13.8 billion) because space expanded as light travelled. The actual universe may be vastly larger, or infinite.
Q19. What does the 'multiverse' theory propose?
Answer: Our universe is one of potentially infinite universes
💡 The multiverse is speculative but emerges from eternal inflation, the many-worlds interpretation of quantum mechanics, and string theory's landscape. It is not currently testable.
Q20. What is the 'Drake Equation'?
Answer: A probabilistic formula estimating the number of alien civilisations in the Milky Way
💡 Frank Drake formulated his equation in 1961 for the first SETI conference. Estimates range from fewer than 1 to millions of civilisations. The 'Fermi Paradox' asks: if civilisations are common, why haven't we heard from them?
Q21. What is the 'Fermi Paradox'?
Answer: The contradiction between the high probability of extraterrestrial civilisations existing and the lack of evidence or contact
💡 Enrico Fermi asked at lunch in 1950: 'Where is everybody?' Proposed solutions include the Great Filter (extinction before contact), the Zoo Hypothesis (they're watching us), and the rare Earth hypothesis (intelligent life is extraordinarily rare).
Q22. What did the Apollo missions bring back from the Moon?
Answer: 382 kg of lunar rock and soil from 6 missions (1969–72)
💡 Apollo moon rocks have revealed the Moon's age (~4.5 billion years) and confirmed it formed when a Mars-sized body collided with the early Earth. Lunar samples from all 6 missions are still being studied. NASA preserved portions unopened for 50 years for future technology.
Q23. What is the 'Big Crunch' theory?
Answer: A hypothetical scenario where the universe stops expanding, reverses, and collapses back on itself
💡 The Big Crunch was once the favoured model for the universe's end. The 1998 discovery that expansion is accelerating (dark energy) made it less likely. Current models favour the 'Big Freeze' (heat death) or 'Big Rip' (accelerating expansion tears matter apart).
Q24. What are smooth, football-shaped galaxies with barely any gas left for new stars called?
Answer: Elliptical galaxies
💡 Astronomers think many elliptical galaxies formed from head-on collisions between spiral galaxies.
Q25. Unlike Hubble, which mainly sees visible light, James Webb specializes in what kind of light?
Answer: Infrared light
💡 Infrared light slips through dust clouds more easily, letting Webb peek inside nebulae at baby stars forming.
Q26. Of two equally bright stars, one blue-white and one deep red, which is hotter?
Answer: The blue-white one
💡 The hottest stars, over 30,000 Kelvin, shine blue, while the coolest, near 3,000 Kelvin, glow a deep red.
Q27. Roughly half the Milky Way's stars travel with a companion star as what kind of system?
Answer: A binary star system
💡 Some studies put the multi-star share even higher, especially among the most massive stars.
Q28. Most of the faint light coming off a brown dwarf is just what, lingering since its formation?
Answer: Leftover heat, radiated as infrared
💡 A brown dwarf never gained enough mass for nuclear fusion to switch on, so it never truly became a star.
Q29. In 2019, which prize did Mayor and Queloz win for finding a planet circling a Sun-like star?
Answer: Nobel Prize in Physics
💡 They split the prize with cosmologist James Peebles, honored the same year for unraveling the universe's large-scale structure.
Q30. How many roughly Earth-sized planets does the star TRAPPIST-1 have circling it?
Answer: Seven
💡 Three of TRAPPIST-1's seven worlds sit in the habitable zone, the just-right distance where liquid water could survive.
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