Science
How Well Do You Really Know the Sun?
It's just a ball of fire, right? Wrong. The Sun is way weirder than you think.
It's just a ball of fire, right? Wrong. The Sun is way weirder than you think.
The Sun contains 99.86% of all the mass in our solar system, yet most people know surprisingly little about the star that makes life on Earth possible. This quiz draws from a pool of 50 questions covering solar structure, sunspots, eclipses, nuclear fusion, and the Sun's eventual fate — with each attempt randomized so no two rounds are the same.
Each round presents 10 multiple-choice questions. Pick your answer, get instant feedback with a detailed explanation, and see your final score at the end. No signup or timer — just you and the Sun.
Questions span everything from the nuclear fusion reactions powering the Sun's core to the 11-year sunspot cycle that affects space weather here on Earth. You'll explore why the corona is mysteriously hotter than the surface, how the Carrington Event of 1859 demonstrated the power of solar storms, and what will happen when our star exhausts its hydrogen fuel billions of years from now.
The Sun is composed primarily of hydrogen (about 73%) and helium (about 25%), with trace amounts of heavier elements like oxygen, carbon, neon, and iron. In its core, nuclear fusion converts hydrogen into helium at a rate of about 600 million tons per second, releasing the energy that powers the Sun.
The Sun is approximately 4.6 billion years old. It formed from a collapsing cloud of gas and dust — a solar nebula — and is currently about halfway through its main-sequence life. It has enough hydrogen fuel to continue shining for roughly another 5 billion years before it begins to evolve into a red giant.
In about 5 billion years, the Sun will exhaust its hydrogen fuel and expand into a red giant, engulfing Mercury, Venus, and possibly Earth. After shedding its outer layers as a planetary nebula, the remaining core will collapse into a white dwarf — a dense, slowly cooling stellar remnant. The Sun is not massive enough to explode as a supernova.
Last updated: March 2026