funfacts.space
Interactive calculators that put the true scale of the universe in your hands. Numbers only — no fluff.
How large does an object appear in the sky? Enter any two of diameter, distance, or angular size — the calculator solves for the third.
How bright does an object appear? Calculates apparent magnitude for stars and planets, with comparison bars and a sky visualization.
How long does it take light to travel between any two solar system objects? Enter a distance or a time — the calculator solves for the other.
How much would you weigh on Jupiter? Enter your weight, toggle lbs or kg, and see your weight on every planet, moon, and the Sun.
Real atmospheric readings from NASA's InSight lander. Browse 7 Martian sols of temperature, wind, and pressure data — with Earth comparisons for context.
Decode the math behind any optics spec. Enter magnification and objective diameter to get exit pupil, light gathering, limiting magnitude, and field of view — plus reference tables for common sizes.
How fast do you need to go to break free from a planet's gravity? Escape velocities for every solar system body — with perspective on what these speeds really mean.
The Milky Way is roughly 13 billion years old and contains an estimated 100–400 billion stars. Even if only a tiny fraction host life, the galaxy should be teeming with civilizations — some millions of years ahead of us. So why is the universe silent? Enrico Fermi asked this over lunch in 1950, and we still don't have an answer.
Robin Hanson's Great Filter theory proposes that somewhere between dead chemistry and galaxy-spanning civilizations, there's a nearly impassable barrier. Either the filter lies behind us — meaning abiogenesis (life from non-life) is extraordinarily rare — or it lies ahead of us, waiting for every technological species. The latter is the terrifying possibility: the cosmos is quiet because something destroys advanced life before it can expand.
Perhaps advanced civilizations already know we're here — and have agreed not to interfere. Earth might be a protected reservation, observed from a distance while we develop naturally. It would explain the silence without requiring us to be alone. The disquieting implication: we may have been deemed not yet worthy of contact, or too fragile to survive the knowledge that we are not alone.