What If?
Thought experiments about planets built a little differently. Change one thing about Earth and follow the consequences.
What If Earth Had Rings?
Imagine Saturn-style rings circling Earth. How they would look from different latitudes, how they would change our climate, and why they would make spaceflight much harder.
What ifWhat If Earth Had Two Suns?
Planets with two suns are real. How orbits work around a pair of stars, what double sunsets and double shadows would be like, and whether such worlds can be habitable.
What ifWhat If the Moon Disappeared?
No more moonlight, smaller tides, and a planet whose tilt could wander over millions of years. What Earth would be like without its Moon — and what the Moon has already done for us.
What ifWhat If Earth Were Twice as Big?
A planet with twice Earth's diameter would be a super-Earth with stronger gravity, a heavier atmosphere and very different conditions for life — and for anyone trying to launch a rocket.
What ifWhat If Earth Stopped Spinning?
A sudden stop would be catastrophic. A slow stop would give us six months of daylight, six months of night, and oceans that drain toward the poles. Here is what would happen.