Space & the Cosmos
Things you can never take apart, running on physics you can only watch.
- How a Rocket Engine Works — Burning the fuel is the easy part. The hard part is shoving three hundred kilos of propellant a second into a chamber already at ninety-seven atmospheres — which is why most of this engine is a pump, driven by a second, smaller rocket engine bolted to its side.
- How a Solar Eclipse Works — The Moon is 400 times smaller than the Sun and 400 times closer, so it fits over the disc almost exactly. Its shadow is a cone that tapers to a point right about where Earth is. On an average day it stops a few thousand kilometres short.
- How Gravity Works — An accelerometer in free fall reads exactly zero, and it is not broken. Nothing is pulling a falling thing down — what you feel as your weight is the floor shoving you off the path you would otherwise take.
- How the Seasons Work — Earth is closest to the Sun in early January, in the middle of northern winter. The seasons come from a 23.4° lean that tips each half of the planet toward the Sun and then away, and the same lean steers the monsoon rains and the snow line.
- How the Solar System Works — Eight planets falling around a star, and never landing. Every orbit is an ellipse with the Sun off to one side — and the Sun is not standing still either: it circles a point just outside its own surface while the whole system flies through the galaxy at 230 km a second.
- What Is a Black Hole? — The dark circle is not the hole — it is 2.6 times wider than the hole, because the hole bends the paths of the light behind it. Everything you can see of a black hole is the last thing that got away.