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Journeys

晴れた午後から初期宇宙まで、「なぜ」の連鎖をたどる · 短く出典付きの答えが続く、穏やかな分岐の道

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The sun is shining today. Why is it daytime where you are right now?

It is daytime because the part of Earth you are standing on is currently turned toward the Sun. Earth is a spinning ball: it rotates once on its axis about every 24 hours. The half facing the Sun is lit, and we call that day; the half turned away sits in Earth’s own shadow, and we call that night.

The Sun does not really travel across your sky. It looks like it rises and sets, but that motion is the ground beneath you turning. Sunrise is the moment your horizon rotates into the sunlight; sunset is the moment it turns back out of it.

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About Journeys

Journeys is a calm, branching way to be curious. Instead of a quiz, you follow a chain of "why?" from an everyday fact toward deeper causes. The first journey, But Why Though?, opens on a simple thought · "the sun is shining today" · and lets you ask why, read a short sourced answer, and choose which question to follow next.

You steer, and you can linger. There are no timers, no streaks, and no forced answers. Every node gives you a precise question, one to three short paragraphs of answer, and the sources behind it, then offers one or more follow-up questions. Some steps branch: from a sunny afternoon you can head into the Earth beneath your feet (why night falls, why the sky is blue, why there are seasons) or out toward the Sun itself (why it shines, why it fuses hydrogen, and how the universe came to be mostly hydrogen at all).

Honest about what we know. Each answer is backed by an authoritative reference you can check · NASA, OpenStax, and Encyclopaedia Britannica. Where science is settled, the journey says so; where it reaches an open question, such as what caused the Big Bang, it says that too rather than pretending to certainty. A small path map shows where you have been and where your next choices lead, without spoiling the parts you have not explored.

Part of the PlayMemorize family. Runs entirely in your browser and works offline as a Progressive Web App.

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