🌠 Gallery

How Far Are the Stars?

🔭 How do we measure the distance to stars without a ruler? As Earth moves to the opposite side over half a year, nearby stars seem to shift side to side. The larger the shift, the closer the star, and parallax × distance is always 1! 💡 But a brighter-looking star isn't always truly brighter. You can create a star that is 4 times brighter but 6 times farther away so it looks dimmer. Try finding a star that looks identical to a reference star in two ways. 🌌 Farther galaxies move away faster. Even if you move the observer from A to D, the rule stays the same — so the universe has no center! This app was built with code · Remix it to add your own stars!