I built a space travel calculator using Vanilla JavaScript

Details

External ID

46742285

Source

HN

Company

—

Product

I built a space travel calculator using Vanilla JavaScript

Website domain

vercel.app

Launched

Jan. 24, 2026

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Upvotes

54

Upvotes percentile

0.8096179183135704

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Fetched at

Sept. 7, 2026, 9:25 p.m.

Updated at

Sept. 7, 2026, 9:25 p.m.

Description

I built this because measuring my age in years felt boring—I wanted to see the kilometers.The first version only used Earth's orbital speed (~30km/s), but the number moved too slowly. To get the "existential dread" feeling, I switched to using the Milky Way's velocity relative to the CMB (~600km/s). The math takes some liberties (using scalar sum instead of vector) to make the speed feel "fast," but it gets the point across.Under the hood, it's a single HTML file with zero dependencies. No React, no build step. The main challenge was the canvas starfield—I had to pre-allocate the star objects to stop the garbage collector from causing stutters on mobile.Let me know if the physics makes you angry or if the stars run smooth on your device.

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