The Big Bang Reference Guide

Our own drawings and a plain, sourced account of how the universe began: the first seconds and minutes, the cosmic microwave background, the evidence astronomers use, and the notes where good sources still disagree about dates and wording.

What’s inside:

- What was the Big Bang?

- How old is the universe?

- The first seconds and minutes

- An expanding universe, and what fills it today

- The cosmic microwave background

- The evidence, and how the idea grew

- Credits, licence and sources

Pages: 17 (A4) / 17 (US Letter). Formats: A4 (210 × 297 mm) and US Letter (8.5 × 11 in), both PDFs included in one zip.

Printing: Print at 100% / actual size on A4 or US Letter. Most inside pages use light backgrounds and print well in black and white; the cover is dark, so print that in colour or skip it to save ink.

Every fact is written in our own words and checked against named sources from NASA and Encyclopaedia Britannica (checked 14 Nov 2026); the sources are listed on the credits page. Where sources give different figures, each is shown with its source.

Drawings are our own, simplified and not to scale. This pack is independent and is not affiliated with, or endorsed by, NASA or Encyclopaedia Britannica.

Licence: personal use. Print as many copies as you need for yourself and your household. Please don’t resell, re-upload or share it publicly. For club, school or commercial use, please email info@reallybyte.com.

Made by REALLYBYTE, the team behind big-bang.galaxies.im. Questions: info@reallybyte.com

This is a digital download: no physical item will be shipped.

Price: $5.99 USD.