The Black Holes Reference Guide

Our own anatomy drawing, the Schwarzschild radius, the four kinds and the famous black holes, Sagittarius A*, the first pictures, gravitational waves, who’s who, a timeline from 1783 to 2024, every place the sources disagree, myths and a glossary.

What’s inside:

• Black holes at a glance
• The parts of a black hole
• How big is a black hole?
• Four kinds of black hole
• Famous black holes
• Sagittarius A*
• A telescope the size of Earth
• Hearing two black holes collide
• Who’s who
• From dark stars to a photograph
• Where good sources disagree
• Myths, checked
• Words you will meet
• Credits, licence and sources

Pages: 15 (A4) / 15 (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 and a few drawings are dark, so print those in colour or skip them to save ink.

Every fact is written in our own words and checked against named sources from NASA (NASA Science, NASA Space Place and the Chandra X-ray Observatory), ESO, ESA, the Nobel Prize site, LIGO Caltech, Encyclopaedia Britannica and the Royal Society (checked 10 Nov 2026); the sources are listed on the credits page. Where sources give different figures, each is shown with its source. Our own opinions are clearly labelled.

Drawings and charts are our own. Photos are from Wikimedia Commons under Creative Commons or public-domain terms, credited on the credits page. Not affiliated with or endorsed by NASA, ESO, ESA, the Event Horizon Telescope Collaboration, LIGO, the Nobel Foundation, Encyclopaedia Britannica, the Royal Society or any other organisation, scientist or photographer named here.

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 black-holes.galaxies.im. Questions: info@reallybyte.com

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