Astronomy history explainer
I’m Catalina. Every Sunday I explain one thing people worked out about the sky and the steps it needed first. I also sell reading maps, classroom sheets and two video courses.
Read first
Every letter names the steps it builds on. Start at the top, pick a thread and follow the lines.
Why the planets seemed to wander
Aug 2026
Light
What starlight tells us
Branches from How a prism splits light · Rejoins at Why the galaxies are moving away
Sep 2026
Oct 2026
Distance
How far away things are
Branches from The first telescopes, and what they showed
Measuring the distance to a star
Sep 2026
Why the galaxies are moving away
Nov 2026
Planets
Orbits and new worlds
Branches from Why the planets seemed to wander · Rejoins at Finding planets around other stars
Kepler and the shape of an orbit
Oct 2026
Oct 2026
Sep 2026
Newsletter
One discovery each Sunday, and the steps that led to it.
How a tiny dip in a star's light, measured night after night, became the way we find new worlds.
Blinking stars gave the distances and starlight gave the speeds. Put together, they showed a growing universe.
Uranus kept drifting off its path, so two people worked out where an unseen planet had to be.
A careful count of stars that brighten and fade gave us a ruler for the far sky.
Once the dark lines in sunlight were matched to flames in a lab, the stars could be read like a label.
Years of numbers about Mars, and the moment a circle gave way to a stretched one.
Downloads, a course and merch
Downloads arrive by email. Merch is printed to order and shipped by Printful.
Online course
Video course · 8 lessons
Eight lessons in order, from the first calendars to planets around other stars.
About
I live in a small town in the Atacama desert in Chile, where the sky is dark enough to see the Milky Way cast a shadow. I taught physics at a secondary school for twelve years, and now I give night sky talks for visitors.
On those nights the same question keeps coming: how do we know? How do we know how far away a star is, or what it is made of? So I started a weekly letter. Each one explains a single discovery and names the earlier steps it stood on.
I write plainly and I show my sources. I make printable sheets for teachers and curious readers, and two short video courses for anyone who wants the whole story in order.
