How the Cosmos Works
Unravel the mechanics of the universe from your own backyard to deep space. Discover why orbits work, how dying stars forged the elements in your blood, and what warped spacetime reveals about reality.
Like Duolingo, but for How the Cosmos Works. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
22 levels across 3 sections, about 44 minutes end to end, roughly 9 days at five minutes a day. It moves through Looking Up: Motion and Gravity in Action, Decoding Starlight and Dying Stars, and The Architecture and Scale of the Universe. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in How the Cosmos Works
- Steady light is a reliable visual cue that you are looking at a planet rather than a star
- Stars are so distant they appear as razor-thin points of light easily distorted by shifting air
- Planets are close enough to appear as small disks, which averages out atmospheric turbulence
- The sky's daily movement is an illusion caused by Earth spinning on its axis
- Earth rotates eastward, making celestial objects appear to move westward
- Light travels at a fast but finite speed across space
- The light we see right now left distant stars years, centuries, or millennia ago
- Looking farther into space inherently means looking further back into past time
- Planets orbit the Sun alongside Earth on nearly the same flat plane
- Because planets are orbiting nearby, their positions slowly drift against the distant starry background
- Distant stars are so far away that their relative positions appear fixed to human eyes
- One half of the Moon is always lit by the Sun, regardless of phase
- Phases are simply our changing vantage point of that sunlit side as the Moon loops around Earth
- Earth's shadow only falls on the Moon during a rare lunar eclipse, not during ordinary phases
- Gravity pulls the satellite down while sideways speed carries it forward
- The satellite drops toward Earth at the exact same rate the planet's round surface curves away
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives How the Cosmos Works the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
Why do distant stars twinkle when you look up at night?
Get it right to open this lesson and 21 more in the app.
How to learn How the Cosmos Works, step by step
Go in order. 22 short levels across 3 sections, about 44 minutes in all, five minutes a day.
- 1
Looking Up: Motion and Gravity in Action
- Making Sense of the Night Sky
- Why Orbiting Things Don't Crash Down
- 2
Decoding Starlight and Dying Stars
- Reading the Secret Messages in Starlight
- How Stars Live and Die
- Extreme Gravity and Bent Space
- 3
The Architecture and Scale of the Universe
- Galaxies and the Hidden Web of Matter
- The Expanding Universe and Cosmic Time
3 sections · 7 units · 22 levels. Built to play, not to enroll.
Questions about How the Cosmos Works
How do I learn How the Cosmos Works?
Go in order: start with Looking Up: Motion and Gravity in Action, then Decoding Starlight and Dying Stars, then The Architecture and Scale of the Universe. On Tomo that's 22 short levels, about 44 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for How the Cosmos Works?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. How the Cosmos Works is one of its free courses, and you can type any other topic to get a course of your own.
Is the How the Cosmos Works course free?
Yes. How the Cosmos Works is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn How the Cosmos Works?
22 levels across 3 sections, about 44 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start How the Cosmos Works?
No. It's pitched at a beginner level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
How the Cosmos Works is taught in the Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
More Science on Tomo
How Space Works
Make sense of the night sky, journey through our solar system, and uncover the grand forces that shape stars, galaxies, and the universe itself.
How Space Works
Understand what you see when you look up at the night sky and how the cosmos functions. Learn the mechanics of orbits, the lifecycle of stars, and the vast architecture of the universe.
Decoding the Universe
Learn to read the messages hidden in starlight and understand the invisible forces that shape our cosmos.
The Mechanics of Space
Move beyond basic planet trivia to understand orbital dynamics, stellar engines, and the geometry of the cosmos. Discover how spacecraft navigate the void, how stars forge matter, and what drives cosmic expansion.
The Beginning of the Universe
Trace the cosmos back to its very first moments using the clues hidden in today's night sky. Discover how expanding space, ancient starlight, and cosmic static reveal the origin of time, matter, and everything we see.
Stargazing and the Hidden Universe
Learn to read the night sky like a map and discover the secret messages hidden in starlight. From finding famous constellations to 'seeing' invisible radiation, you'll view the cosmos in a whole new light.
Start How the Cosmos Works today.
Download Tomo, search How the Cosmos Works, and play your first lesson in under a minute.