Astronomy: Reading the Night Sky
Learn to read the sky like an astronomer, from locating planets with the naked eye to decoding the lifecycles of stars and distant galaxies. This course equips you with a solid working knowledge of how our solar system moves, how cosmic matter evolves, and how light reveals the shape of our expanding universe.
Like Duolingo, but for Astronomy: Reading the Night Sky. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
24 levels across 4 sections, about 48 minutes end to end, roughly 10 days at five minutes a day. It moves through Finding Your Bearings in the Sky, Touring Our Solar System, The Lives and Deaths of Stars, and The Vast and Expanding Universe. It starts from scratch.
Free forever · No credit card · iPhone & Android

Key ideas in Astronomy: Reading the Night Sky
- Earth's daily spin on its axis makes stars appear to rise in the east and set in the west over the course of a night
- Earth's yearly orbit around the Sun shifts our night view slightly each day, bringing different constellations into view with each season
- Asterisms are easily recognized shapes (like the Big Dipper) that astronomers use as landmarks
- The two outer stars in the Big Dipper's bowl point directly across the sky toward Polaris
- Polaris is not particularly bright, making signpost asterisms essential for finding it
- Stars appear as tiny pinpoint specks of light whose rays easily bend and flicker through turbulent air, causing them to twinkle
- Planets are close enough to appear as wider disks of light, so turbulent air cannot easily disrupt the whole beam, making them shine steadily
- Human eyes require about twenty to thirty minutes of unbroken darkness to reach full sensitivity for seeing faint stars
- Even a brief flash of white light from a phone or flashlight instantly destroys dark adaptation, forcing the biological reset to start over
- Stargazers use dim red light because red wavelengths do not disrupt night adaptation nearly as much
- How bright a star appears to your naked eye depends on both how much light it physically produces and how far away it is from Earth
- A dimmer, modest star can easily outshine a brilliant supergiant star in our sky if it happens to sit much closer to us
- Half of the Moon is always illuminated by sunlight, just like Earth
- Moon phases reflect how much of that illuminated daylit side is turned toward Earth as the Moon orbits us
- Earth's shadow plays no role in regular lunar phases; it only touches the Moon during a lunar eclipse
- The Moon's orbit is tilted about five degrees compared to Earth's orbit around the Sun
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 Astronomy: Reading the Night Sky 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 you see different star patterns in the summer sky than in the winter sky?
Get it right to open this lesson and 23 more in the app.
Where Astronomy: Reading the Night Sky takes you
- 1
Finding Your Bearings in the Sky
- Navigating the Sky with the Naked Eye
- Tracking the Dance of Moons and Planets
- 2
Touring Our Solar System
- Reading the Terrestrial Worlds and the Sun
- Surveying Gas Giants, Icy Moons, and Debris
- 3
The Lives and Deaths of Stars
- Decoding the Color, Lifespan, and Power of Stars
- Tracing Supernovas, Dense Remnants, and Black Holes
- 4
The Vast and Expanding Universe
- Mapping Galaxies and the Cosmic Web
- Measuring the Expanding Universe and Cosmic Time
4 sections · 8 units · 24 levels. Built to play, not to enroll.
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
Astronomy: Reading the Night Sky is taught in the Explain Like I'm 5 style: no big words. promise.. 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.
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Stars, Planets, and the Cosmic Void
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Start Astronomy: Reading the Night Sky today.
Download Tomo, search Astronomy: Reading the Night Sky, and play your first lesson in under a minute.