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Unit 12 lessons
Unit 22 lessons
The Phases of the Moon
An easy explanation of why the Moon changes shape during the month and how people once used it as a calendar.
Life Aboard the Space Station
A look at the daily life of astronauts living and working on the International Space Station.
Unit 32 lessons
First Footprints on the Moon
The story of the Apollo Eleven mission and the first human footsteps on the Moon.
Telescopes and Distant Galaxies
How telescopes have grown from simple glass lenses into giant space observatories that reveal distant galaxies.
Unit 42 lessons
Searching for Life on Mars
Why scientists believe Mars may once have supported life and how robot rovers search for evidence today.
Inside the World of Black Holes
An exploration of how black holes form, why nothing escapes them and how astronomers manage to study them.
Unit 52 lessons
The New Business of Spaceflight
How private companies, reusable rockets and space tourism are changing humanity's path into orbit and beyond.
The Mystery of Dark Matter
A deep dive into dark matter, the invisible substance that holds galaxies together yet defeats every detector.
Unit 62 lessons
Unit 72 lessons
Stars and Constellations in the Night Sky
An easy talk about stars, constellations, and how people have used them for centuries.
Daily Life on the Space Station
A description of how astronauts eat, sleep, work, and exercise aboard the International Space Station.
Unit 82 lessons
Robot Rovers Exploring Mars
An account of how robotic rovers and a small helicopter are exploring the surface of Mars.
What Happens Near a Black Hole
An explanation of how black holes form, how scientists observe them, and why time behaves strangely near them.
Unit 92 lessons
Unit 102 lessons
Settling Humans on Mars
A discussion of commercial spaceflight and the challenges and arguments surrounding a future colony on Mars.
Echoes of the Big Bang
A cosmological narrative tracing the universe from the Big Bang to the unresolved mysteries of dark matter and dark energy.
Unit 112 lessons
Unit 122 lessons
Unit 132 lessons
Unit 142 lessons
Unit 152 lessons
Unit 162 lessons
Unit 172 lessons
Unit 182 lessons
Unit 192 lessons
Unit 202 lessons
Unit 212 lessons
Unit 222 lessons
Counting Shooting Stars
A speaker explains what shooting stars really are and remembers watching a meteor shower with their grandfather.
Satellites Working Above Us
A talk about how satellites help everyday life, from weather forecasts to navigation, and the problem of space junk.
Unit 232 lessons
Unit 242 lessons
The Webb Telescope's Deep Fields
An introduction to the James Webb Space Telescope, how it works, and what it has discovered.
Dark Energy and the Cosmic Push
A lecture on dark energy, the mysterious force that seems to be pushing the universe apart ever faster.
Unit 252 lessons
Why Pluto Lost Its Status
An account of how Pluto was discovered, why it was reclassified as a dwarf planet, and what a spacecraft found there.
The Great Silence
A reflection on the search for extraterrestrial intelligence and why the universe has so far remained silent.