Part 1 of 5 · freeIntroduction
How far away is the Moon? It can be measured with lasers. During the Apollo missions, astronauts placed special reflectors on the lunar surface. From Earth, scientists fire laser pulses at them and time how long the light takes to come back. The result: the Moon sits on average about 385,000 km away from us.
But that distance is not fixed. Every year, the Moon moves about 3.8 cm farther away, roughly as fast as our fingernails grow. From one year to the next, the change is tiny. Over millions of years, it adds up. So what could possibly be pushing the Moon away from us?
The rest is in the Sophia app.The remaining parts, the open-book quiz and the full glossary. Free to start; Premium unlocks everything.
- 2The Moon lifts the oceans
- 3Earth pushes the Moon
- 4Earth is slowing down too
- 5The end of total eclipses
Open-book quiz8 questions whose answers are in the text.
Glossary6 terms explained in a tap.
30 languagesThe same course, from French to Japanese.
