World 4 · Deep Space: Multi-Body · 8 min · PROLagrange points
Where forces balance
PRO · Orbits & Gravity
World 4: Deep Space: Multi-Body is part of PRO
The first world of Orbits & Gravity is free. PRO opens the other 34 lessons in 6 worlds — simulations, quizzes and all.
PRO includes
- All 26 labs — every world, every lesson
- Practice exams and certificates
$8.33/mo, billed yearly ($99.99) · or $39.99 monthly