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World 7 · Around a black hole · 10 min · PRO

The last stable orbit

Why nothing circles closer than 6M for long

PRO · Orbits & Gravity

World 7: Around a black hole 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.

  • Orbits that do not close
  • Light that escapes, light that falls in
  • Slow clocks near a black hole
PRO includes
  • All 26 labs — every world, every lesson
  • Practice exams and certificates

$8.33/mo, billed yearly ($99.99) · or $39.99 monthly

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