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World 6 · Stars and galaxies · 9 min · PRO

Sorting galaxies on Hubble’s tuning fork

Ellipticals, lenticulars, spirals, barred spirals and irregulars

PRO · Orbits & Gravity

World 6: Stars and galaxies 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.

  • Heavy stars burn out fast
  • The Sun as a red giant
  • White dwarf, neutron star or black hole?
  • Orbits that do not close
  • The last stable orbit
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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← White dwarf, neutron star or black hole?Orbits that do not close →

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