Time, Cycles and the Solar System

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Across
  1. 4. Method used before H4 (5, 8)
  2. 7. The pointy part of a sundial (6)
  3. 8. A planet crossing in front of a star (7)
  4. 12. Solved the longitude problem (8)
  5. 13. Time as indicated by the Sun (8, 5, 4)
  6. 17. Difference between AST and MST (8, 2, 4)
  7. 18. Moons falling into line around a planet (7, 9)
  8. 19. Radius at which water can exist (10, 4)
  9. 20. Forces that pull on planets and moons (5)
  10. 21. Name for the ring-shaped early Solar System (14, 4)
  11. 22. Day and night of equal length (7)
  12. 25. Shape of the EOT graph (8)
Down
  1. 1. Method for discovering exoplanets (6, 8)
  2. 2. The Moon more than half-full (7)
  3. 3. The moon getting bigger (6)
  4. 5. Stable points in a two-body system (10)
  5. 6. Method for discovering exoplanets (10)
  6. 9. Point at which a moon is torn to shreds (5, 5)
  7. 10. A day that lasts 23h 56m (8)
  8. 11. Threshold for ice formation (5, 4)
  9. 13. Lumps of dust sticking together (9)
  10. 14. Time averaged out across the year (4, 5, 4)
  11. 15. Planets that formed beyond the frost line (3, 5)
  12. 16. Longest, or shortest, day (8)
  13. 23. A day that lasts 24 hours (7)
  14. 24. The Moon getting smaller (6)