Across
- 3. Robotic explorer vehicle (Mars rover, etc.)
- 4. Reflected sound (or signal)
- 5. A very long time
- 6. Space stuff between stars
- 9. As in “dwarf planet”
- 10. Detection system using radio waves
- 11. To block out (as the Moon can the Sun)
- 13. A repeating oscillation (light is one)
- 15. Charged atom
- 17. Related to the Moon
- 19. High-energy radiation type
- 20. Huge star systems like the Milky Way
- 21. Large body of saltwater
- 22. Where clouds (and stars) appear
- 23. Beam (as in “gamma ray”)
- 27. What a clock measures
- 28. Tool for viewing distant objects in space
- 31. Luminous balls of plasma
- 32. Particle of light
- 36. Star pattern in the night sky
- 37. Earth’s natural satellite
- 39. What we breathe
- 40. Lifting machine; also a bird
- 41. The red planet
- 42. Our star
Down
- 1. Icy body with a tail near the Sun
- 2. Rock containing metal
- 6. Genetic material
- 7. Vehicle designed for space travel
- 8. Electron regions in atoms (chemistry term)
- 12. Sudden brightening star event
- 14. Book of maps; also a Titan in myth
- 16. Sauce (playful filler)
- 17. Focused beam of light
- 18. Saturn feature, for example
- 19. One state of matter
- 24. Rocky bodies orbiting the Sun
- 25. Frozen water
- 26. Unidentified flying object
- 29. Place for experiments
- 30. Curved line segment
- 31. Objects that orbit a planet (often artificial)
- 33. Relating to ions
- 34. Navigation aid
- 35. Relating to Earth’s ends (or opposite charges)
- 37. Iron, gold, etc. (common crossword fill)
- 38. Basic unit of matter
- 40. The universe (poetic/scientific)