Across
- 4. Large balls of gas that generate energy through nuclear fusion.
- 7. The smallest galaxies have an _____ shape.
- 8. Pluto is now considered a _____.
- 10. Planet where all living things can survive.
- 11. _____ is about the same size as Earth and is sometimes called the "morning star".
- 12. Objects that orbit planets.
- 14. Planets outside our solar system.
- 15. Smaller, irregular, rocky objects that orbit stars.
- 17. The star in our solar system.
- 18. This planet has large seas of liquified hydrogen.
- 19. _____ has 146 moons.
- 20. Our galaxy is called the _____ galaxy.
Down
- 1. Planets must _____ a star.
- 2. Clusters of billions of stars held together by gravity.
- 3. Any of the large bodies that revolve around the Sun in the solar system.
- 5. The largest storm in the solar system.
- 6. Planet named after the Roman god of the underworld.
- 9. Everything, including all of space, time and matter.
- 13. Sometimes called dirty snowballs.
- 15. Study of all the objects outside the Earth's atmosphere.
- 16. The force of attraction responsible for holding planets in orbit.