Across
- 1. the mean distance from the center of the earth to the center of the sun.
- 3. a unit of astronomical distance equivalent to the distance that light travels in one year
- 4. theory that suggests that the universe was created as a result of an extremely large explosion.
- 6. the smallest planet in the Solar System and the closest to the Sun.
- 7. a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
- 12. a star showing a sudden large increase in brightness and then slowly returning to its original state over a few months.
- 13. a streak of light in the sky caused by a meteoroid crashing through Earth's atmosphere.
- 14. the fourth planet from the Sun and the second-smallest planet in the Solar System
- 15. the fifth planet from the Sun and the largest in the Solar System.
- 21. a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
- 23. a very large star that is even brighter than a giant, often despite being relatively cool.
- 25. a closed plane curve generated by a point moving in such a way that the sums of its distances from two fixed points is a constant
- 26. the eighth and farthest-known Solar planet from the Sun
- 27. an eclipse in which the sun is obscured by the moon.
- 28. the planet on which we live
- 29. any theory of the structure of the solar system (or the universe) in which Earth is assumed to be at the centre of it all.
- 30. the systems of stars and interstellar matter that make up the universe
- 31. a small very dense star that is typically the size of a planet.
- 35. any natural solid object that survived the meteor phase in a gaseous atmosphere without being completely vaporized.
- 36. the branch of science which deals with celestial objects
Down
- 2. a planet that is composed primarily of silicate rocks or metals.
- 5. a small body moving in the solar system that would become a meteor if it entered the earth's atmosphere.
- 8. the changes in frequency of any kind of sound or light wave produced by a moving source with respect to an observer.
- 9. the sixth planet from the Sun and the second-largest in the Solar System
- 10. a minute planet; a body that could or did come together with many others under gravitation to form a planet.
- 11. any of the giant planets in our solar system
- 13. a continuous and distinctive band of stars that appears on plots of stellar color versus brightness.
- 16. the seventh planet from the Sun
- 17. having or representing the sun as the center, as in the accepted astronomical model of the solar system.
- 18. when the Moon moves into the Earth's shadow.
- 19. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
- 20. a very large star of high luminosity and low surface temperature.
- 22. frozen leftovers from the formation of the solar system composed of dust, rock, and ices.
- 24. a contracting mass of gas which represents an early stage in the formation of a star, before nucleosynthesis has begun.
- 32. a small rocky body orbiting the sun
- 33. the second planet from the Sun
- 34. a region of space having a gravitational field so intense that no matter or radiation can escape.