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Across 3. A star's spectral class is most dependent on its color and _____. 5. Named after the Roman God of the sea and is a sea blue color due to the methane gas in its atmosphere. 8. This planet is not round. It is an oblate spheroid, flattened at the poles and bulging at the equator. 9. A collection of gas, dust, and stars all bound together by gravity. 10. Nothing can escape the effects of this (written as one word). 16. A _____ blob. 18. The sun is composed of 90% _____. 19. ____ Forces tend to cluster galaxies together in groups. 20. Amorphous shapes. 23. A main sequence star that is a hot ball of gas in space that produces its own energy. 24. Are mostly made up of iron or silicate materials. Hit the earth. 27. From smallest to largest, list the objects: meteoroid, asteroid, ____ planet, planet. 29. There are eight of these in our solar system. 31. Known for its beautiful rings.

Down 1. Stars in center fall along a bar shape, with arms spiraling away from it. (written as one word) 2. The biggest planet in our solar system. 4. Flash of light from rocks burning up in the atmosphere 6. The red planet because it is rusty. There is a lot of iron in the soil. 7. The center of our Milky Way galaxy is ____ A. 11. A Hertzsprung-Russell diagram is a eaxy way to see the relationshio between _____ and brightness of stars. 12. When a comet nears the Sun, materials in the nucleus evaporates, forming a cloud of gas 13. Often composed of carbon or silicates and most often found in belts 14. Smaller than asteroids and not usually found in asteroid belt. 15. At the center of the ____ galaxy there is a black hole with a mass 30 million times the mass of the sun. 17. The closest planet to the sun. 21. The amount of _____ affects the galaxy shape. 22. Composed of frozen gases and often have elliptical orbits. 25. Bright center with arms spiraling away from it 26. The ____ of a comet is only visible when it is near the Sun. 28. A beautiful looking planet with a deadly atmosphere. 30. The 7th planet that is named after a Greek God and has 27 known satellites.