Across
- 5. the time it takes for an object to orbit another object; Earth’s revolution around the Sun is 365.24 days
- 7. a celestial body made of hot gases, mainly hydrogen and some helium
- 9. a huge collection of stars, planets, gas, and dust that is held together by gravity
- 10. an object in space that ranges in size from a tiny speck, like a grain of sand, to 500 km wide; most asteroids originate in the asteroid belt between Mars and Jupiter
- 11. an object composed of rocky material, ice, and gas; comes from the Kuiper Belt or Oort Cloud
- 12. the turning of an object around an imaginary axis running through it; Earth’s rotation around its axis is 24 h
- 14. a piece of rock moving through space
- 16. a small, dim, hot star
- 17. a star’s total energy output per second; its power in joules per second
- 19. a meteoroid that is large enough to pass through Earth’s atmosphere and reach the ground, without being totally burned up
Down
- 1. a scientist who studies astronomy
- 2. a massive explosion in which the entire outer portion of a star is blown off
- 3. the monthly progression of changes in the appearance of the Moon that result from different portions of the Moon’s sunlit side being visible from Earth
- 4. an artificial (human-made) object or vehicle that orbits Earth, the Moon, or other celestial bodies; also, a celestial body that orbits another body of larger size (for example, the Moon is Earth’s natural satellite)
- 6. the distance that light travels in one year, about 9.5 × 1012 km The 12 is supposed to be on the top right corner of 10
- 7. a group of planets that circle one or more stars
- 8. an object that orbits one or more stars (and is not a star itself), is spherical, and does not share its orbit with another object
- 13. the galaxy that includes the solar system; appears as a hazy white band in the night sky
- 15. a way of showing days, organized into a schedule of larger units of time such as weeks, months, seasons, or years; usually a table or a chart
- 18. a meteoroid that hits Earth’s atmosphere and burns up