1

123456789101112131415161718192021222324252627
Across
  1. 2. An instrument used to measure the brightness (intensity) of light from stars or other objects.
  2. 3. The shortening of light to bluer wavelengths, indicating an object is moving closer.
  3. 7. A change in the wavelength of light (or sound) caused by motion toward or away from the observer.
  4. 9. A dimension that allows events to be ordered from past to future; in cosmology, it is linked with space as spacetime.
  5. 13. Matter made of particles with opposite charges to normal matter (e.g., positrons instead of electrons).
  6. 14. Another name for the extremely hot, dense state of the universe just after the Big Bang.
  7. 16. A period in the early universe when matter (rather than radiation) dominated the behavior of the universe.
  8. 18. Invisible matter that does not emit light but exerts gravitational effects on galaxies and the universe.
  9. 19. A massive system of stars, gas, dust, and dark matter held together by gravity (like the Milky Way).
  10. 20. The study of the origin, structure, evolution, and fate of the universe as a whole.
  11. 22. The distance light travels in one year (about 9.46 trillion kilometers).
  12. 23. The scientific model describing the universe’s origin from a hot, dense state and its expansion over time.
  13. 24. The exact average density of matter needed for the universe to be flat (neither expanding forever too fast nor collapsing).
  14. 26. A measure of how fast particles are moving; in astronomy, it helps determine properties of stars and gas.
  15. 27. A method of measuring the distance to nearby stars by observing their apparent shift against distant background stars as Earth orbits the Sun.
Down
  1. 1. A pattern with two opposite parts (like hot and cold spots in cosmic background radiation).
  2. 4. A point of infinite density and gravity, such as at the center of a black hole or at the start of the Big Bang.
  3. 5. The stretching of light to longer (redder) wavelengths, usually indicating that an object is moving away.
  4. 6. Huge, nearly empty regions of space with very few galaxies.
  5. 8. A type of variable star whose brightness changes regularly, used to measure distances in space.
  6. 10. The overall geometry of the universe—whether it is flat, open (curved outward), or closed (curved inward).
  7. 11. A very rapid expansion of the universe that occurred a tiny fraction of a second after the Big Bang.
  8. 12. The process where light atomic nuclei combine to form heavier ones, releasing energy (this powers stars).
  9. 15. A region in space where gravity is so strong that not even light can escape.
  10. 17. A fundamental force involving electric and magnetic fields; it governs light and all electromagnetic radiation.
  11. 21. A temperature scale used in science where 0 K is absolute zero (the lowest possible temperature).
  12. 25. Energy cannot be created or destroyed—only transferred or changed in form.