crossword

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Across
  1. 2. t bu An extremely dense region in space where gravity is so strong that nothing, not even light, can escape.
  2. 6. Specific dark or bright lines in a spectrum that act as "fingerprints," revealing what elements a star is made of.
  3. 7. The branch of astronomy that deals with the origin, structure, and evolution of the entire universe
  4. 8. The general change in frequency or wavelength of a wave (light or sound) caused by the motion of the source relative to the observer.
  5. 9. Subatomic particles that have the same mass as normal matter but opposite electrical charges (e.g., positrons).
  6. 13. A type of "standard candle" star that pulses at a regular rate, allowing astronomers to measure vast cosmic distances accurately.
  7. 15. The force that governs the interaction between electrically charged particles; it is responsible for light, electricity, and magnetism.
  8. 19. The standard SI unit for temperature in science; is "absolute zero," where all molecular motion stops.
  9. 22. The "afterglow" of the Big Bang; ancient light (now stretched into microwaves) that fills all of space.
  10. 25. A term used to describe the incredibly hot, dense, and opaque state of the early universe.
  11. 26. The theoretical starting point of the Big Bang; a point of infinite density and heat where the laws of physics as we know them break down
  12. 27. The apparent shift in a star's position when viewed from different sides of Earth’s orbit, used to calculate distance.
  13. 28. The long period of the universe’s history where the energy of matter became more dominant than the energy of radiation.
  14. 30. The shortening of light waves toward the blue end of the spectrum as an object moves toward the observer.
  15. 31. A scientific instrument used to measure the intensity or brightness of light.
Down
  1. 1. (First Law): Also known as the Law of Conservation of Energy, it states that energy cannot be created or destroyed, only transformed.
  2. 3. The process where light atomic nuclei join to form a heavier nucleus (like Hydrogen into Helium), releasing massive amounts of energy.
  3. 4. A specific pattern in the Cosmic Background Radiation that shows our galaxy's motion relative to the rest of the universe.
  4. 5. Density: The specific "tipping point" density required for the gravity of the universe to eventually stop its expansion.
  5. 10. A measure of the average kinetic energy (speed) of the particles in a substance.
  6. 11. The fourth dimension that began at the Big Bang; in physics, it is woven together with space to form "spacetime."
  7. 12. A period of extremely rapid, exponential expansion that occurred a fraction of a second after the Big Bang, smoothing out the universe
  8. 14. A famous space-based observatory that helped prove the universe’s expansion is accelerating.
  9. 16. The leading scientific explanation for how the universe began—expanding from a single, high-density point about 13.8 billion years ago
  10. 17. The four basic interactions that govern all matter: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force.
  11. 18. A massive system containing millions or billions of stars, gas, and dust, all held together by gravity.
  12. 20. The giant, empty "bubbles" in space that contain very few galaxies.
  13. 21. Invisible matter that does not emit light is known to exist because its gravity affects the motion of galaxies.
  14. 23. (shape): The overall geometry of the universe (flat, open, or closed), determined by the amount of matter and energy within it.
  15. 24. A unit of distance (not time) representing how far light travels in one year—about 9.46 trillion kilometers.
  16. 29. The stretching of light waves toward the red end of the spectrum as an object moves away from the observer.