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