universe

2. An extremely luminous and active galactic nucleus, powered by a supermassive black hole.
4. Hole A region of space where the gravitational pull is so strong that nothing, not even light, can escape.
6. A giant cloud of dust and gas in space, often the birthplace of stars.
7. Matter A type of matter that does not emit, absorb, or reflect light, making it invisible and detectable only via its gravitational effects.
8. Microwave Background (CMB) The thermal radiation left over from the Big Bang, detectable in every direction of the universe.
9. A planet that orbits a star outside our solar system.

1. A massive system of stars, stellar remnants, interstellar gas, and dark matter, bound together by gravity.
3. A powerful and luminous explosion that occurs during the last stages of a massive star's life cycle.
5. The increase in the wavelength of light from an object moving away from the observer, indicating its recession.
10. Year The distance that light travels in a vacuum in one year, roughly 5.88 trillion miles (9.46 trillion kilometers).