The age of the universe

2. The speed at which a galaxy moves away from an observer due to the expansion of the universe.
5. The pattern of colors or wavelengths produced when light is separated, used to study stars and galaxies.
7. The shortening of light wavelengths when an object moves toward the observer.
8. The astronomer who discovered that galaxies are moving away from us and that the universe is expanding.
10. A possible future of the universe where expansion stops and everything collapses back together.
12. A mysterious form of energy thought to be responsible for the accelerating expansion of the universe.
13. The stretching of light toward longer (red) wavelengths when an object in space is moving away from us.
14. Invisible matter that does not emit light but is detected through its gravitational effects on galaxies and cosmic structures.
15. The theory that the universe began from an extremely hot and dense state and has been expanding ever since.

1. The change in the observed frequency or wavelength of a wave due to the motion of the source relative to the observer.
3. The exact density of the universe needed to make its expansion slow down and eventually stop (border between open and closed universe).
4. The scientist who used one of the first telescopes for astronomy about 300 years before modern cosmology.
6. The bending of light caused by massive objects like galaxies, acting like a cosmic magnifying glass.
9. The number that describes how fast the universe is expanding, relating galaxy distance to recession velocity.
11. The observation that galaxies move away faster as their distance from Earth increases.