Space

3. Extremely energetic explosion observed in distant galaxies, often from collapsing stars.
4. Study of life in the universe, including the possibility of extraterrestrial life.
6. Hypothetical tunnel connecting distant parts of space-time.
8. A planet that orbits a star outside our solar system.
9. Stellar remnant left after a low or medium mass star expels its outer layers.
11. Opposite form of matter with reversed charge; annihilates on contact with regular matter.
12. Sudden burst of radiation and particles from the Sun’s surface.
15. A type of neutron star with an extremely powerful magnetic field.
16. Extremely bright and distant active galactic nucleus powered by a supermassive black hole.
17. A point in space-time where density becomes infinite, such as at the center of a black hole.
18. Referring to the space between stars.
20. Boundary around a black hole beyond which nothing can escape.

1. Theoretical stretching of objects into thin shapes by extreme gravitational forces near a black hole.
2. Scientific study of the origin, evolution, and structure of the universe.
5. Hypothetical collection of multiple or infinite universes including our own.
7. Dense remnant of a massive star composed almost entirely of neutrons.
10. Bending of light around massive objects, used to detect dark matter and distant galaxies.
13. Invisible substance inferred from gravitational effects; makes up most of the universe's mass.
14. Hypothetical particle that travels faster than light.
19. Phenomenon where light stretches to longer wavelengths as objects move away in an expanding universe.