black hole
The term 'agujero negro' is a phrase in Spanish that translates to 'black hole' in English. A black hole is a region of spacetime where gravity is so strong that nothing, not even particles and electromagnetic radiation such as light, can escape from it. The term 'black hole' is largely attributed to the fact that it absorbs all the light that comes towards it, and it reflects nothing, rendering it effectively invisible and giving it a dark appearance.
The black hole in the center of the galaxy is huge.
This sentence uses 'agujero negro' as a noun, referring to a specific phenomenom in the universe. In this precise context, it refers to a black hole that is located in the center of a galaxy and has a large dimension.
The black hole is an astronomical object of great density.
This sentence uses 'agujero negro' as a subject. The statement observes the physical property of black holes, which refers to them being objects with very high density.
When talking about a black hole, people often think about the mysteries of the universe.
This sentence uses 'agujero negro' as a noun. In this context, it indicates the fact that black holes are often associated with the mysteries of the universe and space.