Horizon
- (Past) Horizon:
- Future Horizon:
Explanations:
Past Horizon: the distance the light travels since the beginning of
the universe to the present moment.
Future Horizon: the distance the light travels since the present
moment until the infinite future (it is finite if the expansion of the
universe accelerates).
Legend:
- Mpc = million parsecs
- kpc = thousand parsecs
- Mlyr = million light years
- klyr = thousand light years