Proper Distance Rechner — Formel
## Proper Distance
The proper distance is the physical distance between two objects at a particular moment in cosmic time.
### Relation
**d_proper = a(t) * d_comoving**
- *a(t)* is the cosmic scale factor (a = 1 today)
- *d_comoving* is the comoving distance
At the present epoch a = 1, so proper distance equals comoving distance. In the past (a < 1) the physical distance was smaller.
The proper distance is the physical distance between two objects at a particular moment in cosmic time.
### Relation
**d_proper = a(t) * d_comoving**
- *a(t)* is the cosmic scale factor (a = 1 today)
- *d_comoving* is the comoving distance
At the present epoch a = 1, so proper distance equals comoving distance. In the past (a < 1) the physical distance was smaller.
Lösungsbeispiel
A galaxy with comoving distance 428 Mpc observed at the present epoch (a = 1).
- d_proper = a(t) * d_comoving
- d_proper = 1.0 * 428
- d_proper = 428 Mpc ≈ 1396 Mly