Luminosity distance: distance obtained by comparing the observed flux (or apparent magnitude) with the emitted luminosity (or absolute magnitude): f = L/(4πdL2) or m – M = 5 log(dL/10)..
The basic relationship (at non-relativistic speeds) is that v=H0d where v is the velocity implied by the redshift and d is the distance.
The constant of proportionality H0∼70 km/s per Mpc..
In standard cosmology, comoving distance and proper distance are two closely related distance measures used by cosmologists to measure distances between objects; the comoving distance is the proper distance at the present time..
The time in the past at which the light we now receive from a distant object was emitted is called the look-back time.
When astronomers discuss events in distant objects, they take for granted that the actual event occurred earlier because of light travel time..
In a flat universe, the proper distance to an object is just its coordinate distance, s(t) = a(t) \xb7 r..
This cosmology calculator uses the program cosmic to calculate a number of parameters for an object at a redshift z, using the given ΛCDM cosmology
The output of cosmic is shown below the form
A calculator that takes light travel time and computes the redshift
There is also an advanced version of my Cosmology Calculator
Cosmology is the study of the origin, current state, and future of our Universe
This field has been revolutionized by many discoveries made during the past century
There are a few different definitions of "distance" in cosmology which are all asymptotic one to another for small redshifts
The expressions for these distances are most practical when written as functions of redshift , since redshift is always the observable
They can also be written as functions of scale factor
