Expanding Universe

Choose any galaxy as your viewpoint and watch distance, recession speed and redshift grow as space expands.

Accelerating ΛCDM-style UniverseExpanding · accelerating

ObserverUnbound galaxyBound local groupClick a galaxy to observe from it

Scale factor1.000

Cosmic age13.8 Gyr

Hubble parameter70.0 km/s/Mpc

Selected distance—

Redshift—

Scale factor against cosmic time

Hubble diagram

No central galaxy

Changing observer gives the same broad result: distant unbound galaxies recede. The Big Bang was an expansion of space everywhere, not an explosion from one central point.

Hubble’s law

For nearby galaxies, recession speed is approximately v = H₀d. More distant objects require a fuller cosmological treatment.

Expansion and binding

Gravity and other forces keep galaxies, solar systems and many local groups bound. Cosmic expansion dominates across sufficiently large, unbound distances.

Model note: This is a qualitative scale-factor laboratory, not a precision cosmology solver. Distances, velocities and redshifts are educational approximations; superluminal recession is expansion of space, not local motion through space.