Expansion of the Universe: Galaxies Racing Apart

The universe has been expanding ever since the Big Bang, about 13.8 billion years ago.
Edwin Hubble’s 1929 discovery showed galaxies are moving away from us—the farther, the faster.
This motion is not galaxies flying through space, but space itself stretching.
The “redshift” of galaxy light is key evidence of this cosmic expansion.
The rate of expansion is described by the Hubble constant, still debated by scientists today.
In the late 1990s, astronomers discovered the expansion is accelerating, driven by dark energy.
Galaxies not bound by gravity will drift farther apart, leaving the universe emptier over time.
In billions of years, distant galaxies may slip beyond our cosmic horizon, invisible forever.
Expansion shapes the ultimate fate of the universe—whether endless growth, slowdown, or collapse.
Every look at the night sky is a glimpse of galaxies caught in this great cosmic race.