Ordinary Matter Makes Up Only About 5% of the Universe

In 1929 he found that distant galaxies are moving away from us faster the farther they are.

Discovered in 1965 by Arno Penzias and Robert Wilson, it dates from about 380,000 years after the Big Bang.

Scientists estimate this age by measuring the cosmic microwave background and the expansion rate.

Although the universe is about 13.8 billion years old, its expansion means the observable region is much larger than that age suggests.