Topic

Big Bang

A deep field crowded with thousands of galaxies of many shapes and colours against black space, some stretched into arcs, with a few bright foreground stars showing six-pointed spikes.

CosmosExplainer

How old is the universe? 13.8 billion years, and three ways we know

The number comes from running the expansion of space backwards. We did that calculation ourselves, then checked it against the oldest stars, a clock that no expansion measurement can touch.

CosmosLens EditorsNovember 10, 20265 min read

Oval all-sky map of the cosmic microwave background, mottled with blue and orange-red spots representing tiny temperature differences.

CosmosExplainer

The oldest light remembers everything

The cosmic microwave background was released when the universe was 380,000 years old. Its faint ripples encode the universe’s age, contents and shape. Here is how to read them.

CosmosLens EditorsNovember 8, 20264 min read