Topic

James Webb Space Telescope

Hubble Space Telescope image of the spiral galaxy NGC 5584, its arms dotted with blue star-forming regions.

The universe is expanding at two different speeds

Measure the expansion rate from the early universe and you get one number. Measure it from nearby galaxies and you get another. A decade of better data has made the gap harder to explain away.

CosmosLens EditorsNovember 8, 20265 min read

Illustration of a blue ocean-covered planet with a thick hazy atmosphere, lit from one side by a distant red star.

PlanetsAnalysis

How to read the sky of a world you will never see

Astronomers can now measure the gases around a planet 124 light-years away. The rise and fall of the claims about K2-18b show what that technique can do, and how easily it can be over-read.

CosmosLens EditorsNovember 8, 20264 min read