Astronomers have long struggled with a troubling puzzle: a significant portion of normal matter in the universe appeared to ...

A never-before-seen image of the cosmic microwave background, combining data from the Atacama Cosmology Telescope (ACT) and ...

The halo is more extended that astronomers originally thought, and contains enough hydrogen gas to resolve the problem of the ...

Mysterious dark matter makes up 85 percent of matter in the universe, and of the remaining 15 percent, scientists couldn’t ...

A faint cosmic spin – one rotation per 500 billion years – could resolve the stubborn Hubble tension by tweaking standard ...

Cosmic microwave background data support cosmology’s standard model but retain a mystery about the universe’s expansion rate.

Astronomers tallying up all the normal matter—stars, galaxies and gas—in the universe today have come up embarrassingly short ...

In the grand puzzle of the cosmos, one question continues to defy easy answers: how fast is the universe expanding?

One of the Holy Grails in cosmology is a look back at the earliest epochs of cosmic history. Unfortunately, the universe's first few hundred thousand years are shrouded in an impenetrable fog.

A new analysis of the sky has finally confirmed where the missing half of the Universe's visible matter has been hiding.