On the next clear night, go outside and look up. If you’re away from city lights, you may be amazed by the darkness of the sky between the stars. But what looks like inky black isn’t really so. Even ...

Galaxies in every corner of the universe have been sending out photons, or light particles, since nearly the beginning of time. Astronomers are now beginning to read this extragalactic background ...

A team of astronomers has detected a burst of very-high-energy gamma rays that was created over five billion years ago – the oldest such burst ever detected. On their journey to Earth, the gamma rays ...

Viewed in visible light, the sky appears as a dark expanse, adorned with the twinkling lights of faraway stars. But with an X-ray telescope, the sky seems uniformly bright, bathed in a diffuse glow.

Astronomers analyzing 13 years of data from NASA's Fermi Gamma-ray Space Telescope have found an unexpected and as yet unexplained feature outside of our galaxy. Astronomers analyzing 13 years of data ...

How much light has been emitted by all galaxies since the cosmos began? After all, almost every photon (particle of light) from ultraviolet to far-infrared wavelengths ever radiated by all galaxies ...

Researchers have just published the most precise analysis of the fluctuations in the gamma-ray background to date. By making use of more than six years of data, the researchers found two different ...