The Cosmic Infrared Background
5.02.2002

What cosmic wallpaper is on the sky? The answer depends on the type of light considered, and for some wavelengths, all the cluttering material in the foreground makes it still unknown. Recently, however...

Chandra Resolves the Hard X Ray Background
13.01.2000

It is everywhere but nobody knew why. In every direction at all times, the sky glows in X-rays. The X-ray background phenomenon was discovered over 35 years ago, soon after the first X-ray satellites were launched, and has since gone unexplained.

A Year of Resolving Backgrounds
29.12.2000

No matter which direction you look, no matter what type of light you see, the sky glows - but why? The sources of many of these background radiations have remained long-standing puzzles, but this millennial year brought some partial resolutions.

Universe Age from the Microwave Background
16.02.2003

The above sky map tells us the universe is 13.7 billion years old -- but how? At first look, one only sees the microwave glow of gas from our Milky Way Galaxy, coded red, and a spotty pattern of microwaves emitted from the early universe, coded in gray.

Planck Maps the Microwave Background
21.07.2018

What is our universe made of? To help find out, ESA launched the Planck satellite from 2009 to 2013 to map, in unprecedented detail, slight temperature differences on the oldest optical surface known -- the background sky when our universe first became transparent to light.

Planck Maps the Microwave Background
25.03.2013

What is our universe made of? To help find out, ESA launched the Planck satellite to map, in unprecedented detail, slight temperature differences on the oldest surface known -- the background sky left billions of years ago when our universe first became transparent to light.

Galaxy Cluster Gas Creates Hole in Microwave Background
9.04.2017

Why would this cluster of galaxy punch a hole in the cosmic microwave background (CMB)? First, the famous CMB was created by cooling gas in the early universe and flies right through most gas and dust in the universe. It is all around us.

The Cosmic X-Ray Background
8.11.2000

Early on, x-ray satellites revealed a surprising cosmic background glow of x-rays and astronomers have struggled to understand its origin. Now, peering through a hole in the obscuring gas and dust...

The Milky Way's Center
8.09.1995

NASA's COBE satellite scanned the heavens at infrared wavelengths in 1990 and produced this premier view of the central region of our own Milky Way Galaxy. The Milky Way is a typical spiral galaxy with a central bulge and extended disk of stars.

A Gallery of Gravitational Mirages
1.06.1999

The deeper you peer into the universe, the harder it is to see straight. The reason is that distant galaxies act as gravitational lenses, deflecting light that passes nearby. These deflections result in the distortion of background sources, and in some cases the creation of multiple images.