The Lyman Alpha Forest
12.11.2000

We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest.

The Gamma Ray Sky
12.01.2002

What if you could see gamma rays? If you could, the sky would seem to be filled with a shimmering high-energy glow from the most exotic and mysterious objects in the Universe.

JWST: Mirrors and Masked Men
12.03.2010

Who are these masked men? Technicians from Ball Aerospace and NASA at Marshall Space Flight Center's X-ray and Cryogenic Facility, of course, testing primary mirror segments of the James Webb Space Telescope (JWST).

The Universe in Hot Gas
20.08.2002

Where is most of the normal matter in the Universe? Recent observations from the Chandra X-ray Observatory confirm that it is in hot gas filaments strewn throughout the universe. "Normal matter" refers to known elements and familiar fundamental particles.

The Stars of NGC 1705
23.04.2003

Some 2,000 light-years across, NGC 1705 is small as galaxies go, similar to our Milky Way's own satellite galaxies, the Magellanic Clouds. At a much larger distance of 17 million light-years...

Pandora s Cluster of Galaxies
9.06.2023

This deep field mosaicked image presents a stunning view of galaxy cluster Abell 2744 from the James Webb Space Telescope's NIRCam. Also dubbed Pandora's Cluster, Abell 2744 itself appears to be a ponderous merger of three different massive galaxy clusters some 3.5 billion light-years away toward the constellation Sculptor.

Cosmology Solved?
4.11.1998

At the Nature of the Universe Debate held last month at the Smithsonian, top cosmologists P. James E. Peebles (Princeton) and Michael S. Turner (Chicago) argued over whether new data is finally resolving the type of universe in which we live.

Galaxy Cluster Abell 370 and Beyond
6.05.2017

Some 4 billion light-years away, massive galaxy cluster Abell 370 only appears to be dominated by two giant elliptical galaxies and infested with faint arcs in this sharp Hubble Space Telescope snapshot. The fainter...

Galaxy Cluster Abell 370 and Beyond
12.09.2023

Some 4 billion light-years away, massive galaxy cluster Abell 370 is captured in this sharp Hubble Space Telescope snapshot. The cluster of galaxies only appears to be dominated by two giant elliptical galaxies and infested with faint arcs.

Pandora's Cluster of Galaxies
8.06.2024

This deep field mosaicked image presents a stunning view of galaxy cluster Abell 2744 recorded by the James Webb Space Telescope's NIRCam. Also dubbed Pandora's Cluster, Abell 2744 itself appears to be a ponderous merger of three different massive galaxy clusters. It lies some 3.5 billion light-years away, toward the constellation Sculptor.