The Sloan Great Wall: Largest Known Structure
7.11.2007

What is the largest structure known? The answer might depend on how one defines "structure." A grouping of galaxies known as the Sloan Great Wall was discovered in the Sloan Digital Sky Survey and is a leading candidate.

A Note on the Perseus Cluster
12.09.2003

A truly enormous collection of thousands of galaxies, the Perseus Cluster - like other large galaxy clusters - is filled with hot, x-ray emitting gas. The x-ray hot gas (not the individual galaxies) appears in the left panel above, a false color image from the Chandra Observatory.

Abell 3827: Cannibal Cluster Gravitational Lens
23.08.2021

Is that one galaxy or three? Toward the right of the featured Hubble image of the massive galaxy cluster Abell 3827 is what appears to be a most unusual galaxy -- curved and with three centers.

Looking Through Abell 68
8.03.2013

Want to use a cluster of galaxies as a telescope? It's easier than you might think as distant galaxy clusters naturally act as strong gravitional lenses. In accordance with Einstein's theory...

Fortuitous Flash Candidate for the Farthest Star Yet Seen
11.04.2018

Was this flash the farthest star yet seen? An unexpected flash of light noticed fortuitously on Hubble Space Telescope images may prove to be not only an unusual gravitational lensing event but also an image of a normal star 100 times farther away than any star previously imaged individually.

M86 in the Central Virgo Cluster
14.08.2018

Is there a bridge of gas connecting these two great galaxies? Quite possibly, but it is hard to be sure. M86 on the upper left is a giant elliptical galaxy near the center of the nearby Virgo Cluster of galaxies.

Earendel: A Star in the Early Universe
6.04.2022

Is Earendel the farthest star yet discovered? This scientific possibility started when the Hubble Space Telescope observed a huge cluster of galaxies. The gravitational lens effectбof this cluster was seen to magnify and distort a galaxy far in the background.

APOD: 2025 October 7 Б SN Encore: A Second Supernova Seen Several Times
7.10.2025

Now a second supernova in this same galaxy is repeating. The cause is the gravitational lens effect of a massive foreground cluster of galaxies (MACS J0138) -- it creates multiple images of a perfectly aligned background galaxy (MRG-M0138). What's particularly interesting is that this background galaxy has young stars that keep blowing up.

Dark Matter Map
14.08.2003

The total mass within giant galaxy cluster CL0025+1654, about 4.5 billion light-years away, produces a cosmic gravitational lens -- bending light as predicted by Einstein's theory of gravity and forming detectable images of even more distant background galaxies.

The Virgo Cluster: Hot Plasma and Dark Matter
19.04.1996

This ROSAT image of the Virgo cluster of galaxies reveals a hot X-ray emitting plasma or gas with a temperature of 10-100 million degrees pervading the cluster. False colors have been used to represent the intensity of X-ray emission.