A MACHO View of Galactic Dark Matter
1.02.1996

What is our Galaxy made of? Stellar motions indicate there is much more mass than just stars and gas. Photographs like the two shown above may be yielding a clue about the dark matter, however.

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.

SDSSJ1430: A Galaxy Einstein Ring
28.07.2008

What's large and blue and can wrap itself around an entire galaxy? A gravitational lens mirage. Pictured above on the left, the gravity of a normal white galaxy has gravitationally distorted the light from a much more distant blue galaxy.

Distortion from a Distant Cluster
23.08.2001

This stunning color deep sky view toward the constellation Pisces was made with data from a fast, sensitive, digital detector known as the Big Throughput Camera operating at Cerro Tololo Inter-American Observatory in Chile.

APOD: 2025 October 7 Б SN Encore: A Second Supernova Seen Several Times
6.10.2025

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.

Fortuitous Flash Candidate for the Farthest Star Yet Seen
10.04.2018

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.

A Blue Bridge of Stars between Cluster Galaxies
15.07.2014

Why is there a blue bridge of stars across the center of this galaxy cluster? First and foremost the cluster, designated SDSS J1531+3414, contains many large yellow elliptical galaxies. The cluster's center...

Galaxy Einstein Ring
19.04.2016

Can one galaxy hide behind another? Not in the case of SDP.81. Here the foreground galaxy, shown in blue in an image taken by the Hubble Space Telescope, acts like a huge gravitational...

The El Gordo Massive Galaxy Cluster
22.04.2014

It is bigger than a bread box. In fact, it is much bigger than all bread boxes put together. Galaxy cluster ACT-CL J0102-4915 is one of the largest and most massive objects known. Dubbed...

Galaxy Cluster Abell 370 and Beyond
11.09.2023

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.