News Release Archive:

News Release 10 of 34

September 9, 2009 11:00 AM (EDT)

News Release Number: STScI-2009-25

Hubble Opens New Eyes on the Universe


Image: Gravitational Lensing in Galaxy Cluster Abell 370

Gravitational Lensing in Galaxy Cluster Abell 370STScI-PRC2009-25h

Screen-use options: These files are created for viewing on your monitor

Print-use download options: These files are designed to fit on letter-size paper

Highest-quality download options
The best resolution available can be found here.


Hubble Space Telescope's newly repaired Advanced Camera for Surveys (ACS) has peered nearly 5 billion light-years away to resolve intricate details in the galaxy cluster Abell 370.

Abell 370 is one of the very first galaxy clusters where astronomers observed the phenomenon of gravitational lensing, where the warping of space by the cluster's gravitational field distorts the light from galaxies lying far behind it. This is manifested as arcs and streaks in the picture, which are the stretched images of background galaxies.

Gravitational lensing proves a vital tool for astronomers when measuring the dark matter distribution in massive clusters, since the mass distribution can be reconstructed from its gravitational effects.

Ground-based telescopic observations in the mid-1980s of the most prominent arc (near the right-hand side of the picture) allowed astronomers to deduce that the arc was not a structure of some kind within the cluster, but the gravitationally lensed image of an object two times farther away. Hubble resolves unseen new details in the arc that reveal structure in the lensed background galaxy.

Galaxy clusters are the most massive structures of the universe, located at the crossing of the filaments of the cosmic web of dark matter. The most massive clusters can contain up to 1,000 galaxies and intergalactic hot gas, all held together primarily by the gravity of dark matter.

These observations were taken with Hubble's Advanced Camera for Surveys (ACS) in its Wide Field mode on July 16, 2009. The composite image was made using filters that isolate light from green, red, and infrared wavelengths.

These Hubble data are part of the Hubble Servicing Mission 4 Early Release Observations.

Object Name: Abell 370

Image Type: Astronomical

Credit: NASA, ESA, the Hubble SM4 ERO Team, and ST-ECF

Technical facts about this image:

About this Object
Object Name: Abell 370
Object Description: Cluster of Galaxies
Position (J2000): R.A. 02h 39m 49s.90
Dec. -01° 34' 26".70
Constellation: Cetus
Distance: 4.9 billion light-years (1.5 billion parsecs)
Dimensions: This image is 2.4 arcminutes (3.4 million light-years or 1 million parsecs) wide.
About these Data
Data Description: The Hubble images were created from data from proposal 11507: K. Noll (STScI), M. Chiaberge (STScI/ESA/INAF), M. Mutchler, D. Golimowski, and R. Lucas (STScI), and M. Sirianni (STScI/ESA).
Instrument: ACS/WFC
Exposure Date(s): July 16, 2009
Exposure Time: 3.5 hours
Filters: F475W (g), F625W (r), and F814W (I)
About this Image
Credit: NASA, ESA, the Hubble SM4 ERO Team, and ST-ECF
Release Date: September 9, 2009
Color: The image is a composite of separate exposures made by the ACS instrument on the Hubble Space Telescope. Three filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are:
F814W (I) red
F625W (r) green
F475W (g) blue
Orientation/Scale: Gravitational Lensing in Galaxy Cluster Abell 370
Acknowledgments for Abell 370
Observers: K. Noll (STScI), M. Chiaberge (STScI/ESA/INAF), M. Mutchler, D. Golimowski, and R. Lucas (STScI), and M. Sirianni (STScI/ESA)
Data Analysis: M. Mutchler (STScI) and R. Hook (ST-ECF)
Image Composition: R. Hook, O. Hainaut, A. Bombik, and L. Christensen (ST-ECF), Z. Levay and L. Frattare (STScI)
Text: L. Frattare, D. Weaver, and R. Villard (STScI) and C. Sharkey and M. Lombardi (ST-ECF)
Illustrations: Z. Levay (STScI)
Video: G. Bacon (STScI)
Science Consultants: M. Livio and B. Whitmore (STScI) and J.-P. Kneib (Observatoire Midi-Pyrenées)


The above montage includes these images:

Gravitational Lens Detail in Abell 370 Image Type: Astronomical Gravitational Lens Detail in Abell 370 Details of the Hubble Abell 370 Image Image Type: Astronomical Details of the Hubble Abell 370 Image

All images from this news release:

To access available information and downloadable versions of images in this news release, click on any of the images below: