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The universe is eerie enough without giving us an apparition of a 1980s
video game alien attacker. This oddball-looking object is really a mirage
created by the gravitational field of a foreground cluster of galaxies
warping space and distorting the background images of more distant
This effect, called gravitational lensing, can make multiple mirror image
copies of the light coming from a far-flung galaxy. It is a powerful tool
for seeing remote galaxies that otherwise would not be observable by
Hubble because they are too dim and far away. In this Hubble photo a
background spiral galaxy is warped into an image that resembles a
cartoon of a simulated space invader. The foreground massive cluster, called Abell 68, lies 2 billion light-years
away. The brightened and stretched lensed images come from galaxies
far behind it.
The gravitational field surrounding this massive cluster of galaxies,
Abell 68, acts as a natural lens in space to brighten and magnify the
light coming from very distant background galaxies.
Like a funhouse mirror, lensing creates a fantasy landscape of
arc-like images and mirror images of background galaxies. The
foreground cluster is 2 billion light-years away, and the lensed images
come from galaxies far behind it.
In this photo, the image of a spiral galaxy at upper left has been
stretched and mirrored into a shape similar to that of a simulated
alien from the classic 1970s computer game Space Invaders! A second,
less distorted image of the same galaxy appears to the left of the
large, bright elliptical galaxy.
In the upper right of the photo is another striking feature of the
image that is unrelated to gravitational lensing. What appears to be
purple liquid dripping from a galaxy is a phenomenon called
ram-pressure stripping. The gas clouds within the galaxy are being
stripped out and heated up as the galaxy passes through a region of
denser intergalactic gas.
This image was taken in infrared light by Hubble's Wide Field Camera
3, and combined with near-infrared observations from Hubble's Advanced
Camera for Surveys.
The image is based in part on data spotted by Nick Rose in the Hubble's Hidden Treasures image processing competition.
For additional information, contact:
Space Telescope Science Institute, Baltimore, Md.