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Hubble uses cosmic optical illusion to spy a quasar 17 billion light-years away

This week’s image from the Hubble Space Telescope shows a kind of optical illusion that is helping researchers to peer out even deeper into the depths of our universe. Using a phenomenon called gravitational lensing, Hubble captured this image which seems to show four bright points of galaxies forming a ring around an even brighter central pair.

But despite how it appears, there aren’t six galaxies represented in the center of this image — there are actually two galaxies and one very, very distant quasar, which is an extremely bright center of a galaxy.

Clustered at the center of this image are six brilliant spots of light, four of them creating a circle around a central pair. It is not two separate galaxies and one distant quasar imaged four times.
Clustered at the center of this image are six brilliant spots of light, four of them creating a circle around a central pair. Appearances can be deceiving, however, as this formation is not composed of six individual galaxies, but is actually two separate galaxies and one distant quasar imaged four times. ESA/Hubble & NASA, T. Treu; Acknowledgment: J. Schmidt

This effect happens because the two galaxies, which are closer to us, act like a magnifying glass on the quasar called 2M1310-1714, which is farther away at approximately 17 billion light-years distance from us. The galaxies have so much mass that their gravity bends the rays of light coming from the quasar, making the quasar more clearly visible to us.

It is this bending that makes it appear that there are four points of light surrounding the pair of galaxies when in reality there is actually just one quasar, the light from which is warped to make it look like four light sources.

Gravitational lensing may be visually confusing, but it can be a powerful tool for examining distant objects. It allows researchers to see farther out and could even be used to study the mysterious phenomenon of dark matter. A variation on this technique, called microlensing, will be used by the upcoming Nancy Grace Roman Space Telescope to detect distant exoplanets by seeing the way light bends when one star passes in front of another.

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Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
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