A Gravitational Lens Shows the Same Galaxy Three Times
Images from the Hubble Space Telescope are often mind-bending in both their beauty and wealth of scientific wonder. And sometimes, Hubble captures light-bending images too.
Hubble’s Wide Field Camera 3 (WFC3) snapped a photo of a galaxy where the light has been bent by gravitational lensing, so that the galaxy show up not just once, but three times. But the multiple views aren’t exact replicas of each other — they appear as different shapes.
Take a look at the clumps of light in the bottom right corner of the image. The galaxy, with a license-plate-like name of SGAS 0033+02, appears once as a curved arc and twice more as small round dots around the bright star.
Why does it look this way? Gravitational lenses occur when a massive object, such as a galaxy, is aligned directly between Earth and another massive object even farther away. Einstein predicted that gravity could bend light, and this image is a wonderful example of how gravity from foreground objects causes a deflection of light from background objects.
In this case, SGAS 0033+02 is curved (or ‘lensed’) by the gravity of a massive celestial object that lies in the foreground, between the distant galaxy and the Earth. The Hubble team says that SGAS 0033+02 is of special interest because of its highly unusual proximity in the sky to a very bright star. The star is useful, because it can be used to calibrate and correct observations of the lensed galaxy.
SGAS 0033+02 is so named because it was discovered the Sloan Giant Arcs Survey (SGAS), which searches for and identifies highly magnified galaxies that were gravitationally lensed by foreground galaxy clusters.
Other lensed galaxies are visible in this image as well. This picture is also interesting because it appears to hold more galaxies than stars.
Also, in other Hubble news, the engineers and scientists of Hubble continue to bringing the venerable space telescope back to normal science operations following a glitch that put the entire telescope in ‘safe mode’ on October 23, 2021. All of the science instruments were offline and unavailable for observations. The underlying cause appeared to be a “synchronization error” which means the instruments could not sync up to collect data properly. Engineers were able to bring one instrument, the Advanced Camera for Surveys (ACS), back online in early November, and now recovered the Wide Field Camera 3 instrument as of November 21.
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