Recently, there have been many rare astronomical phenomena. Indeed, it will be hundreds of years before we can see Jupiter and Saturn so close to each other again. However, there are even stranger and more rare phenomena that can be observed in the night sky. However, to get a good look at them, you will need access to the NASA Hubble Space Telescope. As always, this amazing tool provides absolutely breathtaking images of distant galaxies, stars, and planets. The picture in front of you shows one of the rarest astronomical phenomena - "Einstein's ring". It's actually a distant galaxy curving through a cluster of galaxies. The reason for this phenomenon is a process called gravitational lensing. If a cosmic body, for example, the Sun was too massive, the effect of gravity would be so strong that the mass of the star could distort the space-time fabric and allow the light to bend.
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| Einstein's ring through the lens of the Hublle space telescope |
What are Einstein's rings?
Albert Einstein's General Theory of Relativity (GTR), published in 1916, predicted that massive objects such as stars could bend rays of light passing nearby; the gravitational attraction of various objects in the universe, in turn, occurs due to the fact that each object bends space.
Thus, the image of Einstein's ring, taken in the spring of 2018, illustrates graceful elliptical galaxies and impressive spirals observed in various positions: edge to the plane of the visible galaxy or "face to face", which the observer sees as magnificent spiral arms. In the photo below, you can see a monstrous collection of hundreds of galaxies chained together by the iron grip of gravity. The mass of this cluster is large enough to severely distort the spacetime around it, creating strange, winding curves that nearly surround the cluster's center.
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| A snapshot of an object named SDSS J0146-0929 was taken in April 2018 |
Interestingly, rings are created when light from distant objects, such as galaxies, passes an extremely large mass like this galaxy cluster. The Hubble image, published on the official NASA website, shows light from a galaxy that deflects and distorts around a massive intermediate galaxy cluster, and therefore is forced to travel along different light paths to Earth. This is why it seems that the galaxy is in several places at the same time.
A process called "gravitational lensing" allows astronomers to observe many distant galaxies and Einstein rings. To detect them, the observer, the gravitational lens, and the observed object must be located on the same straight line. It is in this case that the center of a distant galaxy is blurred along the edges of the lens and a luminous ring is formed. Such objects, according to NASA, are the best laboratories for studying galaxies, which are sometimes so small and distant that they can only be seen with the help of gravitational lensing.
"Molten ring" warps space and time
At the end of December 2020, representatives of the NASA space agency announced that light from galaxies in the center is bent in a curve that we see due to the gravity of the galaxy cluster lying in front of it. The close-to-perfect alignment of the background galaxies with the cluster's central elliptical galaxy, shown in the center of the Hubble image, distorted and enlarged the image of the background galaxy into an almost perfect ring. Further distortions are caused by the gravity of other galaxies in the cluster.
Note that for the Hubble telescope, which the James Webb Space Telescope is preparing to replace, the observation of the Einstein ring or "molten ring" is a huge success. The snapshot of the ring called GAL-CLUS-022058s once again confirms the correctness of Albert Einstein's hypothesis.
Interestingly, astronomers observed one of the best examples of Einstein rings in 2007. The object was near the luminous Red Galaxy LRG 3-757. Because of its horseshoe shape, the photograph was unofficially called the cosmic horseshoe.
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| Einstein's Ring near the Red Galaxy LRG 3-757 as viewed by the Hubble Space Telescope |
Blue light is also clearly visible in the image. The reason the rings may appear blue is still debated in the scientific community because the gravitational lensing equation does not technically explain this effect. It was previously thought that blue originated from blue star-forming galaxies. However, a study published in 2011 proposed a theory for the diffraction of light waves in a gravitational field generated by the scattering of very low-frequency scalar waves in spacetime.
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