In the “Lord of the Rings” series, Lord Sauron, depicted by the “Eye of Sauron” sought the sole remaining ring through which he could rule all of Middle Earth. Well, he may yet succeed after all – at least in galactic terms. This is because the galaxy known formally in the astronomical catalog as NGC 4151 will now become a cosmic distance marker from which other distances will be ruled. In a report published in the highly regarded scientific journal Nature, researchers from the Niels Bohr Institute in Denmark and the University of Southampton were able to accurately measure the distance of the “Eye of Sauron” galaxy from the earth at 62 million light years. Prior estimates pegged the distance at anywhere from 13 to 95 million light years away. Now that the galaxy’s distance is accurately established, it can be used to calibrate measurements used to determine distances to other plants and galaxies.
In the past, astronomers used redshift to determine the distance. This method involves measuring how wavelengths of light change as the light travels away from a source. In a manner of speaking, redshift is akin to the Doppler Effect for light as it travels through space. However, redshift has its limitations and gave wildly varying distances to NGC 4151. Researchers used interferometry to accurately determine the “Eye of Sauron” galaxy’s distance from earth at 62 million light years. This method involved using the two telescopes at the W. M. Keck Observatory in Hawaii. Their method involved combining the two 10m mirrors to observe light patterns with the effective resolution of an 85m mirror. The resulting resolution was two full orders of magnitude greater than that of the Hubble telescope. Now, interferometry will be used to accurately determine the distances to other stars and galaxies, but also help establish additional cosmic distance markers.
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