Since the position of the Moon is very well known for any given time, that meant he could nail down the location of 3C273.The linear feature to the upper left is a jet of material accelerated by the quasars black hole central engine.If Im writing about a black hole, say, then it helps to link to older articles that have background info, saving me the trouble of writing it again.Meaning, I havent written about this particular object before.
Thats fine; I cant write about everything, but whats weird is when its about some famous or particularly iconic astronomical object. A few years ago, for example, I was looking for stuff I had written about Proxima Centauri, the closest star to the Sun, and discovered I had never written an article devoted to it That was weird, and now happily fixed ( many times over ). ![]() But, due to space requirements, I had to leave most of the story out. But now I can remedy that It took a lot of editing to make it a standalone article, but here you go: How we found out that not every galaxy is as clement as the Milky Way. To the best of my knowledge at the time, what I wrote was correct. But not long after posting this article I got a note from an astronomer saying Milton Humason and his team had actually found objects with higher redshifts (and are therefore further away from us) years before this in 1956 I never found this paper in my research, obviously. While Im delighted to learn something new, this does cast a different light on some of the aspects of the story, like Schmidts confusion on the spectrum. ![]() Radio astronomy was coming into its own, and huge dishes were scanning the heavens looking for cosmic objects that emitted radio waves. Cambridge University sponsored several such surveys, numbering them 1C through 5C. In the third catalog called, surprise, 3C was an object in the constellation of Virgo. It was fairly bright in radio, and variable, too its brightness fluctuated on a scale of days. But while the radio telescope used to make the surveys was sensitive, its eyesight was somewhat fuzzy, and an exact location for 3C273 was impossible to determine (this same situation was faced just a few years later by astronomers observing gamma-ray bursts ). Without an exact location, it wasnt possible to look for the object using optical telescopes and find out if it were a star, a galaxy, or some more exotic object. Astronomy Redshift Full Of StarsThe sky is full of stars, and thousands of objects were within the uncertainty of 3C273s location. Now be honest: If it werent arrowed youd never have noticed it, would you Credit: SDSS Aladin. Virgo is a constellation on the zodiac, which means that the Sun and planets appear to move through it and so does the Moon. Hazard discovered that in 1962 the Moon would pass directly over the most likely position for 3C273. What Hazard realized is that he could point a radio telescope at the radio source, then wait for the Moon to cover it (what astronomers call an occultation ). At that moment the radio emission would cease, and he could measure that exact time.
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