Astronomy

Discovery of the Crab Nebula



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Astronomy and the discovery of new celestial objects can be an unfair business. Sometimes astronomers discover new, fascinating objects, but somehow these discoveries are forgotten, or fellow astronomers carry away the fame.

This is the case with the discovery of the Crab Nebula. For actually, this nebula was discovered, described, forgotten, and rediscovered several times during its approximately 950 years of existence. That is, its existence as seen from Earth. For the Crab Nebula is a remnant of a star-explosion or supernova that took place over 4000 years ago.

First discoveries

According to extensive research of old astronomical documents, this supernova may have been observed and described as early as 1054. Chinese and Arab sources independently mention a new star in the sky in that year. This star was visible for at least a month, but possibly even a few years, as it first intensified in brightness and then diminished. At its brightest, it could be seen during the day while at night it was nearly as bright as the moon. But as is so often the case in ancient or old documents, the sources do not mention the names of the Chinese nor those of the Arab astronomers, who witnessed and documented this event.

Rediscoveries

As its brightness diminished, its existence was also forgotten. That is, until 1731, when a keen English amateur astronomer called John Bevis (re)discovered the object. He included it in his atlas of objects in the sky, which he called Uranographia Britannica.

John Bevis may be the first in Western Europe to describe the object. It is also described in an astronomical catalogue on nebulae and other interesting objects, by the French astronomer Charles Messier. He (re)discovered the object in 1758 and in his catalogue it received the notation M1. This is still the name used to describe the Crab Nebula: Messier 1 or M1.

Crab Nebula

The name Crab Nebula was given to M1 by another English astronomer, the third Earl of Rosse. He built a large telescope while living at his inherited castle in Ireland and started to use this telescope in 1847. He not only observed objects with it, but also drew them. His first drawing of the nebula reminded him of a crab and hence the name Crab Nebula. A better telescope enabled the Earl to improve his observations and drawings, but the name stuck.

Conclusion

So, actually there is no single name linked to the discovery, rediscovery and naming of the Crab Nebula. The books of course mention John Bevis, in 1731. However, his name should not be mentioned without also acknowledging that the anonymous Chinese and Arab astronomers actually witnessed its "birth" first!

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