Page "SN 1054" Paragraph 85

If all the available elements strongly suggest that the star of 1054 was a supernova, and that in the area next to where the star was seen, there is a remnant of a supernova which has all of the characteristics expected of an object that is around 1000 years old, a major problem arises: the new star is described as being to the South-East of Tianguan, while the Crab Nebula is to the North-East.

This problem has been known since the 1940s and has long been unsolved.

In 1972 for example, Ho Peng Yoke and his colleagues suggested that the Crab Nebula was not the product of the explosion of 1054, but that the true remnant was to the South-East, as indicated in several Chinese sources.

For this, they envisaged that the angular unit cun corresponds to a considerable angle of 1 or 2 degrees, meaning that the distance from the remnant to ζ Tauri was therefore considerable.

Aside from the fact that this theory does not account for the large angular sizes of certain comets, expressed in zhang, it comes up against the fact that there it does not make sense to measure the gap between a guest star and a star located so far away from it, when there are closer asterisms that could be used.