Meteors and showers a millennium ago

Abstract

Meteors can be classified into either sporadic meteors or showery meteors. We compile the meteor records in the astronomical archives in the chronicle of the Koryo dynasty (918-1392), and investigate the spatial distribution of meteor streams along the orbit of the Earth from the 10th to the 14th century. We see that meteors from meteor streams signalize themselves over noisy sporadic meteors, and that the seasonal activity of sporadic meteors is apparently regular. We discover the presence of a few meteor streams by analysing about 700 meteors in the Koryo period. We also compile the records of meteor showers and storms in the chronicles of Korea, Japan, China, Arabia and Europe, and compare their appearance dates with those of showers obtained in our analysis, as well as with the modern observations. We confirm that the three sets of data are in agreement with each other. The representative meteor showers are the Perseids, the Leonids, and the η Aquarids/Orionids pair formed by Halley's comet. The other weak or relic meteor streams are also observable but uncertain. Hence we witness the regularity of meteor activity, which is seen to persist for a millennium.