Little Bits of History

July 4

Posted in History by patriciahysell on July 4, 2017

1054: A “guest star” is first noticed in China. In Chinese astronomy, the term refers to a star which appears suddenly where no star had been before and then, after some time, disappears. These are novas or supernovas. In ancient times, context is needed to determine if the guest star is one of the catastrophic events or a comet with or without a tail. Extant Chinese records come from at least two sources. There are other worldwide references to what is now known as SN 1054 coming from questionable sources in European works and more substantial records of Ancestral Puebloan culture found in New Mexico, United States. The remnant of the explosion of the star once located in the sky near Zeta Tauri is called the Crab Nebula.

There are eight known supernovas in the Milky Way, identified because of existing testimony of the time. The old Chinese texts show the appearance of a guest star during the reign of Emperor Renzong of the Song dynasty. By studying the writings and correlating known historical events, it was found to be on this day. Writings of the event are included in both Song Shi and Song Huiyao, both texts about the history of the Song dynasty. They describe the sudden appearance of new star near Zeta Tauri which remained visible for a total of 642 days, with the star bright enough to be visible even during the daylight hours for 23 of those days.

The Crab Nebula (M1, Messier 1, NGC 1952, Taurus A, Sh2-244) was the first astronomical object identified with a historical supernova explosion. The Nebula is not visible to the naked eye but can be seen even with binoculars (under favorable conditions). The nebula was first identified in 1731 but to little fanfare. Charles Messier was studying a comet in 1758 and found the nebula again. Although officially cataloged, nothing else was known of it. With spectroscopy, the artifact was again found in 1913 and several photos taken years apart revealed the nebula was expanding. Discovering the relationship between SN 1054 and the Nebula began in 1921.

Edwin Hubble proposed a controversial idea – the nebula was the debris of the 1054 supernova. Knowing as much about astronomical events as we now do, it is currently thought the supernova actually took place in April or early May and was bright enough to finally be discovered in July. The Crab Pulsar was the cause for more study of the Crab Nebula. Because of early recordings, the date of the event and the data collected gave astronomers a greater understanding of the highly magnetized, rotating neutron star or white dwarf. While we know much about the nebula, we are still uncertain about several details. Watching the night sky still allows us to learn much about the universe in which we live.

Astronomy? Impossible to understand and madness to investigate. – Sophocles

Astronomy, as nothing else can do, teaches men humility. – Arthur C Clarke

The universe seems neither benign nor hostile, merely indifferent. – Carl Sagan

Astronomy’s much more fun when you’re not an astronomer. – Brian May

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