You can now buy the recently released book, Fall of a Thousand Suns: How Near Misses and Comet Impacts affected the Religious Beliefs of our Ancestors. It is available through iBooks and Amazon.
This website only lists information on modern-day comets and meteor showers. The book, however, thoroughly investigates how specific ancient impacts and near misses changed religious beliefs around the world.
Definition of Apparent Magnitude
Definition of Apparent Magnitude
Apparent magnitude is a standard measure used by astronomers to record the brightness of an object in space.
Initially it was developed by Ptolemy, an astronomer living in Egypt around 140 CE, simply to rank the brightness of stars visible to the naked eye. His scale went from 0 (the brightest star) to 6 (the faintest star). Since Ptolemy’s invention, negative numbers were added to allow the inclusion of the Sun, Moon, planets and comets. Each lower number represents an increase in brightness of two and a half times.
Example of Apparent Magnitude
The Great Comet of 1744 is a good example of how a comet can increase in brightness as it nears the Sun and sheds material. This shed material forms the comet's coma and tails.
November 29, 1743. The comet was first spotted and had an apparent magnitude of 4, which would make it barely visible in most cities today.
Mid-January. The comet's nucleus had brightened to a magnitude of 1 and it had grown a tail spanning 7° of the evening sky.
February 1. The tail covered 15° of sky and curved slightly as the comet began its tight turn around the Sun. The nucleus had more than quintupled in brightness, yet again, reaching an apparent magnitude of –1.5.
Mid-February. Within the next two weeks, the comet developed a second tail and grew as bright as Venus with a magnitude of –4.6.
February 27. It reached a maximum apparent brightness of –7. The Great Comet was now so bright that it was visible not only in the evening sky after the sun set, but it the daytime as it trailed the Sun by roughly twelve degrees.
Early March. The comet moved across the Sun and could not be seen for several days.
March 6th. The comet was spotted on the eastern horizon rising before the Sun. It now had six brilliant tails due to its incredibly tight orbit around the Sun at over 1,000,000 miles (1,609,344 km) an hour.
Each time this comet orbits the Sun it will shed material. Eventually, it will have nothing left to expel and become more like an asteroid with a dense, solid nucleus incapable of forming a coma or tail. The celestial "show" will be over.