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.
What is a Comet?
Did our Ancestors consider Comets to be Gods?
We haven't lost our ancient ancestors' observations of comets. We foolishly dismissed their descriptions and cataclysmic stories as myth—as fiction or moral cautionary tales. They lacked the word komete (comet), a word coined by Aristotle in the 4th century BCE, but their descriptions of the approach of a god or monster, and its impact on Earth, are detailed and haunting. It's obvious after reading these "myths", comparing them to others, and speaking to scientists, that our ancestors witnessed comet impacts and frightening near misses.
Don't we owe it to our ancestors, who struggled to survive in the wake of these celestial cataclysms, a progressive world, in which we use science and comparative religion to search for the truth? With the help of religious scholars, anthropologists, and astrophysicists from the Jet Propulsion Laboratory and NASA, the author of Fall of a Thousand Suns spent years exploring what our ancestors experienced and when they experienced it. That journey into the past is detailed in Fall of a Thousand Suns: How Near Misses and Comet Impacts affected the Religious Beliefs of our Ancestors.
- Did our Ancestors consider Comets to be Gods and Monsters?
- The First Recorded Comet Observation
- The Greeks - Aristotle's Understanding of Comets
- The Enlightenment - Apian, Copernicus, Newton and Halley
- Where do Comets Come From?
- What are Comets Made of?
The First Recorded Comet Observation
Although comets have been in the skies for 4.6 billion years, including the blip of time we know as human history, the first definitive mention of comets doesn't come until the following sentence was written, "When Chieh executed his faithful counselors, a comet appeared."
According to Carl Sagan and Anne Druyan in Comet: Revised, the above sentence referred to a time the fifteenth century BCE. However, Chieh was the last ruler of the Xia dynasty. Traditional chronology has the Xia Dynasty ending in 1766 BCE. Chronology in The Bamboo Annals allude to the dynasty ending in 1558 BCE. The Xia-Shang-Zhou Chronology Project has it ending in 1600 BCE.
Between 1600 BCE and 100 CE, the Chinese recorded at least 338 observations of comets (Sagan, Druyan). They also began to track and record the movement of comets, stripping them of some of their religious significance as gods or monsters.
Chinese astronomers referred to comets by thirty-five different names, including "hui".
The Greeks - Aristotle's Understanding of Comets
Aristotle (384-322 BCE) shot down these early theories, in favor of his own. The night sky moved with predictable, clocklike precision. So, in Aristotle's mind, the unpredictable appearance and movement of comets meant they had to come from Earth. He reasoned that the Sun's heat caused hot, flammable air to rise high above Earth, where it ignited and became a fiery comet.
Ephorus of Cyme (405-330 BCE) has one of the ealiest indisputable observations of a comet fragmentation. He wrote that the comet of 371 BCE "split into two stars." Fall of a Thousand Suns examines much older ancient myths and beliefs, suggesting they are observations of comet fragmentaion that predate Ephorus of Cyme's observation by centuries or millenia.
The Enlightenment - Apian, Copernicus, Newton and Halley
In the western world, Aristotle's theory on the origin of comets was fairly popular until the sixteenth century, when a German astronomer named Peter Apian observed that a comet tail always pointed away from the Sun. In Questions Naturales, Seneca (4 BCE - 65 CE) had observed this fact as well writing "[the tails of a comet] fly from the Sun's rays." His words, and observation, had largely been forgotten.
A few years after Apian's observation, astronomer Tycho Brahe charted a comet against the stars night after night—and claimed it was, at least, four times further away than the Moon. Aristotle was wrong. But if comets weren't emissions from Earth, then what were they?
A revolution in the understanding of comets, and even the nature of the solar system, was in full swing. In 1543, Copernicus advanced the then-revolutionary idea that all planets, including Earth, revolved around the Sun.
In 1680, several astronomers carefully tracked a spectacularly bright comet through the constellations. Isaac Newton used these calculations to prove that comets traveled in elliptical orbits and were affected by the gravity of planets and the Sun.
Newton's friend, astronomer Edmond Halley, chimed in. Halley believed that comets observed in 1456, 1531, 1607, and 1682 were really a single comet orbiting through our solar system. Halley predicted it would return in early 1759. When the comet was spotted on Christmas Eve in 1758, it became known as Halley's Comet. Its return appearance proved that comets weren't unpredictable; they were orbiting the Sun just like planets.
Where do Comets Come From?
With great minds like Newton's and Halley's contributing to our ever-evolving understanding of comets, debate raged over the next big question. Where did comets come from? Eighteenth and nineteenth century astronomers spotted most comets, for the first time, near the Sun or a planet, but occasionally in areas of space nowhere near either. Since comets were now known to be objects that orbited the Sun, astronomers realized by extrapolating their orbits that they must come from somewhere in deep space far beyond the orbit of Neptune...but where? How?
Exploded view of thousands of objects in the Kuiper Belt surrounded by hundreds of billions of comet nuclei in the Oort Cloud.
Credit: Don Yeomans/NASA/JPL illustration adapted by Kevin Curran
It wasn't until World War II that Irish astronomer Kenneth Edgeworth theorized that a sphere of thousands of icy objects was beyond the orbit of Neptune. These icy objects were formed around 4.5 billion years ago along with the rest of our solar system. Occasionally, one of the icy objects was knocked from its stable orbit and entered the inner solar system, where it developed a coma and tail. This theoretical sphere of icy objects became known as the Kuiper Belt.
The Kuiper Belt contains thousands of comets-in-waiting, but what if I told you there were also hundreds of thousands of asteroids in our solar system, and a sphere of hundreds of billions of comets beyond the Kuiper Belt? Would you learn to live off the land and watch marathons of Doomsday Preppers in your underwear until your spouse divorces you? If so,
you can start planting your vegetable garden. Beyond the Kuiper Belt lies the Oort Cloud, a theoretical sphere of hundreds of billions of comets. That's not a typo. Between one hundred billion and two trillion icy objects are thought to exist between 1,000 and 100,000 AU from the Sun.
What are comets made of?
Comets are made of rock, dust, ice, methanol, hydrogen cyanide, formaldehyde, ethanol, ethane, hydrocarbons and a variety of frozen gases including carbon dioxide, methane, carbon monoxide and ammonia. Like each planet in our solar system, each individual comet contains different chemicals in varying amounts. They are often referred to as "dirty snowballs", but actually contain a hard crust on the exterior.
Nucleus of Comet Tempel 1 (9P/Tempel)
Credit: NASA / Deep Impact Spacecraft
Various spacecraft have attempted to determine the composition of comets: These spacecraft include various ones sent by Russia, ESA, Japan and NASA to study Halley's Comet during its apparition in 1986. ESA's Giotto actually came within 596 km of the nucleus. In 1999, NASA's Stardust collected dust samples from the coma of Comet Wild 2 and actually delivered them back to Earth.
On July 4, 2005, NASA's Deep Impact successfully hit the nucleus of Comet 9P/Tempel. For once we left a crater on a comet, instead of the other way around. Beginning in August of 2014, the European Space Agency's Rosetta Spacecraft will catch-up with Comet 67P/Churyumov-Gerasimenko, while it is still is in the colder regions of our solar system at a distance of 3.5 AU from the Sun. Rosetta will then deploy a 100-kilogram lander, named Philae, which will attach to the comet's surface. The lander will collect chemicals before, during and after its perihelion on August 13, 2015. The composition of the comet can then be analyzed back on Earth. "It's risky, because nobody has done that before, but this is the price to pay to learn about the origin of the solar system and perhaps more of the origin of life," said ESA Director General Jean-Jacques Dordain.
- List of Non-Periodic Comets
- List of Periodic Comets
- Comets in 2013
- Comets in 2014
- Comets in 2015
- Comets in 2016
- Comets in 2017
- Brightest Comets in 20th Century
- Brightest Comets in 21st Century
- Brightest Comets in History
- Parts of a Comet
- How does a comet get its name?
- What is a Meteor Shower?