1705: Halley’s comet - The book of science

Halley’s comet
Apparitions
Perturbations
Commentary

Halley’s comet

Edmond Halley was interested in proving
Kepler’s laws of planetary motion.
He went to Cambridge to discuss this with Isaac Newton,
only to find that Newton had already formulated
his laws of motion and universal gravitation
and derived Kepler’s laws from these.
Halley paid to publish Newton’s Philosophiæ
Naturalis Principia Mathematica
and began to apply Newton’s laws to explain
the effects of Jupiter and Saturn
on the orbits of comets, and to connect
historical observations.
Since 240 BCEE, Chinese, Babylonian,
and medieval European astronomers
recorded the appearance of comets,
but separate observations
were not connected to the same object.
In 1705, in his Synopsis of the Astronomy of Comets,
Halley connected Petrus Apianus’ observation in 1531
and Johannes Kepler’s observation in 1607
with the second comet observed in 1682
and predicted its return after 76 years.
When it returned as predicted
it was named after him.

Apparitions

Appearances of Halley’s comet since 240 BCEE
were chronicled by the Chinese
who called it the broom star.
In 164 BCEE, in Babylon, Halley’s comet
was recorded in cuneiform on a clay tablet
now in the British Museum.
The Annals of Ulster noted in 912,
“A dark and rainy year.
A comet appeared.”
In an English woodcut from 1531, Halley’s comet
appears as a series of yellow fuzzballs
with thick brown straw-like tails.
The Bayeux Tapestry depicts the appearance of Halley’s comet
in 1066 as a spiky brown ball
at the head of a rake with streamers.
The appearance in 1066 was also described
in the Anglo-Saxon Chronicle by Eilmer of Malmesbury
and the Irish Annals of the Four Masters.
In 1470 the humanist scholar Bartolomeo Platina
wrote in his Lives of the Popes
of a “hairy and fiery star.”
Halley’s comet passed so close to the earth in 1910
that astronomer Camille Flammarion warned
cyanogen in the tail would poison all life.
Its only appearance during my lifetime was 1986
but it was far from the earth
and appeared on the other side of the sun.
If great things have passed me by
at least I can hope
I have tuned to the sounds of their passing.

Perturbations

The orbit of the comet is perturbed in passing by Jupiter, Saturn, Uranus, and Neptune.
A president is murdered; a war is lost; millions die of famine, hurricane, tsunami.
You are inspired by the music of a rock band; a loved one dies; you write a book.

Halley not only predicted the reappearance of the comet but in doing so helped banish superstition and ignorance regarding such unusual heavenly apparitions. In 1066 Eilmer of Malmesbury wrote, “I see you brandishing the downfall of my country. I hate you!” In 1470 Bartolomeo Platina wrote, “A hairy and fiery star having then made its appearance for several days, the mathematicians declared that there would follow grievous pestilence, dearth and some great calamity.” We might expect medieval monks to be susceptible to superstition, but not mathematicians. Even so, we are all human, and so in 1910 many bought anti-comet pills and anti-comet umbrellas to assuage their susceptibilities.