Friday, March 13, 2009

Today in History: The Return of Halley's Comet

Edmund Halley, FRS (1656-1742)

It was 250 years ago today that Halley's Comet is recorded as having reached perihelion (i.e., closest distance to the sun) in its 1758-1759 return to the inner solar system. Of course, this comet has been orbiting the sun for eons. But what made this particular approach significant is that it had been predicted in advance by the English Astronomer Edmund Halley, in 1705.

Halley had been analyzing past comet sightings. He concluded that several observations of comets in the years 1456, 1531, 1607, and 1682, were actually appearances of the same comet, and he predicted that this periodic comet would re-appear in 1758. The comet did indeed appear on the 25th of December, 1758, and reached perihelion on the 13th of the following March. Henceforth, this comet became known as Halley's Comet.

Halley went on to succeed John Flamsteed as Astronomer Royal, in 1720. It is personally interesting to me, of course, that the Hawkins family undoubtedly observed Halley's comet in the winter of 1681-1682. Joseph Hawkins lived until October, 1682, leaving this world at the age of forty. The particular circumstances of his early demise are unknown, although a great many people died at relatively young ages in the early colonial settlements, compared to their contemporaries back in Europe (Halley himself lived to be 85, and Flamsteed lived to 73).

What I find profound about the comet is the manner in which it unites people across generations. I saw it myself in 1986. So did my parents. My father was alive, though very young, during its 1910 appearance. My mother had not been born yet. I doubt I will see its return in 2061 -- I'll be one hundred and one years old. But who knows? Maybe. Those of us who have experienced at least one lifetime sighting of Halley's Comet should consider ourselves to be very fortunate, indeed!

The nucleus of Halley's Comet, photographed by the European space probe Giotto, during the comet's 1986 fly-by.


Cassie said...

Wow! Who knew? (Not me;<) Since growing a bit older, I find I have several pockets of ignorance.

John Poole said...

Hey, Cassie.

I think we all do, and its just based on what holds our interests.

I tend to read almanacs quite a bit (which really amounts to just a lot of intellectual fidgeting), so I know when a lot of weird stuff like this happens.

On the other hand, I am often floored when I find myself ignorant of otherwise well-known things or events!

- John