Halley's Comet Returned as Predicted - Dec. 25, 1758

The comet that Edmond Halley had calculated to return appeared as in the night sky as predicted on this day in 1758.

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Episode Transcript

Speaker 1 (00:01):
Welcome to This Day in History Class from how Stuff
Works dot Com and from the desk of Stuff You
Missed in History Class. It's the show where we explore
the past one day at a time with a quick
look at what happened today in history. Hello, I'm Holly Fry.
Welcome to the podcast. I am sitting in for Tracy V.
Wilson this week. It is December, so if you celebrate Christmas,

(00:26):
I hope you're having a merry Christmas. But on this
day in seventeen fifty eight, a very important thing happened.
Hallie's comment returned. That was important because it had been
predicted and it confirmed the work that Edmund Halley had
been doing. Edmund Halley, you will also sometimes hear it
pronounced Holly, sometimes Haley, but Haley is generally considered wrong,

(00:46):
and whether Hallie or Holly is correct is a matter
of some debate. I'm going with Hallie and Edmund Halley
first spotted the comment that would later be named for
him in two To be clear, this was not the
first time this comment had been spotted. It was just
the first time that Edmund Hallie saw it. Comments prior
to Hallie's work in astronomy were often associated with an

(01:08):
assortment of misconceptions. Historically, they had been thought to be
omens sent by deities, harbingers of some sort, or sometimes
just unpredictable and unexplained anomalies of the sky. In six four,
Hallie paid a visit to Isaac Newton to discuss issues
of celestial motion, and this meeting has become in and
of itself something of a famed moment in astronomy history,

(01:32):
a pivotal discussion that resulted in an expansion of human
knowledge regarding how the universe works. Newton, working on some
of the ideas that he and Halle had discussed and
sort of putting together some of the things that he
had already been working on, eventually published his work Mathematical
Principles of Natural Philosophy that's also known commonly as Prince Shipia,

(01:53):
which is an abbreviation of its original Latin title and
how he actually edited prince Shipia, and he paid for
his printing. He believed in it so much so he
became intimately acquainted with its contents, including Newton's calculations on
elliptical orbits. Edmund Halley began meticulously analyzing the orbits of
twenty four comet sightings that were on record. It was

(02:16):
using those calculations that Halley noticed that the orbits of
the comets that had been seen and reported in fifty
one and sixteen o seven appeared to be the same
one that he had seen in sixteen eighty two. With
additional examination of the data he had available, Edmund Halley
determined that the comment was on an orbit that took

(02:36):
about seventy six years to circle the Sun, with variables
such as planetary gravity shifting the time to be slightly
longer or shorter, and using that information, he then predicted
that the comet would once again fly by the Earth
in late seventeen fifty eight or early seventeen fifty nine.
When Halley initially made this prediction, he seemed pretty confident

(02:57):
about it, writing quote, I can undertake confidently to predict
the return of the comment in seventeen fifty eight, though
over the years his language and discussing this whole matter
became less assertive. He started saying things like I may
venture to foretell in a preface to discussing his prediction,
but throughout he was constantly refining his astronomical tables and

(03:20):
eventually he felt fairly certain once again of the time
frame that he had set for the comets predicted return.
And there were other astronomers working on this idea as well.
Alexis Claude Cliaut, for example, came to the conclusion that
the commet would return in seventeen fifty nine in the spring,
not seventeen fifty eight. Edmund Halley died in seventeen forty two,

(03:43):
so he did not live long enough to see if
his prediction was accurate, and he knew that would be
the case, and he famously wrote, quote, if it should
return according to our predictions, impartial posterity will not refuse
to acknowledge that this was first discovered by an Englishman,
and just as Edmund Halley had predicted, on Christmas seventeen

(04:03):
fifty eight, the commet was seen in the night sky,
and this was lauded as a massive validation for the
work of both Isaac Newton and Edmund Halley. Shortly after
the comets Christmas Day reappearance, French astronomer Nicola Luis de
la Chai, who also worked on calculating comet orbits, gave
the comet Hallie's name. Its official designation is actually one

(04:26):
P slash Halle. Since the eighteenth century, numerous sightings of
astronomical events have been determined to have been sightings of
Hallie's common The oldest documented sighting that is believed to
have possibly been Halley's comment happened in four sixty six
b C and was visible from ancient Greece. The next

(04:47):
time the comet is expected to pass by Earth is
the summer of one. I want to thank Eve's Jeff
Cote for her work on the research for this episode,
and Casey Pegram and Chandler Mays for they're always incredible
and professional audio work. If you would like to subscribe
to the podcast, you can do so. You can find
This Day in History on Apple Podcasts, on the I

(05:08):
Heart Radio app, and wherever else you get your podcasts.
Stick around tomorrow because we're going to talk a little
bit about a fairly new holiday tradition.