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Speaker 1: This Day in History Class is a production of iHeartRadio,

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Speaker 1: Hello and Welcome to This Day in History Class, a

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Speaker 1: show that uncovers a little bit more about history every day.

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Speaker 1: I'm Gabe Lucier, and in this episode, we're talking about

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Speaker 1: one of the most widely observed comets in history and

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Speaker 1: the two armchair astronomers who spotted it first. The day

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Speaker 1: was July twenty third, nineteen ninety five. Amateur astronomers Alan

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Speaker 1: Hale and Thomas Bop independently and simultaneously discovered a comet

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Speaker 1: officially designated Comet c SLASH nineteen ninety five oh one,

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Speaker 1: it was more commonly known as Comet hail Bop in

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Speaker 1: honor of its two discoverers. Hail Bop first became visible

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Speaker 1: without a telescope in May of nineteen ninety six, and

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Speaker 1: it didn't fade from view until December of the following year.

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Speaker 1: That eighteen month long appearance was double the nine month

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Speaker 1: record previously set in eighteen eleven, and at the time

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Speaker 1: of recording, it's still the longest period of time that

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Speaker 1: a comet has ever remained visible to the naked eye.

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Speaker 1: The reason for that high visibility is that Comet hail

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Speaker 1: Bop was an unusually bright comet. In fact, it appeared

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Speaker 1: one thousand times brighter than the famous Haley's Comet had

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Speaker 1: when it streaked by at roughly the same distance in

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Speaker 1: nineteen eighty six. As for why it was so bright,

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Speaker 1: that's because of the comet's abnormally large size. The nucleus

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Speaker 1: of a comet, that is, the solid core, is typically

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Speaker 1: about one to two miles across. The nucleus of Haley's

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Speaker 1: comet was an outlier at approximately ten miles across, But

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Speaker 1: hail Bop was on a whole other level. According to NASA,

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Speaker 1: its nucleus measured about thirty seven miles in diameter. Because

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Speaker 1: of that massive surface area and the huge amount of

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Speaker 1: light it reflected, hail Bop was highly visible in our

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Speaker 1: night skies, even though it was farther from the Earth

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Speaker 1: than the Earth is from the Sun. All the comets

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Speaker 1: in our Solar System, no matter how bright they are,

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Speaker 1: come from two specific regions in space, the Kuiper Belt

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Speaker 1: and the Ort Cloud. Both are debris fields made up

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Speaker 1: of small icy bodies on the edge of our Solar System,

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Speaker 1: and on occasion, one of those icy bodies will become

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Speaker 1: dislodged and be sent hurtling on an elliptical orbit around

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Speaker 1: the Sun. These are what we call comets, large dirty

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Speaker 1: snowballs composed of densely packed ice and dust. They become

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Speaker 1: visible as they approach the Sun and begin to warm up.

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Speaker 1: The nucleus starts to evaporate, creating a hazy cloud around it,

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Speaker 1: as well as tales of gases and dusts that streak

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Speaker 1: out behind. Of the two comet producing regions, the Kuiper

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Speaker 1: Belt is significantly closer to Earth and is located between

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Speaker 1: Neptune and Pluto, so still pretty far away. The comets

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Speaker 1: that hail from here are known as short period comets,

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Speaker 1: as it takes them less than two hundred years to

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Speaker 1: make one orbit around the Sun. Haley's Comet is perhaps

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Speaker 1: the most well known in this class. It was last

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Speaker 1: seen from Earth in nineteen eighty six and is expected

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Speaker 1: to return to our view in twenty sixty one. As

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Speaker 1: you've probably worked out by now, comets that originate in

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Speaker 1: the Ort Cloud begin their journey from beyond Neptune and

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Speaker 1: are known as long period comets. Their orbits take anywhere

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Speaker 1: from several hundred to several thousand years to complete, making

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Speaker 1: their sightings a true once in a lifetime experience for humans.

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Speaker 1: Comet hail Ba is a long period comet that's believed

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Speaker 1: to have formed some four billion years ago. It's made

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Speaker 1: the trip around the Sun numerous times since then, but

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Speaker 1: it won't be seen this way again for at least

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Speaker 1: another twenty five hundred years. It's rare for a comet

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Speaker 1: to be large, close and bright enough to be seen

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Speaker 1: with the naked eye, but dimmer comets are fairly common,

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Speaker 1: and at least a few of them are discovered each year,

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Speaker 1: some by human observers, but most by automated spacecraft. Comet

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Speaker 1: hail Bop was an exception in this regard as well.

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Speaker 1: It was discovered not just by an amateur astronomer, but

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Speaker 1: by two of them. It was on a clear night

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Speaker 1: in late July of nineteen ninety five that Alan Hale

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Speaker 1: set up his personal telescope in the driveway of his

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Speaker 1: new Mexico home. He worked professionally in space research, but

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Speaker 1: comet spotting was just his late night hobby. That night,

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Speaker 1: he was planning to observe known comic that were expected

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Speaker 1: to come into view, but as he waited for them

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Speaker 1: to appear, he pointed his telescope at a globular cluster

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Speaker 1: in the Sagittarius system just to see what he could see.

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Speaker 1: To Hale's surprise, there was a fuzzy object in the

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Speaker 1: field that hadn't been there when he checked the same

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Speaker 1: location two weeks earlier. He consulted his deep sky catalogs

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Speaker 1: and star charts to make sure he wasn't mistaken, and

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Speaker 1: after confirming that he had indeed found something new, he

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Speaker 1: shot off an email to the International Astronomical Union informing

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Speaker 1: them of his discovery. Meanwhile, one stayed away in Arizona,

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Speaker 1: a factory manager named Thomas Bob had cited the comet

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Speaker 1: as well. He had spent decades observing deep sky objects

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Speaker 1: in his spare time, and on that fateful night, he

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Speaker 1: had gone out comet hunting with a group of friends.

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Speaker 1: Bob didn't actually own a telescope of his own at

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Speaker 1: the time, but as he peered into a friend's telescope,

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Speaker 1: he saw a strange, fuzzy object past into his field

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Speaker 1: of view. After having his friends verify what he had seen,

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Speaker 1: Bop also fired off a message to the IAU sharing

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Speaker 1: his observations. In the early morning of July twenty third,

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Speaker 1: the Central Bureau verified both men's finding shortly after, and

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Speaker 1: when comparing the times of the discovery, they were shocked

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Speaker 1: to find that Hale and Bop had cited the comet

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Speaker 1: at the same time. The news of the comet was

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Speaker 1: officially announced about twelve hours after its initial discovery, with

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Speaker 1: Hale and Bop sharing the credit by sheer coincidence. According

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Speaker 1: to NASA, at a distance of about six hundred and

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Speaker 1: sixty five million miles from our Sun, it was the

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Speaker 1: farthest comet ever to be discovered by amateur astronomers for

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Speaker 1: at least so far. I'm Gay, Bluesyay, and hopefully you

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Speaker 1: now know a little more about history today than you

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Speaker 1: did yesterday. If you'd like to keep up with the show,

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Speaker 1: you can follow us on Twitter, Facebook, and Instagram at

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Speaker 1: TDI HC Show, and if you have any comments or suggestions,

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Speaker 1: feel free to send them my way by writing to

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Speaker 1: this Day at iHeartMedia dot com. Thanks to Casby Bias

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Speaker 1: for producing the show, and thanks to you for listening.

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Speaker 1: I'll see you back here again tomorrow for another day

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Speaker 1: in History Class