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Speaker 1: This Day in History Class. It's a production of I

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Speaker 1: Heart Radio. Hey y'all, I'm Eves and welcome to this

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Speaker 1: Day in History class, where we uncover a new layer

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Speaker 1: of history every day. Today is January nine. The day

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Speaker 1: was January nine. Radio astronomers Alexander Volsten and Dale Frail

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Speaker 1: announced the discovery of two planets orbiting the pulsar p

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Speaker 1: s R B twelve fifty seven plus twelve. It was

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Speaker 1: the first confirmed discovery of exo planets. Exo Planets are

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Speaker 1: planets beyond our Solar System. People have thought that there

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Speaker 1: were planets around other stars for centuries, but the scientists

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Speaker 1: did not have the tools to detect them, and there

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Speaker 1: was no way to know what extra Solar system looked

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Speaker 1: like and whether there was life there. Astronomers in the

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Speaker 1: nineteenth century claimed that they've seen exo planets, but their

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Speaker 1: observations were discredited. The first evidence of a possible exo

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Speaker 1: planet orbiting a white dwarf named van man in two

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Speaker 1: was recorded in nineteen seventeen, and in nineteen eight scientists

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Speaker 1: first proposed the existence of the exo planet Gamma c

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Speaker 1: f I A B, but it was not confirmed to

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Speaker 1: be an orbit around the star Gamma c f I

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Speaker 1: A until two thousand and two. Using the ad CBO

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Speaker 1: Observatory in Puerto Rico, astronomers Vulsion and Frail searched for

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Speaker 1: new pollstars. In February of nineteen ninety, Vulsion discovered a

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Speaker 1: pulsar in the constellation Virgo that spun on this axis

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Speaker 1: one hundred and sixty one times per second for a

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Speaker 1: rotation period of six point twenty two milliseconds. The polsar

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Speaker 1: was called p s R twelve fifty seven plus twelve

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Speaker 1: when ps R standing for pulsating source of radio and

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Speaker 1: the following numbers representing the pulsars right ascension and degrees

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Speaker 1: of declination. Modern conventions prefix older pulsar names with the

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Speaker 1: letter B, since before pulsars were given names according to

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Speaker 1: their positions in the B nineteen fifty coordinate system. Now

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Speaker 1: they're given names based on their position in the J

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Speaker 1: two thousand coordinate system. But the pulsar had a regularities

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Speaker 1: in its pulsation period, Vulsion and Frail discovered that there

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Speaker 1: were at least two planets orbiting PSR B twelve fifty

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Speaker 1: seven plus twelve. The XCEL planets were named ps R

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Speaker 1: twelve fifty seven plus twelve C and ps R twelve

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Speaker 1: fifty seven plus twelve D or Poltergeist and Fobitour, respectively.

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Speaker 1: Both are around four times as massive as Earth. One

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Speaker 1: has an orbital period of sixty six point five days

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Speaker 1: and the other point two days. Because the exo planets

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Speaker 1: are constantly hit with radiation from the pulsar they're orbiting,

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Speaker 1: they are rocky and cannot support organic life. On January nine,

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Speaker 1: Frill and Vulsion published a paper in the journal Nature

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Speaker 1: announcing their discovery of the two exo planets. Two years later,

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Speaker 1: Vulsion and his colleague Mac Konaki discovered a third planet

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Speaker 1: in the system. It is less massive than Earth and

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Speaker 1: has an orbital period of twenty five point three days.

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Speaker 1: The planets likely formed from matter ejected into space during

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Speaker 1: the supernova explosion that created the pulsar. In Michelle Mayor

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Speaker 1: and Didya k Low discovered the first known exo planet

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Speaker 1: orbiting a star similar to the Sun. Since thousands of

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Speaker 1: exo planets have been discovered, most of them confirmed by

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Speaker 1: NASA's Kepler Space telescope using the transit method. The transit

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Speaker 1: method did texts exo planets by measuring the dimming of

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Speaker 1: a star as an orbiting body passes between it and Earth.

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Speaker 1: If the demming happens at regular intervals and last a

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Speaker 1: set amount of time, then it's likely that a planet

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Speaker 1: is orbiting the star. The intensity of the dimming helps

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Speaker 1: scientists determine the size ratio between the star and the

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Speaker 1: planet Excel Planets have also been discovered using other indirect methods,

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Speaker 1: like the radial velocity method. I'm Eves Jeff Coo and

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

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Speaker 1: you did yesterday. I want to impress your Internet crush,

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Speaker 1: show them your history smarts by sharing something you learned

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Speaker 1: on the show. Don't forget to tag us at t

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Speaker 1: d I h C podcast. Our email address is this

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Speaker 1: day at I heart media dot com. Thanks for listening,

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Speaker 1: Mary History to all, and to all a good night. Yeah.

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