nPostednon August 18, 2014
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Frenchnastronomer Pierre Janssen traveled all the way to Guntur, India, tonwatch a solar eclipse on this date in 1868. Of course, Janssen didn’tnjust watch the eclipse—he studied it—and he discovered somenimportant things about the Sun.
Frenchnastronomer Pierre Janssen traveled all the way to Guntur, India, tonwatch a solar eclipse on this date in 1868. Of course, Janssen didn’tnjust watch the eclipse—he studied it—and he discovered somenimportant things about the Sun.n
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nIt’snwonderful that we CAN discover things about an object 93 millionnmiles away!
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nWhatndid Janssen discover? He observed bright lines in the spectrum of thenouter atmosphere of the Sun – a layer called the chromosphere –nthat showed that it is gaseous. n
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Onenof the lines was a very bright yellow line that was, it turned out, an indication of an element that had never been discovered.
Onenof the lines was a very bright yellow line that was, it turned out, an indication of an element that had never been discovered. n
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nThe bright yellow line was helium – you know, the super-lightweight gas that we oftennuse to fill balloons and blimps, so that they will float in the air.
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nJanssennnoted that the chromospheric lines were so bright, they could benobserved even without an eclipse. This paved the way for studyingnsolar prominences without having to wait for—and travel to—a rarentotal solar eclipse. n
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Janssenneven went on to demonstrate the ability to observe spectral linesnwithout an eclipse. n
Janssenneven went on to demonstrate the ability to observe spectral linesnwithout an eclipse. nn
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nBynthe way, Janssen’s discovery of helium was made again just a fewnmonths later—separately, independently—by the English astronomernJoseph Norman Lockyer.
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nBecause Lockyer went further, testing with anchemist to see exactly what element made the line, Lockyer was thenone who got to name the new element, and today he shares credit fornhelium’s discovery with Janssen. n
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nChecknout this spectacular example of a solar prominence! And here and here are more average solarnprominences. (Note that each prominence dwarfs the Earth in size, as shown in this scale drawing, left.)
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nAlsonon this date:
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Cupcake Day
Cupcake Day
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nSerendipity Day
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nSerendipity Day
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nBadnPoetry Day
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Anniversarynof the start of the Wilkes Expedition
Anniversarynof the start of the Wilkes Expeditionn
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nAnniversarynof the first child of English parents to be born in the Americas
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nDisappearancenDay
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nPlannahead:
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nChecknout my Pinterest boards for:
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nAugustn holidays
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nAugustn birthdays
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nHistoricaln anniversaries in August
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nAndnhere are my Pinterest boards for:
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nSeptembern holidays
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nSeptembern birthdays
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nHistoricaln anniversaries in September
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