<p>It's surprisingly hard to research this, partly because the name &quot;H-alpha&quot; only became common towards the end of the 19th Century, and partly because (I get the impression) a lot of mid- and late-19th Century spectroscopy ignored the red end of the spectrum, perhaps because the equipment was less sensitive there. Thus, you can find a fair amount of discussion from the late 19th Century about emission lines from nebulae which are focused on the blue region of the spectrum, with a mysterious line near 5005 or 5006 Angstrom (what we now know is [O III] 5007) referred to as the &quot;principal line&quot;, and no mention of H-alpha at all.</p>
<p>Nevertheless, it seems pretty clear that <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1866.0036" rel="noreferrer">Huggins &amp; Miller observed H-alpha in emission from the 1866 outburst</a> of the recurrent nova <a href="https://en.wikipedia.org/wiki/T_Coronae_Borealis" rel="noreferrer">T Corona Borealis</a> -- they noted the appearance of a bright line near or at &quot;Fraunhofer's C&quot; line (the old name for H-alpha), and referred to its association with hydrogen as &quot;extremely probable&quot;. (Even clearer is an emission line at the location of &quot;Fraunhofer's F&quot; line, which is H-beta.) I think this might qualify as the first real astronomical observation of H-alpha in emission.</p>
<p>The earliest observation of H-alpha in emission from the Sun was by the French scientist <a href="https://en.wikipedia.org/wiki/Pierre_Janssen" rel="noreferrer">Pierre Janssen</a> in 1868, during an eclipse of the Sun, when he passed the light from the solar corona through a spectrograph and recorded the spectrum on a photographic plate. (He also observed a mystery emission line that turned out to be the first evidence for helium.)</p>

CC BY-SA 4.0
2021-06-08T20:34:05.570Z
2021-06-08T20:34:05.570Z
Peter Erwin
<p>Seemingly easy question, but actually not trivial to answer.</p>
<p><a href="https://en.wikipedia.org/wiki/H-alpha" rel="nofollow noreferrer">Wikipedia on H-alpha</a> as well as other entries in other encyclopedias obviously mention the <a href="https://en.wikipedia.org/wiki/Balmer_series" rel="nofollow noreferrer">Balmer series</a> and that the spectral line was discovered by <a href="https://en.wikipedia.org/wiki/Johann_Jakob_Balmer" rel="nofollow noreferrer">Johann Balmer</a> in 1885, but that does not answer your question about the first astronomical observation. The <a href="https://en.wikipedia.org/wiki/Balmer_jump" rel="nofollow noreferrer">article on the Balmer jump</a> cites a <a href="https://en.wikipedia.org/wiki/Balmer_jump" rel="nofollow noreferrer">publication as early as 1957</a>, but I am doubtful whether that is really the first publication on the topic.</p>
<p>Using <a href="https://books.google.com/ngrams/graph?content=H+alpha%2CH%CE%B1%2Cbalmer%2Clyman&amp;year_start=1880&amp;year_end=2000&amp;corpus=26&amp;smoothing=3" rel="nofollow noreferrer">google ngrams</a> on a book-standard <a href="https://en.wikipedia.org/wiki/Text_corpus" rel="nofollow noreferrer">corpus</a> as oracle, you could obtain pictures as the following:
<a href="https://i.sstatic.net/WRk0K.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/WRk0K.png" alt="ngram graph" /></a></p>
<p>There is no prominent peak for any of the keywords <code>lyman</code>, <code>H alpha</code>, or <code>balmer</code>  which might support my hypothesis, that the first (astronomical) use of Balmer's discovery before mid 1950. However, I cannot explain the two maxima of the (blue) <code>H alpha</code> line (pun intended) in the ngram time series.</p>

CC BY-SA 4.0
2021-06-07T19:41:37.030Z
2021-06-09T10:05:51.413Z
2021-06-09T10:05:51.413Z
B--rian
<p>The H-alpha line is used by astronomers to trace the presence of hydrogen in galaxies or to view protuberances on the Sun. When was the H-alpha emission of astronomical objects such as galaxies first observed ?</p>

<observational-astronomy><history><h-alpha>
When was H-alpha first used to observe the universe?
usernumber
# When was H-alpha first used to observe the universe?

(Asked by: username_0 on 2021-06-05)

The H-alpha line is used by astronomers to trace the presence of hydrogen in galaxies or to view protuberances on the Sun. When was the H-alpha emission of astronomical objects such as galaxies first observed ?

**Tags:** observational-astronomy, history, h-alpha

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## 2 answers

### Answer by username_1 on 2021-06-08. Score: 6 | Accepted answer

It's surprisingly hard to research this, partly because the name "H-alpha" only became common towards the end of the 19th Century, and partly because (I get the impression) a lot of mid- and late-19th Century spectroscopy ignored the red end of the spectrum, perhaps because the equipment was less sensitive there. Thus, you can find a fair amount of discussion from the late 19th Century about emission lines from nebulae which are focused on the blue region of the spectrum, with a mysterious line near 5005 or 5006 Angstrom (what we now know is [O III] 5007) referred to as the "principal line", and no mention of H-alpha at all.

Nevertheless, it seems pretty clear that [Huggins & Miller observed H-alpha in emission from the 1866 outburst](https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1866.0036) of the recurrent nova [T Corona Borealis](https://en.wikipedia.org/wiki/T_Coronae_Borealis) -- they noted the appearance of a bright line near or at "Fraunhofer's C" line (the old name for H-alpha), and referred to its association with hydrogen as "extremely probable". (Even clearer is an emission line at the location of "Fraunhofer's F" line, which is H-beta.) I think this might qualify as the first real astronomical observation of H-alpha in emission.

The earliest observation of H-alpha in emission from the Sun was by the French scientist [Pierre Janssen](https://en.wikipedia.org/wiki/Pierre_Janssen) in 1868, during an eclipse of the Sun, when he passed the light from the solar corona through a spectrograph and recorded the spectrum on a photographic plate. (He also observed a mystery emission line that turned out to be the first evidence for helium.)


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### Answer by username_2 on 2021-06-07. Score: 4

Seemingly easy question, but actually not trivial to answer.

[Wikipedia on H-alpha](https://en.wikipedia.org/wiki/H-alpha) as well as other entries in other encyclopedias obviously mention the [Balmer series](https://en.wikipedia.org/wiki/Balmer_series) and that the spectral line was discovered by [Johann Balmer](https://en.wikipedia.org/wiki/Johann_Jakob_Balmer) in 1885, but that does not answer your question about the first astronomical observation. The [article on the Balmer jump](https://en.wikipedia.org/wiki/Balmer_jump) cites a [publication as early as 1957](https://en.wikipedia.org/wiki/Balmer_jump), but I am doubtful whether that is really the first publication on the topic.

Using [google ngrams](https://books.google.com/ngrams/graph?content=H+alpha%2CH%CE%B1%2Cbalmer%2Clyman&year_start=1880&year_end=2000&corpus=26&smoothing=3) on a book-standard [corpus](https://en.wikipedia.org/wiki/Text_corpus) as oracle, you could obtain pictures as the following:
[![ngram graph](https://i.sstatic.net/WRk0K.png)](https://i.sstatic.net/WRk0K.png)

There is no prominent peak for any of the keywords `lyman`, `H alpha`, or `balmer` which might support my hypothesis, that the first (astronomical) use of Balmer's discovery before mid 1950. However, I cannot explain the two maxima of the (blue) `H alpha` line (pun intended) in the ngram time series.


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