Editing History of astronomy (section)

===19th century===
[[Image:Karte Mars Schiaparelli MKL1888.png|thumb|[[Mars]] surface map of [[Giovanni Schiaparelli]]]]

Pre-photography, data recording of astronomical data was limited by the human eye. In 1840, [[John W. Draper]], a chemist, created the earliest known astronomical photograph of the Moon. And by the late 19th century thousands of photographic plates of images of planets, stars, and galaxies were created. Most photography had lower quantum efficiency (i.e. captured less of the incident photons) than human eyes but had the advantage of long integration times (100 ms for the human eye compared to hours for photos). This vastly increased the data available to astronomers, which led to the rise of [[human computers]], famously the [[Harvard Computers]], to track and analyze the data.

Scientists began discovering forms of light which were invisible to the naked eye: [[X-ray]]s, [[gamma ray]]s, [[radio wave]]s, [[microwave]]s, [[ultraviolet radiation]], and [[infrared radiation]]. This had a major impact on astronomy, spawning the fields of [[infrared astronomy]], [[radio astronomy]], [[x-ray astronomy]] and finally [[gamma-ray astronomy]]. With the advent of [[spectroscopy]] it was proven that other stars were similar to the Sun, but with a range of [[temperature]]s, [[mass]]es and sizes.

The science of [[astronomical spectroscopy|stellar spectroscopy]] was pioneered by [[Joseph von Fraunhofer]] and [[Angelo Secchi]]. By comparing the spectra of stars such as [[Sirius]] to the Sun, they found differences in the strength and number of their [[spectral line|absorption lines]]—the dark lines in stellar spectra caused by the atmosphere's absorption of specific frequencies. In 1865, Secchi began classifying stars into [[stellar classification|spectral types]].<ref>{{cite web
 | last=MacDonnell | first=Joseph
 | url=http://www.faculty.fairfield.edu/jmac/sj/scientists/secchi.htm
 | archive-url=https://web.archive.org/web/20110721210124/http://www.faculty.fairfield.edu/jmac/sj/scientists/secchi.htm
 | archive-date=2011-07-21
 | title=Angelo Secchi, S.J. (1818–1878) the Father of Astrophysics
 | publisher=[[Fairfield University]]
 | access-date=2006-10-02}}</ref> The first evidence of helium was observed on August 18, 1868, as a bright yellow spectral line with a wavelength of 587.49 nanometers in the spectrum of the chromosphere of the Sun. The line was detected by French astronomer Jules Janssen during a total solar eclipse in Guntur, India.

The first direct measurement of the distance to a star ([[61 Cygni]] at 11.4 [[light-years]]) was made in 1838 by [[Friedrich Bessel]] using the [[parallax]] technique. Parallax measurements demonstrated the vast separation of the stars in the heavens.{{Citation needed|date=October 2021}} Observation of double stars gained increasing importance during the 19th century. In 1834, Friedrich Bessel observed changes in the proper motion of the star Sirius and inferred a hidden companion. [[Edward Charles Pickering|Edward Pickering]] discovered the first [[spectroscopic binary]] in 1899 when he observed the periodic splitting of the spectral lines of the star [[Mizar (star)|Mizar]] in a 104-day period. Detailed observations of many binary star systems were collected by astronomers such as [[Friedrich Georg Wilhelm von Struve]] and [[Sherburne Wesley Burnham|S. W. Burnham]], allowing the masses of stars to be determined from the computation of [[orbital elements]]. The first solution to the problem of deriving an orbit of binary stars from telescope observations was made by Felix Savary in 1827.<ref>{{cite book
 | first=Robert G. | last=Aitken | title=The Binary Stars | page=66
 | publisher=Dover Publications Inc. | location=New York
 | date=1964 | isbn=978-0-486-61102-0}}</ref>
In 1847, [[Maria Mitchell]] discovered a comet using a telescope.