Editing Vulcan (hypothetical planet) (section)

== Hypotheses and observations ==

Celestial bodies interior to the orbit of Mercury had been hypothesized, searched for, and were even claimed to have been observed, for centuries.{{citation needed|date=January 2023}}

Claims of seeing objects passing in front of the Sun included those made by the German astronomer [[Christoph Scheiner]] in 1611 (which turned out to be the discovery of [[sunspot]]s),<ref>{{cite journal | last = Drobyshevskii | first = E. M. | title = Impact Avalanche Ejection of Silicates from Mercury and the Evolution of the Mercury / Venus System | journal = Soviet Astr | volume = 36 | issue = 4 | pages = 436–443 | date=1992| bibcode = 1992SvA....36..436D}}</ref> British lawyer, writer and amateur astronomer [[Capel Lofft]]'s observations of 'an opaque body traversing the sun's disc' on 6 January 1818,<ref>{{Cite journal|url=https://babel.hathitrust.org/cgi/pt?id=njp.32101064253428;view=2up;seq=112;skin=mobile|title=The Monthly magazine. v.45 (1818). - Full View {{!}} HathiTrust Digital Library {{!}} HathiTrust Digital Library|journal=Monthly Magazine and Critical Register of Books|year=1796|language=en|access-date=2017-07-04|last1=Blake|first1=William}}</ref> and Bavarian physician and astronomer [[Franz von Paula Gruithuisen]]'s 26 June 1819 report of seeing "two small spots...on the Sun, round, black and unequal in size".<ref name="articles.adsabs.harvard.edu">{{Cite journal |title=The Supposed New Planet Vulcan|journal=Astronomical Register|volume = 7|page=164|last=Elger|first=T.G.E.|date=May 4, 1869|bibcode=1869AReg....7..164E}}</ref> German astronomer {{ill|Johann Wilhelm Pastorff|lt=J. W. Pastorff|de}} reported many observations also claiming to have seen two spots, with the first observation on 23 October 1822 and subsequent observations in 1823, 1834, 1836, and 1837; in 1834 the larger spot was recorded as 3 [[Minute and second of arc|arcseconds]] across, and the smaller 1.25 arcseconds.<ref name="articles.adsabs.harvard.edu"/>

Proposals that there could be planets orbiting inside Mercury's orbit were put forward by British scientist [[Thomas Dick (scientist)|Thomas Dick]] in 1838<ref name=Baum>{{cite book
| last1=Baum
| first1=Richard P.
| last2=Sheehan
| first2=William
| title=In Search of Planet Vulcan: The Ghost in Newton's Clockwork
| date=August 2003
| publisher=[[Basic Books]]
| location=New York
| isbn=0738208892}}</ref>{{rp|page=264}} and by French physicist, mathematician, and astronomer [[Jacques Babinet]] in 1846 who suggested there may be "incandescent clouds of a planetary kind, circling the Sun" and proposed the name "Vulcan" (after the god [[Vulcan (mythology)|Vulcan]] from [[Roman mythology]]) for a planet close to the Sun.<ref name=Baum/>{{rp|page=156}}

As a planet near the Sun would be lost in its glare, several observers mounted systematic searches to try to catch it during "[[astronomical transit|transit]]", i.e. when it passes in front of the Sun's disc. German amateur astronomer [[Heinrich Schwabe]] searched unsuccessfully on every clear day from 1826 to 1843 and [[Yale]] scientist [[Edward Claudius Herrick]] conducted observations twice daily starting in 1847, hoping to catch a planet in transit.<ref name=Baum/>{{rp|page=264}} French physician and amateur astronomer [[Edmond Modeste Lescarbault]] began searching the Sun's disk in 1853, and more systematically after 1858, with a 3.75 inch (95&nbsp;mm) [[refractor]] in an observatory he set up outside his surgery.<ref name=Baum/>{{rp|page=146}}