Theos-Talk Archives (July 2005 Message tt00240)

Bart,
Ok, I may add to this as i look at the Google result, but here is one site 
with a short recitation on the Vulcan Observations:

<A HREF="http://www.nineplanets.org/hypo.html";>Hypothetical Planets</A>
http://www.nineplanets.org/hypo.html

>> The French mathematician <A HREF="http://www.nineplanets.org/help.html#leverrier";>Urbain Le Verrier</A>, co-predictor with <A HREF="http://www.nineplanets.org/help.html#adams";>J.C. Adams</A> 
of the position of <A HREF="http://www.nineplanets.org/neptune.html";>Neptune</A> before it was seen, in a lecture at 2 Jan 1860 
announced that the problem of observed deviations of the motion of <A HREF="http://www.nineplanets.org/mercury.html#orbit";>Mercury</A> could be 
solved by assuming an intra-Mercurial planet, or possibly a second <A HREF="http://www.nineplanets.org/asteroids.html";>asteroid 
belt</A> inside Mercury's orbit. The only possible way to observe this 
intra-Mercurial planet or asteroids was if/when they transited the Sun, or during total 
solar eclipses. Prof. Wolf at the Zurich sunspot data center, found a number of 
suspicious "dots" on the <A HREF="http://www.nineplanets.org/sol.html";>Sun</A>, and another astronomer found some more. A total 
of two dozen spots seemed to fit the pattern of two intra-Mercurial orbits, 
one with a period of 26 days and the other of 38 days. In 1859, Le Verrier 
received a letter from the amateur astronomer Lescarbault, who reported having seen 
a round black spot on the Sun on March 26 1859, looking like a planet 
transiting the Sun. He had seen the spot one hour and a quarter, when it moved a 
quarter of the solar diameter. Lescarbault estimated the orbital <A HREF="http://www.nineplanets.org/help.html#inclination";>inclination</A> to 
between 5.3 and 7.3 degrees, its longitude of node about 183 deg, its 
eccentricity "enormous", and its transit time across the solar disk 4 hours 30 minutes. 
Le Verrier investigated this observation, and computed an orbit from it: 
period 19 days 7 hours, mean distance from Sun 0.1427 a.u., inclination 12# 10', 
ascending node at 12# 59' The diameter was considerably smaller than Mercury's 
and its mass was estimated at 1/17 of Mercury's mass. This was too small to 
account for the deviations of Mercury's orbit, but perhaps this was the largest 
member of that intra-Mercurial asteroid belt? Le Verrier fell in love with the 
planet, and named it Vulcan. In 1860 there was a total eclipse of the Sun. Le 
Verrier mobilized all French and some other astronomers to find Vulcan - 
nobody did. Wolf's suspicious 'sunspots' now revived Le Verrier's interest, and 
just before Le Verrier's death in 1877 some more 'evidence' found its way into 
print. On April 4 1875, a German astronomer, H. Weber, saw a round spot on the 
Sun. Le Verrier's orbit indicated a possible transit at April 3 that year, and 
Wolf noticed that his 38-day orbit also could have performed a transit at 
about that time. That 'round dot' was also photographed at Greenwich and in 
Madrid. There was one more flurry after the total solar eclipse at July 29 1878, 
where two observers claimed to have seen in the vicinity of the Sun small 
illuminated disks which could only be small planets inside Mercury's orbit: J.C 
Watson (professor of astronomy at the Univ. of Michigan) believed he'd found TWO 
intra-Mercurial planets! Lewis Swift (co-discoverer of Comet Swift-Tuttle, which 
returned 1992), also saw a 'star' he believed to be Vulcan -- but at a 
different position than either of Watson's two 'intra-Mercurials'. In addition, 
neither Watson's nor Swift's Vulcans could be reconciled with Le Verrier's or 
Lescarbault's Vulcan. After this, nobody ever saw Vulcan again, in spite of 
several searches at different total solar eclipses. And in 1916, <A HREF="http://www.nineplanets.org/help.html#einstein";>Albert Einstein</A> 
published his General Theory of Relativity, which explained the deviations in the 
motions of Mercury without the need to invoke an unknown intra-Mercurial 
planet. In May 1929 Erwin Freundlich, Potsdam, photographed the total solar 
eclipse in Sumatra, and later carefully examined the plates which showed a profusion 
of star images. Comparison plates were taken six months later. No unknown 
object brighter than 9th magnitude was found near the Sun. But what did these 
people really see? Lescarbault had no reason to tell a fairy tale, and even Le 
Verrier believed him. It is possible that Lescarbault happened to see a small 
asteroid passing very close to the <A HREF="http://www.nineplanets.org/earth.html";>Earth</A>, just inside Earth's orbit. Such 
asteroids were unknown at that time, so Lescarbault's only idea was that he saw an 
intra-Mercurial planet. Swift and Watson could, during the hurry to obtain 
observations during totality, have misidentified some stars, believing they had 
seen Vulcan. "Vulcan" was briefly revived around 1970-1971, when a few 
researchers thought they had detected several faint objects close to the Sun during a 
total solar eclipse. These objects might have been faint <A HREF="http://www.nineplanets.org/comets.html";>comets</A>, and later 
comets have been observed that later did pass close enough to the Sun to collide 
with it. <<

This website seems to have a better chronology:

<A HREF="http://www.answers.com/topic/vulcan-planet";>Vulcan: Information From Answers.com</A>
http://www.answers.com/topic/vulcan-planet

John







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