C E R E S

Ceres lies within the main asteroid belt between the orbits of Mars and Jupiter, taking 4 years 7 months or 4.599 yr. to once orbit the Sun. Mean solar distance is 2.766 AU or roughly 410 million kilometres, but also varies throughout the orbit — aphelion to perihelion — by about 66 million kilometres or 0.44 A.U. It crosses on average about four different constellations each year, but does not necessarily remain aligned to the familiar twelve zodical constellations. Ceres’ orbit appears slightly elliptical at an eccentricity of 0.0792, whose ecliptical inclination is 10.59°. This allows the observable range of possible declinations to vary between +34.1° and −34.1°, placing this minor planet often within constellations well away from the zodiac. During 2006, for example, Ceres appeared in the southern constellations of Microscopium and Piscis Austrinus, while in 2007, it was found in Cetus for more than six months.

So far over sixty-four oppositions have been observed between 1830 and 2010, making the true orbit fairly well established. Over the decades, calculated ephemeris positions do suffer greatly from gravitational perturbations by nearby planetary bodies, which slowly change the astrometric positions. Such perturbations effects are mainly influenced by massive Jupiter, and to a much lesser extent, by both Mars and Pallas.

During certain oppositions, Ceres may brighten to about 6.8v magnitude, making it readily visible in binoculars as a bright star. When approaching its near yearly conjunctions with the Sun, brightness may fall around 9.5 magnitude.

In 2004, the Hubble Space Telesope discovered a very bright white surface spot, being likely occasioned by some past cometary collision. Its spectral signature and whitness appears to conclude that it composed of frozen water ice. (See Ceres Image.) This bright surface feature causes some small fluctuations in brightness, whose variability was first found by Johann Schröter in 1811. This has lead to the observed rotational period of 9 hours 04.5 minutes (0.3781 days) and the observed poles being tilted by 29.6° to us.

During mid-August 2006, a sub-committee of the International Astronomical Union (IAU) proposed Ceres be promoted to planet status, decided under new definitions for planets. I.e. Being massive enough to remain spherical. Ceres, in this case, is the only known gravitational body in the inner asteroid belt even close to being spherical. Had this been adopted for both Pluto’s moon Charon and Eris (UB 313 or aka Xena), Ceres would have been promoted to a fully-fledged planet, making twelve (12) planets in our Solar System. This idea, however, only lasted until 24th August 2006 when the vote was taken at the 26th IAU Conference in Prague, and the idea was rejected.

Instead an additional criteria for planet status was required. Presently, the IAU has classified Ceres as a dwarf planet — though there remains an uneasy disquiet among some IAU Commission delegates rergarding this change.

Ceres, in Roman mythology, is the daughter from the union of Saturn and Rhea, and is also wife and sister to Jupiter. Ceres’ mythological name is equivalent to Greek goddess Demeter, whose convoluted origin comes from the ancient celebrated Sicilian, and later Roman, goddess of harvest and grain. She was commonly ritual worshipped towards agriculture in increasing the genuine needs of a reliable food supply and for labourers in the fields careful tended to their crops. One of Ceres significant roles in Roman mythology was the important relationship of Ceres to her young daughter Perephata, later named, Proserpina, the Queen of the Underworld, whose equivalent story is aligned with the Greek goddess Persephone, the celebrated ancient goddess of Spring.

Conventional ancient stories about Ceres origins follows with Proserpina, who was an attractive and beautiful young woman greatly envied by Pluto, the Underworld god. She was once abducted and taken into Hades, where she was forcefully married to Pluto. Jupiter soon saw Ceres reaction of great despair and distress from loss of her daughter. However, his direct concerns were soon heightened when Ceres point-blank refused to come back to Olympus. She then began desperately searching the Earth for Proserpina. Soon Ceres started laying waste great areas of the Earth — now as deserts, and in spitefully retribution, even stopped the crops of fruits and grain growing wherever she walked. Jupiter soon found compromise with his brother, Pluto, by persuading him to release Proserpina for half of each each year. So when Proserpina now comes back to visit her mother, both goddessa generously disperse new seeds onto the ground, causing the plants to propagate with fruit. She joyously celebrates this event by decorating the Earth with colourful flowers. When six-months has elapsed, she then returns with the seasonal changes of autumn into Hades and her husband Pluto, where without her graces, all the plants slowly wither and lose their once vibrant colours — at least until she again triumphantly returns during the next seasonal spring.

This very popular story has real symbolic meaning regarding the growing of annual crops. This was something that was importantly increased during the large growing Roman city and regional population. In later times, the Romans became inordinately dependant on the need for foreign cereal and grain production, especially as most grain crops had first come from the island of Sicily. By the 2nd andd 1st Centuries B.C., this soon extended to grain importation from Spain or North Africa. Were it not for these distant regions, Rome could not have supported its large cosmopolitan population. At various times, grain was sometimes in short supply, causing distress

Ceres was honoured and worshipped by the plebeians, either once every four years, or then later annually. Here her many followers held secret rituals that occurred during the spring festival known as the Cerialia. Both Romans and Sicilians vigourously venerated her in the continuing hope of bountiful crops and avoidance of crop failures during times of severe drought or State budgetary hardships. Her worship was believed to have reached its pinnacle in c.496 BC.

Ceres, to some, is astronomically represented in the sky as the zodiacal constellation outline of Virgo, the virgin. Some have also attributed Virgo to the goddess Astraea now the 5th known minor planet, (Greek goddess Demeter.)

Ceres is mentioned in the famous Roman “The Satyricon” by Petronius Arbiter: Chapter 106;

“To Ceres, from her harvest,
the first fruits compelled to yield
And Bacchus with the fruitful vine to crown.”

Several 18th Century observers were first noted a relationship between the planets and the mean planetary distances, even before “Bode Law” was postulated. Even in 1596, Johannes Kepler (1571-1630) “Misterium Comographicum” had noted the inordinately large gap between Mars and Jupiter, but this was merely commented. One of the first was the Oxford Professor David Gregory (1659-1708) in his work “Astronomae elementa” (1702), followed by German popularist, Christian Freiherr von Wolff in 1741. This latter claim was examined by Johann Daniel Titus (1729-96), who was first to notice the planetary ‘gap’ missing in the orbital relationships. This was first published in “Comptemplation de la nature” in 1766. Here Titus modified Gregory’s relationship (now known as Bode’s Law) to produce the famous relationship;

d= [ 4 + 3 × ( 2n ) ] / 10

Where;
d = Distance in Astronomical Units and
n = Orbit Number Position of any Planet.

Here each more distant planet, has added the geometrically increasing numbers of 0, 3, 6, 12, 24, 48, 96, etc., to the value of 4, and always, only doubling the last numbers. From this sequence produces the known planetary distances all convert to astronomical units (A.U.) by dividing by ten. When appling this rule, the succession of geometric values follow Table 1.

Clearly Earth and all then five known planets do conveniently fit this rule. After William Herschel had discovered Uranus in 1781, these planetary position automatically fitted so-called Bode’s Law, then the only irresistible conclusion was that we could deduced that there was probably another planet plaaced between Mars and Jupiter.

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TABLE 1

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Planet     A.U.   Calculation
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Mercury    0.4    4+  0 =   4
Venus      0.7    4+  3 =   7
Earth      1.0    4+  6 =  10
Mars       1.5    4+ 12 =  16
??         ???    4+ 24 =  28
Jupiter    5.2    4+ 48 =  52
Saturn     9.5    4+ 96 = 100
Uranus    19.2    4+192 = 196
Neptune   29.9    4+384 = 388
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Towards this particular relationship, in 1772 the missing gap was again further extended by investigations made by Johann Elert Bode (1747-1826), who wanted to directly respond to Gregory’s “nonsense” proposal that the missing object might be just a moon of Mars. In 1776, Bode’s strong objection soon convinced him that another planet existed between the orbits of Mars and Jupiter. This also then drove him to further speculations into other possible more distant trans-Uranian planets. [By Neptune’s discovery in 1847, the sequence became questioned distances did not correspond to the law. Some interpreted this as being evidence of another planetary body beyond Neptune in the depths of the Solar System]. Soon this curious equation came very popular in both the astronomical community and general public, as it was believed to have some real cosmic significance.

These, and other speculations like Bode’s Law, lead to the eventual formation of the so-called ‘Celestial Police’ became the positive reinforcement for some serious search of these missing or new planetary bodies. von Zack immediately attempted to predicted various theoretical orbits in 1785, then beginning some rudimentary searches during 1787 — all without any success. By 1799, von Zack had requested the meeting of some of his prominent German colleagues that soon lead to the Celestial Police Society formation. At its very first formal meeting, this small observational group began organising its systematic search programme along the whole ecliptic and hoping to stumble upon this new undiscovered planet.

By September 1799, now only four months prior to Ceres’ discovery, there was another Society meeting at the observatory with the famed German visual observer, Johann Schröter’s. They had already realised that the search for these planets was mammoth undertaking, so they decided to employ more recruits to help with their observing tasks. One of these observers they desired was Piazzi Giuseppe, who was the head astronomer of the Sicilian Palermo Observatory. They directly considered his nomination as especially important because of the much better observing conditions in Sicily. Piazzi was also the natural choice for this project as he was doing regular observations in the production of his extensive new star catalogue. Within days a letter was dispatched to him.

It must have been bitterly disappointing to all of them that this introductory letter about their group had still been in transit to Piazzi at the time of the discovery. Although ‘losing their prize’ to someone ouside the group was upsetting, there was still much work to do. Although Ceres had been found on the 1st January 1801, it was soon became clear that it would soon be lost in the solar glare of the coming conjunction. At first, Piazzi thought the new celestial body was merely some comet, but on the next observing night the star had moved, but showed no indication of a tail. Timing of the discovery proved hard to ascertain its true motion, especially as the curved arc happened, on January 13, to coincide near the ending of the observed retrograde motion. Piazzi was to observe Ceres again on 11th January, but was unable to do further observations after this date because he become sick and was bedridden. His uncertainty soon continued to diminished as Ceres closed in the Sun — but he soon realised this new body’s movement against the background sky seemed far too slow for any comet. Yet without supporting observations, orbit computations were impossible, so Ceres just disappeared into solar conjuction without knowing where it would next appear in the morning sky.

Within three months, the new minor planet was again found by one of them. Its rediscovery was based only on the seemingly intuitive orbital calculations made by mathematician and astronomer, Karl Gauss (1777-1855). Gauss had amazingly and accurately predicted Ceres’ new position to the extent that it was within the general field of any medium-powered eyepiece. He was also first to calculated the orbit of Ceres, doing all the positional reductions himself. Now Ceres could always confidently be followed and recovered after its next and subsequent solar conjunctions.

Reality of their presumed single ‘missing planet’ was soon to posing too many unanswered questions — Ceres seemed much too faint and too small. Almost simultaneously, Sir William Herschel stated that Ceres diameter was merely “ …at under 100 miles.” (>161km), whose conclusion was based on the body always appearing star-like even using highest of magnifications. This small estimated size was soon confirmed using both orbital calculations and apparent magnitude. Ceres diameter was not really determined or approximated until the 20th Century. In 1994, ground radar determined this diameter as 930 km., which was only improved in 2004 by the Hubble Space Telescope (HST) as 975×905 km.

After about 1803 AD, this general view had been totally accepted by them, with Ceres was simply not big enough to be planet-sized. Herschel’s diameter was no better than a poor approximation, but amazingly, this diameter value was not really questioned nor change for many decades.

To solve this apparent dilemma of the missing planetary mass, Heinrich Wilhelm Matthäus Olbers began suggested that Ceres might be among several more of these small bodies. Soon these planetary observers were earnestly searching for more celestial bodies, soon resulting in the discovery of Juno and Vesta in 1804 and 1807, respectively.

Perhaps the biggest observational evidence for these bodies not being true planets was the discovered by Schröter. In his written letter to Heinrich Olbers, he clearly states that Ceres and Pallas visual magnitude observations seemed to show unusually variablity. Here Olbers correctly assumed that; “…these asteroids are irregular rather than round figures.” Since then, nearly all the other minor planets between Mars and Jupiter has confirm this statement was true. So far, Ceres seems to be the only one near to being actually spherical! As stated before in the introduction to this page, the variability, in this instance, is mostly caused by bright surface white spot on Ceres.

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 0h UT    R.A.   Decl.   Mag   Δ     r    El.  Con
 DATE        (J2000)      V   A.U.   A.U.  o       
***************************************************
 07 Jan  00 00.7 -09 51  9.1 3.101 2.921 070.4 Cet
 21 Jan  00 14.9 -07 33  9.2 3.271 2.914 060.4 Cet
 04 Feb  00 30.8 -05 10  9.2 3.425 2.905 050.9 Cet
 18 Feb  00 48.0 -02 45  9.2 3.558 2.897 041.8 Cet
 03 Mar  01 06.3 +00 19  9.2 3.669 2.888 033.0 Cet
 
 17 Mar  01 25.5 +02 04  9.1 3.754 2.879 024.5 Cet
 31 Mar  01 45.5 +04 25  9.0 3.813 2.869 016.5 Psc
 14 Apr  02 06.0 +06 40  8.9 3.845 2.860 009.2 Psc
 28 Apr  02 27.0 +08 49  8.8 3.850 2.850 005.5 Cet
 12 May  02 48.4 +10 48  8.9 3.828 2.840 010.1 Ari
 
 26 May  03 10.0 +12 39  9.0 3.780 2.829 017.3 Ari
 09 Jun  03 31.8 +14 18  9.1 3.707 2.818 024.8 Tau
 23 Jun  03 53.7 +15 45  9.1 3.610 2.808 032.6 Tau
 07 Jul  04 15.3 +17 01  9.1 3.491 2.797 040.5 Tau
 21 Jul  04 36.4 +18 04  9.1 3.351 2.786 048.6 Tau
 
 04 Aug  04 56.9 +18 56  9.0 3.193 2.775 057.0 Tau
 18 Aug  05 16.2 +19 37  9.0 3.019 2.763 065.8 Tau
 01 Sep  05 33.9 +20 11  8.9 2.833 2.752 075.1 Tau
 15 Sep  05 49.5 +20 38  8.7 2.638 2.741 085.0 Tau
 29 Sep  06 02.2 +21 03  8.5 2.441 2.730 095.7 Ori
 
 13 Oct  06 11.3 +21 31  8.3 2.248 2.719 107.4 Gem
 27 Oct  06 15.8 +22 05  8.1 2.067 2.708 120.3 Gem
 10 Nov  06 14.9 +22 47  7.8 1.908 2.697 134.6 Gem
 24 Nov  06 08.2 +23 39  7.4 1.784 2.687 150.2 Gem
 08 Dec  05 56.6 +24 36  7.1 1.707 2.676 167.0 Tau
 
 22 Dec  05 42.2 +25 29  6.8 1.685 2.666 175.0 Tau
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Opposition  Conjunction
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12 Aug 2006  22 Mar 2007
09 Nov 2007  28 Jun 2008
24 Feb 2009  31 Oct 2009
18 Jun 2010  30 Jan 2011
16 Sep 2011  26 Apr 2012
17 Dec 2012  17 Aug 2013

15 Apr 2014  10 Dec 2014
25 Jul 2015  03 Mar 2016
20 Oct 2016  05 Jun 2017
31 Jan 2018  07 Oct 2018
29 May 2019  14 Jan 2020

28 Aug 2020  07 Apr 2021
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