Ceres

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Ceres[1]

Symbol: A21_039.gif

Astronomy

  • Shape: Spheroid
Parameter Size
Semi-major axis 2.7675 AU (414,010,000 km)
Perihelion 2.5577 AU (382,620,000 km)
Aphelion 2.9773 AU (445,410,000 km)
Eccentricity 0.075823
Inclination 10.593° to ecliptic
Orbital period 4.60 yr (1,681.63 d)
Mean density 2.161 ± 0.009 g/ cm³
Dimensions 965 × 961 × 891 ± 2.0 km
Mean radius 473 km
Sidereal rotation period 0.378 d (9.074 h)
Albedo 0.09 ± 0.0033
Ceres (bottom left), the Moon and Earth.[2]

Ceres is now classified as a dwarf planet which orbits the Sun within the asteroid belt between Mars and Jupiter. It is known by astronomers as "1 Ceres" because it was the very first minor planet discovered on New Year's Eve 1801 by Giussepe Piazzi at the observatory in Palermo. It is the largest body in this belt. Composed of rock and ice, it is estimated to compose approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own gravity. Its average distance from the Sun is 414 million km. It needs 4.6 years to make one sidereal orbit. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest, it is too dim to be seen with the naked eye, except under extremely dark skies.

As big across as Texas, Ceres' nearly spherical body has a differentiated interior - meaning that, like Earth, it has denser material at the core and lighter minerals near the surface. Ceres appears to be differentiated into a rocky core and icy mantle, and may have a remnant internal ocean of liquid water under the layer of ice. Astronomers believe that water ice may be buried under its crust because its density is less than that of the Earth's crust, and because the dust-covered surface bears spectral evidence of water-bearing minerals. Ceres could even boast frost-covered polar caps. It is estimated that if Ceres were composed of 25 percent water, it may have more water than all the fresh water on Earth. Ceres' water, unlike Earth's, is expected to be in the form of water ice located in its mantle.[3]

Mythology

The asteroid was named after the Roman Goddess of fertility Ceres who was considered to be another personification of the Greek Goddess Demeter. Demeter was one of the six children resulting from the relationship between Rhea and Kronos (Latin for Saturn). Her brothers were Zeus (Jupiter), Poseidon (Neptune) and Hades (Pluto), her sisters Hestia (Vesta) and Hera (Juno). Although she belonged to the twelve great Olympian gods, she was rarely to be found in the kingdom of her powerful brother Zeus. She loved the Earth, particularly the fertile islands of the Mediterranean such as Sicily. There, her generosity allowed for lush vegetation and wellbeing. There was a shrine devoted to her in the Greek town of Eleusis.

Ceres with torch in search of Proserpina.[4]

There is a well-known Greek myth concerning her daughter Persephone. Zeus had promised her hand to Hades without consulting Demeter. In order to fulfil his promise, he lured Persephone to a forest clearing with beautiful Narcissi, the flowers of Hades. Demeter had always warned her daughter not to touch these flowers, but the young girl couldn't resist and picked a flower. When she did, the earth in front of her opened up and Hades appeared with his black steeds and carried her off into the Underworld.

When her daughter failed to appear, Demeter spent nine days searching for her. Hecate then told her what had happened. Full of grief at losing her daughter, she withered all forms of life on Earth. People and animals were threatened with extinction and Zeus was afraid that he would receive no more sacrifices. So he sent various messengers to his sister but she was so full of grief that no one could appease her. In order to prevent all life from being destroyed, Zeus negotiated with Hades who released Persephone. However, Hades gave Persephone a pomegranate - the symbol of marriage – and when she ate from it she was tied to him forever. In the end, the gods agreed that Persephone should spend two thirds of the year with her mother Demeter above ground, and the other third – after the harvest – with her spouse. Demeter also agreed to this and gave life back to Earth.

Interpretation

In astrology, Ceres is concerned with fertility, motherhood, sustenance and ecology, but also with growing up and the process of letting go. Ceres is the challenge to strike the right balance between protecting and letting go, between nurturing and neglecting. Ceres cautions us not to be too possessive of children and other loved-ones, but to allow them to go their own way when the time has come. Themes such as abuse and eating disorders are also associated with Ceres.

Ceres appears to be related to the signs of Cancer and Virgo and may have its domicile there or be exalted. It also appears to be related to the Taurus/Scorpio axis.

Weblinks

Medieval Ceres.[5]

Notes and References

  1. Viewed from the Dawn spacecraft 4 May 2015 at a distance of 13,600 km (8,400 mi).
  2. Shown to scale.
  3. nasa.gov/mission_pages/dawn
  4. Medaillon by Martial Reymond, early 17th century.
  5. Above the island of Sicily.