Ceres

Ceres is a dwarf planet and the largest astronomical object in the asteroid belt, a region of the solar system that lies between the orbits of Mars and Jupiter.

In the cover image, two bright spots are seen in the Oxo (center) and Haulani (right) craters.

The substance that these stains mainly contain is sodium carbonate. Also visible is Ahura Mons, an isolated hill, in the lower right.

At the beginning of the 21st century, after the new definition of “planet“, Ceres was inscribed in the category of “dwarf planet“.

When was Ceres discovered?

In 1766, a German scientist named Johann Titius conjectured that the distance of the planets from the Sun followed a certain mathematical relationship.

It must be borne in mind that in those years Uranus, Neptune and Pluto had not yet been discovered.

Six years later, another German, Johann Bode refined this hypothesis, and spread it within the scientific community.

Titius Law
Titius-Bode law. Credit: Wikipedia.

Since then, the theory of Titius and Bode was gaining prestige and the idea that there must be a planet located between Mars and Jupiter became general.

Titius-Bode’s mathematical hypothesis is very ingenious:

  • 1st, we must add 4 to each number in the series: 0 – 3 – 6 – 12 – 24 – 48 – 96 -192 – 384.
  • 2nd, then dividing each result by 10, the distances of the planets to the Sun are obtained ”.

Titius-Bode assigned the value of 1 to Earth, whose distance from the Sun is 150 million km. This last figure is called the Astronomical Unit.

Whereby,

  • (0 + 4): 10 = 0.4 would be the distance to the Sun from the planet Mercury (60 million km). Real data: Mercury is located an average of 57,910,000 km away from the Sun.
  • (3 + 4): 10 = 0.7 would be the distance to the Sun from the planet Venus (70 million km). Real data: Venus is located an average of 57,910,000 km away from the Sun.
  • (6 + 4): 10 = 1.0 would be the distance to the Sun from planet Earth (150 million km). Real data: the Earth is located an average of 146,600,000 km away from the Sun.
  • (12 + 4): 10 = 1.6 would be the distance to the Sun from the planet Mars (240 million km). Real data: Mars is located an average of 227,940,000 km away from the Sun.
  • (24 + 4): 10 = 2.8 would be the distance to the Sun from planet XXXXX (420 million km). Real data: NO planet had been detected 420 million km away from the Sun.
  • (48 + 4): 10 = 5.2 would be the distance to the Sun from the planet Jupiter (780 million km). Real data: Jupiter is located an average of 778,830,000 km away from the Sun.
  • (96 + 4): 10 = 10.0 would be the distance to the Sun from the planet Saturn (1,500 million km). Real data: Saturn is located an average of 1,429,400,000 km away from the Sun.
  • (192 + 4): 10 = 19.9 would be the distance to the Sun of the planet Uranus (2.985 million km). Real data: Uranus is located an average of 2,870,990,000 km away from the Sun.
  • (384 + 4): 10 = 38.8 would be the distance to the Sun of the planet Neptune (5.820 million km). Real data: Neptune is located an average of 4,504,300,000 km from the Sun.

Everything fitted together well, except that no astronomer could find the fifth planet predicted in the Titius-Bode formula.

Planets
Planets of the solar system. Credit: Wikipedia.

When William Herschel discovered Uranus in 1781, he greatly increased astronomers’ enthusiasm for finding the fifth planet.

In 1791, the Hungarian astronomer, Baron Franz Xaver von Zach, Director of the Seeberg Observatory, in Gotha, Germany, organized a group of 24 astronomers, dedicated to the objective of preparing a systematic search for the so-called “lost planet“.

Among five groups of astronomers they divided the zodiac in search of the fifth planet, and combined their efforts.

They did not find the lost planet, but they did discover large asteroids in the search area.

Orbits
Orbits of the planets of the Sun. Credit: web “nationalgeographic.org”.

On January 1, 1801, the monk Giuseppe Piazzi, from Palermo, while reviewing a catalog of stars, found “something like a comet.”

Other astronomers calculated the orbit of the object, and assured that it responded to the location of the planet sought.

Orbit of Ceres.

Ceres orbits between Mars and Jupiter, in the middle of the asteroid belt, with a period of 4.6 years. The orbit is moderately inclined and slightly eccentric.

Orbits Ceres
Orbit of Ceres. Credit: Wikipedia.

Once the existence of this planet was confirmed, it was given the name of Ceres, the Roman goddess of agriculture, crops and fertility.

 Half a century later, in the 1850s, Ceres was listed as an asteroid. Indeed, it is in the area currently known as the “asteroid belt.”

Asteroids
Asteroid belt Credit: web americaspace.com

Origin and evolution of Ceres

Ceres is possibly a surviving protoplanet of the first stages of formation of the solar system, originating 4.57 billion years ago in the asteroid belt.

The geological evolution of Ceres, depended on the heat sources available during and after its formation.

Due to its small size, Ceres may have cooled off very soon, leading to the rapid cessation of all these geological remodeling processes.

The ice on the surface would have sublimated little by little, leaving behind different hydrated minerals such as clays and carbonates.

Today, Ceres appears to be a geologically inactive body with a surface sculpted only by impacts.

Ceres physical characteristics

Ceres has a diameter of 950 × 932 km and an area of ​​2,800,000 km².

It is the thirty-third largest known object in the solar system. Its mass is estimated to be one third of the total mass of the asteroid belt.

Ceres is the only object in the asteroid belt that is nearly spherical in shape.

The surface is composed of a mixture of water ice and various hydrated minerals such as carbonates and clays.

In early 2014, using data from the Herschel space observatory, it was discovered that there were several sources of water vapor in mid-latitudes, concentrated in an area no more than 60 km in diameter.

Ceres interior
Diagram showing the possible internal structure of Ceres. Credit: Wikipedia.

The interior of Ceres could be differentiated into a rocky core and an ice sheet, with an ocean under the ice sheet.

NASA’s Dawn probe entered orbit of Ceres on March 6, 2015. Photographing began as the spacecraft approached the dwarf planet.

The images had a resolution never before achieved, and showed a highly cratered surface and a thick layer of ice on a rocky core.

The new detailed images of Ceres, obtained from 385 km up, show several craters: Occator crater, Haulani crater and Piazzi crater.

Spaceships that have approached Ceres

NASA launched the mission called Dawn in September 2007 to visit Ceres and the asteroid Vesta.

Dawn
Artist’s rendering of the Dawn probe. Credit: NASA.

The Dawn mission entered Vesta’s orbit in July 2011, observing it for just over a year.

In September 2012, Dawn left Vesta and after a three-year journey, in March 2015, she reached Ceres.

Vesta
Vesta, Ceres and the Moon in full scale. Credit: wikipedia

In 2015, the Ceres Polar Lander project, linked to NASA, was announced.

 For its part, the Chinese Space Agency has among its projects the launch of a probe to Ceres, which would return with samples, but the mission is scheduled for the 2020s.