Of all of the dwarf planets that have been identified and defined, Ceres is the closest dwarf planet to the sun.
It’s located between the orbits of Jupiter and Mars in the asteroid belt and at 50 mi/950 km in diameter, is the smallest of the known dwarf planets.
We know a lot more about Ceres thanks to the Dawn spacecraft that arrived in 2015.
Ceres was the first dwarf planet to ever be visited by a spacecraft. For many years, this little object was called an asteroid and the information that Dawn sent back told scientists that it is very different from the rocky neighbors that are around it.
Ceres makes up 25% of the total mass of the asteroid belt, yet Pluto is still fourteen times more massive.
Discovered By: Giuseppe Piazzi
Date Discovered: January 1, 1801
Diameter: 950 km
Mass: 8.96 × 10^20 kg (0.01 Moons
Orbit Distance: 413,700,000 km (2.8 AU)
Orbital Period: 1,680 days (4.6 years)
Surface Temperature: -105 degrees C
Objects that are as far away as the dwarf planets presented a major challenge to early astronomers. They didn’t have the kind of sophisticated telescopes that we use today and instead had to rely on mathematical deductions.
On January 1, 1801, Giuseppe Piazzi, a Sicilian astronomer, discovered what he thought was a planet and named it Ceres, for the mythical Roman goddess of corn and harvests. Ceres is the source name for our word of “cereal.”
Within ten years, an additional four new objects were found to be in the same area as Ceres and the astronomers thought that all of these were also planets.
It took over 50 years before additional objects were found to be scattered between Jupiter and Mars and the asteroid belt was defined. At that time, Ceres was demoted to being just an asteroid.
Ceres was promoted to a dwarf planet in 2006 and couldn’t achieve the status of “planet” because it hadn’t cleared its neighborhood of debris.
Some scientific sources still list Ceres as an asteroid, even though it has officially been given the classification of dwarf planet.
In 2015 the IAU approved naming the features of Ceres for mythological agricultural gods and spirits.
It’s believed that Ceres was formed 4.5 billion years ago during the time when the rest of our solar system was forming. Gravity pulled dust and gas in so that it eventually came together to form the dwarf planet.
Scientists call Ceres an “embryonic planet” because it began to form but never finished the process. They believe this happened due to the strong gravity of Jupiter that had an effect on Ceres.
Nearing 4 billion years ago Ceres settled into its current location and orbit between Jupiter and Mars, along with a lot of other leftover objects from forming the planets.
Surface and Structure:
All of the identified dwarf planets except Ceres are located in the outer areas of the solar system in the Kuiper Belt. Ceres is the only one in the inner solar system regions.
Although it is the smallest of all of the dwarf planets, it’s the largest object found so far in the Kuiper Belt. Ceres makes up one third of the mass of the asteroid belt, even though it’s only 590 mi/950 km across.
Ceres is different than the other objects in the asteroid belt in that it has a spheroid shape, rounded, with an equator that has a bulge. Scientists theorize that at one time Ceres might have had an ocean and possibly even an atmosphere.
Ceres is actually more similar to our terrestrial planets of Mercury, Venus, Earth, and Mars than it is to its neighbors that are asteroids.
It’s less dense than the terrestrial planets but it shares the same kind of layered interior, even though the layers of Ceres aren’t defined very clearly. Scientists believe that Ceres has a solid core and a 25% water ice mantle that could contain more water than Earth has.
The crust of Ceres is dusty and rocky with a lot of deposits of salt. The salt isn’t like the table salt that we use (sodium chloride), but are made up of different elements such as magnesium sulfate.
The surface is also peppered with a lot of young, small craters. None of the craters are bigger than 175 mi/280 km.
Scientists think this abundance of young, small craters may be due to layers of ice below the surface that act as a resurfacing process and erased the larger craters.
Inside some of the craters on Ceres are areas that are always in shadows. It’s thought that without any direct sunlight these may be “cold traps” that have held water ice for a long time.
In 2015, the Dawn spacecraft was the first probe to orbit two solar system bodies. First it went to the asteroid Vesta and then over to Ceres.
Dawn found that Ceres had a dull gray surface and using spectral analysis found the presence of a type of graphite called “graphitized carbon.”
As the spacecraft came in closer to Ceres it also found a bright spot on its surface, and then later found 130 other spots of varying brightness.
The spots ranged from the kind of dull sheen that you find in concrete to a completely startling bright of Earth’s ice floating in the oceans. The brightest area is along the Occator Crater which is 56 mi/90 km wide.
This region has the largest collection of bright spots on Ceres.At first scientists thought that the spots could be from ice volcanoes, but there is only one pyramid-shaped mountain that rises from Ceres’ surface at 21,120 ft/6,437 m and it doesn’t show any volcanic or geologic activity.
Scientists are unsure how the mountain formed.Additional research of the bright spots found that they were made up of hydrated magnesium sulfate, the same material as our Epsom salt on Earth.
They also found that it contained sodium carbonate. On Earth, this forms due to the salts that are left from watery conditions under the crust. A majority of the bright spots are near craters so it could be that the spots are formed due to impacts.
The surface of Ceres might appear as a dull, dry gray, but scientists believe that it may have had a liquid ocean in its past.
The Dawn spacecraft used the bulk of Ceres to map its gravity and the observations shows that there are traces of an ocean just under the crust as well as signs that mantle is muddy below the surface.
Doing the math, scientists have estimated that at least 25 percent of the density of Ceres is due to water. Dawn confirmed a long held theory that Ceres hid an either frozen or liquid ocean.
It’s believed that the water-ice acts as a mantle on Ceres. The dusty, think crust is believed to be made up of rock and it’s thought that Ceres has an inner rocky core at the center.
Using spectral observations, it’s been revealed that the surface of Ceres contains clays that are iron-rich. When you add the fact that signs of carbonates have also been found on Ceres, it makes it one of the only objects in our solar system that contain these minerals other than Mars and Earth.
The formation of these minerals involves a process of water and heat, and carbonates are thought to be good indicators for potential habitability.
These findings were completely unexpected and scientists believe that some of the process that Ceres experienced in formation were more Earthlike.
It’s believed that when large objects impacted Ceres that they scooped out areas of the crust, slicing into the mantle of ice that was below and allowing the ice to remain closer to the surface. When the ice was heated by the sun it could transition from a solid to a gas.
The European Space Agency’s Herschel Space Observatory detected water vapor plumes in 2015 as they escaped Ceres at a rate of 13 lbs/6 kg per second. This is important because it’s the first proof of water on Ceres and in the asteroid belt.
In addition to the plumes, Dawn discovered that there are patches of minerals and ice on Ceres surface. A scientist found a patch of ice on the floor of the Juling Crater that was growing.
Another team of scientists found changes in the soil that are suspected to be tied to carbonates. They think that the same process at work on the Juling floor could be replenishing the water under the soil and partly condensing on the cold wall.
If the two processes are occurring it shows that water is available on the surface and that it produces mineralogical and geological surface changes.
Dawn also discovered areas on the surface that are organic-rich and determined that they are native to Ceres. The information from the spacecraft indicate that they were delivered from the interior to the surface.
Scientists are fascinated with the discovery of such a high concentration of organics. This adds to the theory that Ceres contains some of the key ingredients for life.
Atmosphere and Magnetosphere:
There is a very thin atmosphere on Ceres and it has evidence that it contains water vapor.
Scientists don’t think that Ceres has a magnetosphere.
Rotation and Orbit:
Ceres has one of the shortest days in the solar system. It makes a rotation every nine hours and it takes 1,682 Earth days (4.6 Earth years) to make a full trip around the sun.
Ceres also has only a four degree tilt on its axis of rotation and this means that it turns almost perfectly upright which doesn’t allow it to have seasons like other titled objects do.
The patches of water and ice on the surface may experience a change due to this minor tilt but it would take 24,500 years to go through any alterations. It would cause dramatic changes in the craters that hide water.
Around 14,000 years ago Ceres’ tilt was at its maximum and there were large areas where ice could hide throughout the shift.
Could Life Exist?
Ceres is considered to be one of the few locations in our solar system that scientists are indicating might harbor life. Ceres has an abundance of water as well as other organic chemicals.
If life was found on Ceres it would be very small microbes similar to the bacteria that we have on Earth. Even if there isn’t existing life today, scientists think that there might have been in the past.
- Due to the low mass and closer location, scientists are looking at Ceres as a potential site for a launching point or manned landings in the future.
- Ceres contains a significant amount of ice and points in the direction that the early solar system may have played a role in bringing water to Earth.
- Ceres was the first “asteroid” to be discovered and in 1801, Giuseppe Piazzi thought that it was a planet.
- Ceres may have been the Roman goddess of harvests and corn but she was also the patron goddess of Sicily.
- In 1803, the element cerium was named after the dwarf planet of Ceres. Cerium is one of the most abundant of rare-Earth metals.
- In 2014 and 2015, the Dawn spacecraft found two incredibly bright spots on Ceres inside a crater. Scientists suspect they may be due to volcanic activity even though they haven’t seen evidence of such.
- The bright spots on Ceres continue to be a mystery to scientists.
- Ceres stands out among other asteroid belt objects because it’s round due to having a more powerful gravity.
Astronomers had discovered a total of 62 objects between Jupiter and Mars by 1860. In 1863 astronomers named them asteroids and called the area of discovery the asteroid belt.
This remained the status quo for 140 years. In 2006, astronomers made series a dwarf planet.
In 2015 the Dawn spacecraft orbited Ceres and studied its surface and composition.
1801: While looking for a star, Giuseppe Piazzi discovers Ceres and calls it a planet.
1802: John Herschel created the term “asteroid.”
1850: Alexander von Humboldt is the first to use the term “asteroid belt.”
1863: Astronomers accept Ceres to be classified as an asteroid.
2006: Ceres is re-classified as a dwarf planet.
2007: The launch of the Dawn spacecraft.
2015: The spacecraft Dawn arrives at Ceres and becomes the first spacecraft to orbit a dwarf planet.
Facts Ceres Dwarf Planet for Kids:
- Ceres is the only dwarf planet without any moons.
- Ceres loses 6 kg of its mass every second with the release of water vapor steam in its plumes.
- Ceres has a lot of ice, minerals, and water and is being considered as a potential location for human colonization.
- At one point, astronomers called Ceres and other objects like it “minor planets.”