LESSON 2: CERES AND MAKEMAKE

 Ceres

• Planet Type: Dwarf Planet
• Namesake: ROMAN GODDESS OF HARVESTS
• Moons: 0
• Distance from the Sun: 2.8 AU

A 3D model of Ceres, a dwarf planet in the main asteroid belt between Mars and Jupiter. Credit: NASA Visualization Technology Applications and Development (VTAD)› Download Options

Introduction:

Ceres is the largest object in the asteroid belt between Mars and Jupiter, and it is the only dwarf planet in the inner solar system. When Giuseppe Piazzi discovered it in 1801 it was the first member of the asteroid belt to be discovered. Ceres was the first dwarf planet to be visited by a spacecraft when NASA's Dawn arrived in 2015.

For many years, Ceres was classified as an asteroid, but it is now so much larger and different from its rocky neighbors that scientists classified it as a dwarf planet in 2006. Despite accounting for 25% of the total mass of the asteroid belt, Pluto is 14 times larger.

Namesake:

Ceres is named for the Roman goddess of corn and harvests. The word cereal comes from the same name.

Potential Life

Ceres is one of the few places in our solar system where scientists want to look for signs of life. Ceres has something that many other planets lack: water. Water is necessary for life on Earth, so it's possible that life could exist there if this ingredient and a few other conditions are met. If life exists on Ceres, it is most likely in the form of very small microbes similar to bacteria. If Ceres does not have life today, there may be evidence that it did in the past.

Size and Distance

With a radius of 296 miles (476 kilometers), Ceres is 1/13 the radius of Earth.Ceres is 2.8 astronomical units away from the Sun. One astronomical unit (abbreviated as AU), is the distance from the Sun to Earth. From this distance, it takes sunlight 22 minutes to travel from the Sun to Ceres.

Orbit and Rotation

Ceres takes 1,682 Earth days, or 4.6 Earth years, to make one trip around the Sun. As Ceres orbits the Sun, it completes one rotation every 9 hours, making its day length one of the shortest in the solar system.

Ceres' axis of rotation is tilted just 4 degrees with respect to the plane of its orbit around the Sun. That means it spins nearly perfectly upright and doesn't experience seasons like other more tilted planets do.

Formation

Ceres is classified as a "embryonic planet," which means it formed but did not complete. The strong gravity of nearby Jupiter prevented it from forming into a fully formed planet. Ceres settled into its current location in the asteroid belt between Mars and Jupiter about 4 billion years ago, among the leftover pieces of planetary formation.

Structure

Ceres resembles the terrestrial planets (Mercury, Venus, Earth, and Mars) more than its asteroid neighbors, but it is much less dense. A layered interior is one of the similarities, but Ceres' layers aren't as well defined. Ceres most likely has a solid core and a mantle of water ice. 

Ceres, in fact, could be made up of up to 25% water. Ceres, if this is correct, has more water than Earth. The crust of Ceres is rocky and dusty, with large salt deposits. Ceres' salts aren't like table salt (sodium chloride), but are made of different minerals, such as magnesium sulfate.

Makemake

• Makemake, which is slightly smaller than Pluto, is the second-brightest object in the Kuiper Belt as seen from Earth (while Pluto is the brightest).
• This dwarf planet takes about 305 Earth years to complete one orbit around the Sun.

Makemake was first observed in March 2005 by M.E. Brown, C.A. Trujillo, and D.L. Rabinowitz at the Palomar Observatory. Its unofficial codename was Easterbunny. Before this dwarf planet was confirmed, its provisional name was 2005 FY9. In 2016, NASA’s Hubble Space Telescope spotted a small, dark moon orbiting Makemake.

This Hubble image reveals the first moon ever discovered around the dwarf planet Makemake. The tiny satellite, located just above Makemake in this image, is barely visible because it is almost lost in the glare of the very bright dwarf planet. Hubble’s sharp-eyed WFC3 made the observation in April 2015. Credits: NASA, ESA, and A. Parker and M. Buie (SwRI)

Namesake

Makemake was named after the Rapanui god of fertility.

Potential for Life

The surface of Makemake is extremely cold, so it seems unlikely that life could exist there.

Size and Distance

• Radius: approx. 444 miles (715 kilometers)
• Makemake is 1/9 the radius of Earth. If Earth were the size of a nickel, Makemake would be about as big as a mustard seed.
• Makemake is 45.8 astronomical units away from the Sun. One astronomical unit (abbreviated as AU), is the distance from the Sun to Earth. From this distance, it takes sunlight 6 hours and 20 minutes to travel from the Sun to Makemake.

A 3D model of Makemake, a dwarf planet in the Kuiper Belt. Credit: NASA Visualization Technology Applications and Development (VTAD)› Download Options

Orbit and Rotation

Makemake takes 305 Earth years to make one trip around the Sun. As Makemake orbits the Sun, it completes one rotation every 22 and a half hours, making its day length similar to Earth and Mars.

Moons

Makemake has one provisional moon, S/2015 (136472) 1, and it's nicknamed MK 2. It is more than 1,300 times fainter than Makemake. MK 2 was seen approximately 13,000 miles from the dwarf planet, and its radius is estimated to be about 50 miles (80 kilometers).

Rings

There are no known rings around Makemake.

Formation

Dwarf planet Makemake is a member of a group of objects that orbit in a disc-like zone beyond the orbit of Neptune called the Kuiper Belt. This distant realm is populated with thousands of miniature icy worlds, which formed early in the history of our solar system about 4.5 billion years ago. These icy, rocky bodies are called Kuiper Belt objects, transneptunian objects, or plutoids.

Structure

Scientists know very little about Makemake's structure.

Surface

• It does appear to be a reddish-brownish color, similar to Pluto.
• Scientists have also detected frozen methane and ethane on its surface. In fact, pellets of frozen methane as big as half an inch (1 centimeter) in diameter may rest on Makemake's cold surface.

Atmosphere

Makemake may develop a very thin atmosphere, most likely made of nitrogen near perihelion – when it is closest to the Sun