Most asteroids are irregular, rocky chunks of matter which orbit the Sun. Until 2006, Ceres was considered to be the largest asteroid with a diameter of about 600 miles (960 km). It was not its size that changed its classification, instead other physical features were the deciding factors that boosted the hunk of rock into a newly formed category called dwarf planets.
See PLUTO DEMOTED for more information about the promotion of Ceres and the demotion of Pluto.
Discover for Yourself
How does the dwarf planet, Ceres, compare in size to the Earth’s Moon?
- Use a pencil and ruler to make two dots on a 12-inch square piece of poster board (card stock will work). Make one dot in the center of the poster board piece, which will be 6 inches from the edges. Make the second dot 3 inches from the first dot.
- Using a drawing compass, draw a circle with a 6-inch radius. The center of this circle will be the dot in the center of the poster board.
- Use the pencil and ruler to draw a line across the paper through the center dot. Label the line Moon- 2,200 miles (3,520 km).
- Repeat steps 2 and 3 using the second dot as the center of a circle with a 1 ½ -inch radius. Label the line Ceres, 600 miles (950 km). This celestial body is big, but not as big as the Earth’s moon, which has a diameter of about 2,200 miles (3,520 km). In this activity, the scale used for the models is 1 inch (2.5 cm) = 183 miles (293 km).
- Compare the size of the two circles. Notice how much smaller Ceres is in comparison to the Earth’s Moon, which is smaller than Earth.
Just for Fun!
Some of my books have been translated into different foreign languages. The following experiment is taken from 204 Sticky, Gloppy, Wacky & Wonderful Experiments, which has been translated into several languages, including Chinese.
The diagram shown has Chinese labels. Can you find the symbol for the kilometer (km)?
Top photo by goldenrectangle