Exercises 291might have come from such a study are to be found on the Web site in a file named
AirQual.dat in case you want to play with data.9.39 In 2005 an object was discovered out beyond Pluto that was (unofficially) named Xena and
now is called Eris. It is larger than Pluto but is not considered a planet—the new title is
“plutoid.” It is 96.7 astronomical units from the sun. How does such an object fit with the
data in Table 9.7.
9.40 In 1801 a celestial object named Ceres was discovered by Giuseppi Piazzi at 2.767 astro-
nomical units from the sun. It was called a dwarf planet, but those are now plutoids. If it
were classed as a planet, how would this fit with the other planets we know as shown in
Table 9.7?