Mercury is the second smallest planet; only Pluto is smaller. In fact, Mercury is not much larger than our moon. In this animation, you can find out how Mercury "sizes up" to Earth or any other planet. The first two planets that show up on the screen when you open this animation are Earth and Mercury. At the top of the screen, students can choose what planets they want to compare. At the bottom of the screen, students can see the dimensions for each planet as well as how they compare in size.
This animation was created before scientists in the International Astronomical Union voted for a new definition of a planet, which effectively removed Pluto from the list. So, Pluto is included in this animation. You may want to alert students to this fact. You also could use this as an opportunity to discuss with your students how scientists reach these kinds of decisions and what constitutes a planet.
