The planet Mars is 4.6 billion years old. It's a sphere, and the crust is uniformly exposed to space. Yet, the surface of the planet appears to tell an inconsistent story. The Martian highlands (or the southern hemisphere) is littered with thousands of craters, but the Martian lowlands (or the northern hemisphere) is flat and smooth. Why are there obvious and clear differences in the amount of cratering on Mars from one region to another?
When comparing landscapes across Mars, we find significant variations in appearance. Some regions are almost crater-free, while others are practically covered with craters of all sizes. Why? Could impactors like meteors and meteorites preferentially fall in certain regions? Shouldn't we expect the surface of Mars to be uniformly cratered?
The goal of this lesson is to provide insight into what planetary scientists can learn about the ages of planetary terrains by analyzing crater patterns. By comparing the craters in the Martian highlands and lowlands, what might your study reveal?
This lesson is appropriate for students in grades 7-12.
Timeline
0:00 Introduction and materials
1:35 Select a area for analysis and outline craters
2:16 Count craters and measuring diameters
2:28 Plot a best-fit line for regional age
The written materials, images, and other teacher resources for this and other SMAP lessons are available free for educators here; bit.ly/SMAPSelectedLessons.
Saturday Morning Astrophysics at Purdue is one of the flagship programs from the Department of Physics and Astronomy at Purdue. SMAP is open to students from around the world, in grades 8-12. Check it out for details and see what you think; bit.ly/SMAPPurdue.
Thank you Mariana Aguilar, Purdue PhD student in Planetary Science, for the design and presentation of this lesson, and to Raymond Glowner for his helping hand.
The production, recording, and thumbnail design, for this video were provided Jonathan Sullivan-Wood.