Overview
This lecture focuses on the planet Mars, covering its red coloration, geological activity, surface features, and the differences between its northern and southern hemispheres.
Mars and Its Red Color
- Mars is known as the Red Planet due to the iron in its soil and rocks.
- The red color comes from iron oxide, which is rust formed when iron reacts with moisture.
- Similar red soils exist on Earth, such as Georgia clay.
Cratering and Geological Activity
- Mars has fewer craters than Mercury, indicating past geological activity, mainly from volcanoes.
- Mars has more craters than Earth or Venus, showing it was less geologically active than those planets.
- Mars lost its internal heat faster than Earth and Venus because it is smaller.
- Most Martian volcanoes are now extinct, with the last eruptions occurring 20-200 million years ago.
- Occasional Mars quakes (similar to earthquakes) still occur, but Mars does not have plate tectonics.
Surface Features and Hemispheric Differences
- Mars's southern hemisphere (southern highlands) has many craters and higher elevation.
- The northern hemisphere (northern lowlands) is smoother with fewer craters and lower elevation.
- The crust is thicker in the south and thinner in the north.
- Volcanoes remained active longer in the north due to the thinner crust allowing lava to erupt as the planet cooled.
- Mars is overall flatter than Earth because it lacks plate tectonics, so there are no major mountain ranges.
Key Terms & Definitions
- Iron oxide — Chemical compound (rust) giving Mars its red color.
- Crater — Bowl-shaped depression caused by impacts.
- Geological activity — Processes like volcanism that shape a planet's surface.
- Plate tectonics — Movement of large crustal plates seen on Earth, not present on Mars.
- Mars quake — Seismic event on Mars, similar to an earthquake.
- Northern lowlands — Smooth, lower-elevation region of Mars with few craters.
- Southern highlands — Rough, higher-elevation region with many craters.
Action Items / Next Steps
- Review the characteristics and differences between Mars’s hemispheres.
- Prepare for discussion on Martian polar ice caps in the next class.