1. Mercury Part 2, The Planet

2. Mercury has no Atmosphere
Why?
1. Gravity is too weak,
so escape velocity is low
2. At the equator heat from the Sun causes gas molecules to move faster than escape velocity …so they leave!

3. Surface Temperature
Mercury has the greatest change of temperature of any planet
Daytime High: 700°K (800°F)
Nighttime Low: 100°K (-280°F)
Because It has the …
1. Heat: It is closest to the Sun
2. Time: It has a very long solar day (176 Earth Days)
3. No Atmosphere to hold onto the heat

4. Surface Features Craters: Cover Mercury..like the Moon
But many are filled with lava plains, like lunar maria.

5. The Caloris Basin The largest crater is the Caloris Basin
1300 km across!

6. Scarps Long Cliffs cris-cross the surface
created by shifts in the crust as it cooled

7. The “Weird Terrain”
This “hummocky” terrain on the opposite side of Mercury from the Caloris Basin
Was probably caused when shockwaves from the impact at the basin met

8. Mercury’s Interior
Mercury probably has a core which is larger compared to the planet than Earth’s.
The Crust and Mantle are relatively thin.
As no probes have landed there we can’t be sure