Instruction:

    We will be using the Exploring the Planets Software for this lesson.  This page will provide you notes and comments on what we cover in the program.  Any text that is underlined in Green is a button link in the Planets program for more information, and cannot be linked to from this web site.  Links to other sites that can be reached from this web site will be underlined in blue. Key terms will be in red.
 

Nasa News  Important Facts  (NASA Link)
 

1. Mariner 10 was launched in November 1973 and arrived in March 1974.  This is important because it is the only probe we have sent to Mercury.
2. We can't see the surface of Mercury from Earth because it is too close to the sun so it is lost in the suns glare.  We can also only see it in the morning and the evening so the haze of the thicker atmosphere blurs our view. (see sketch from class).
3. The most obvious feature on Mercury's surface is that it is completely covered by craters and craters within craters.
4. Mercury also has maria similar to the moon (though not as much).
5. A third terrain feature is giant cliffs caused by the cooling and shrinking of the crust.
6. Mercury has a weak magnetic field.  Strong magnetic fields are caused by molten cores, weak one are caused by frozen/solid cores.
7. Mercury has a very thin atmosphere.  So thin that it is nearly nonexistent.  Gases escape from the surface into space creating the very thin atmosphere.
8. Mercury has the greatest known temperature changes in the system from 476 C (872 F) on the sun side,  to -183 C (-198F) on the night side.
9. Mercury takes 59 days to rotate (spin) but 179 days from sunrise to sunrise. (see sketch from class.)
10. Mercury also takes 88 days to revolve around the sun.
11. Like all the rocky planets in the solar system, Mercury has 3 basic layers a core, a mantle and a crust.
12. Because we have only been to Mercury once and only for a short time we only have views from one side of the planet.

    Doctor Shoemaker;  Play this slide discusses why Mercury is important to study.  It shows us the impacts from early         planet formation.

Screen 2:

    The surface of Mercury looks much like the Moon.  It has many craters and looks much like the highlands of the moon, it also has smooth regions with maria.  Crater, vs Caldera (see sketch from class).  A crater has a floor that is below the natural surface and is usually surrounded by a rim.  A caldera forms in volcanoes and the floor of it is above the natural surface and usually forms as a depression without a rim.

    Compare to Earth:  Shows the size difference between the Earth and Mercury.

    Planet Processes, Impact Cratering:  This button shows a brief video of the formation of a crater.

At this point we switch to Impact Cratering in the Planet Processes Section of the Explore the Planets Software.  Click here for a link to the Impact Cratering notes

Screen 3:

    Like the Moon, Mercury has giant Multi Ringed Basins The large one on Mercury is called the Caloris Basin. It is 1300 km (800 miles) across.  The surrounding plains are covered with maria.

Screen 4:

    Wrinkle Ridges are also found on Mercury and on the Moon and Mars.  Wrinkle ridges form on lava flows and are probably due to tectonic forces.

Screen 5:

    Another terrain feature found on Mercury is fault scarps.  As Mercury cooled it contracted.  As it got smaller the surface buckled forming the fault scarps.

Screen 6:

    On the other side of Mercury from the Caloris Basin is an area of jumbled bumpy terrain known as weird terrain.

Screen 7:

    The weird terrain seems to be because of the Caloris Basin impact.  It may have been caused by the shock wave that rippled around the surface of Mercury and met on the back side.  The shock waves/seismic wave caused massive quakes which jumbled the terrain.

Screen 8:

    Large impacts caused lava flows which filled in the basins and floors of large craters forming maria.

Screen 9:

    Another view of the variety of craters.

Screen 10:

    Mercury has a density of 5.43 g/ml.  This means Mercury has a core larger than Venus and Mars giving it added weight.

Screen 11:

    Mercury also has a crust but we do not know how thick it is.

Screen 12:

    Sumary:  Except for meteor impacts Mercury is geologically inactive and probably has been for nearly 4 billion years.