The Orbits of Mercury and Earth. In this exercise you can use Starry Night Enthusiast™ to compare the orbits of Mercury and the Earth. Open Favourites  Solar System  Inner Planets  Inner Solar System...

The Orbits of Mercury and Earth. In this exercise you can use Starry Night Enthusiast™ to compare the orbits of Mercury and the Earth. Open Favourites  Solar System
 Inner Planets
 Inner Solar System and click on the Stop () button to stop time. From your viewpoint about 5.3 AU from the Sun, you are looking down at the inner planets at an angle to the ecliptic plane. Open the Find pane and click on the boxes on either side of the names of Venus and Mars to remove the orbits and labels of these planets from the view. Use the Location Scroller (Hold down the Shift key while holding down the mouse button and moving the mouse) to move around the Sun on the surface of a sphere of radius 5.3 AU and examine and compare the orbits of Mercury and Earth. (a) Place yourself directly above the Earth’s orbit. (Hint: The orbital path of Earth will appear to be uniformly bright when you are in this position). Which of the orbits of Earth and Mercury is closest to circular? (b) Use the Location Scroller to place yourself in the Earth’s orbital plane (i.e., with the ecliptic edge-on). Are the orbits of Earth and Mercury in the same plane? If not, measure the angle between these two orbital planes by zooming in on the Sun to a field of view about 10° wide and tracing the two orbital planes onto tracing paper or transparent film with a soft felt-tipped pen.