distances and motions of the The relative sizes, distances and motions of the Sun, Earth and Moon (Lesson 2)

SEM Scale Materials List Make sure the following is in your bin. Let Mr. Abe know right away if something is missing. A globe 2 Styrofoam spheres (one larger, one smaller) 1 white acrylic bead 1 blue marble 1 flashlight 1 ruler

Diameters Sun = 1,392,000 km Earth = 12,756 km Moon = 3500 km (109 Earths wide) (391 Moons wide) Earth = 12,756 km Moon = 3500 km (¼ Earths wide)

Diameters (with 12 cm Earth) Sun ≈ 13 m (109 Earths wide) (391 Moons wide) Earth ≈ 12 cm Moon ≈ 3 cm

Distances Earth to Moon = 384,000 km Earth to Sun = 150,000,000 km Earth to Sun =100 cm Earth to Moon = 1/4 cm

Distances with our Model Earth to Moon = 3.61 meters Earth to Sun = 1.41 km (almost to Skyline High School) Earth to Sun =100 cm Earth to Moon = 1/4 cm

Relative Appearance The Sun is about 400x bigger than the Moon but is also about 400x farther away. This makes the Sun and the Moon appear to be the same size from our perspective.

Geometry and Relative Motions of the SEM System

Why is our sense of scale so skewed? Why would they show the SEM in this way?

Rotation and Revolution (Page 19) Rotation is the spin of the Earth on its axis. 1 rotation of the Earth is one day (24 hours). Revolution is the orbit of the Earth around the Sun. 1 revolution of the Earth is one year (365 ¼ days).

Leap Year/Leap Day Since each year has 365 and ¼ day every 4 years there is an extra day added to the calendar. This is called leap day (February 29th).