Why do we have seasons?

• Because of the tilt on our axis!!!!!!!

• NOT our distance to the sun

SUMMER

WINTER

Dates to Remember

Angle of Incidence

What is the difference between rotation and revolution?

Rotation = spinning around its axis• Earth’s Period of Rotation = 24 hours– Causes day and night (rise and set of sun, moon, and

stars)

Revolution = orbiting an object• Earth’s Period of Revolution = 365 days 6 hours 9

min– Causes yearly changes (seasons, variations in number of

daylight hours) because of our tilt

Exit Questions

• 1. Axis A. 23.5 degrees• 2. Perihelion B. closest to the sun• 3. Revolution C. 1 day (24 hours)• 4. Aphelion D. 1 year (365 ¼ days)• 5. Rotation E. farthest from the sun• 6. Tilt F. imaginary line that runs

from pole to pole around which we spin

The MOON

Lunar Motions

• Moon Phase Cycle (Synodic Month) = 29 ½ days

• Moon Revolution (Sidereal Month) = 27 1/3 days

• Moon Rotation = 27 1/3 days

• Daytime Temperature = 127 degrees Celsius

• Night Temperature = -173 degrees Celsius

Properties of the Moon

• Diameter = 3,475 km (1/4 the diameter of the Earth – unusually large)

• Density = 3.3 g/cubic centimeter (Earth’s is 5.5)

• Gravity = 1/6th of the Earth

• Moon has no atmosphere or water

Lunar Surface

Marias (seas) = dark, relatively smooth areas, ancient lava flows

Regolith – layer of dust on the lunar surface that formed from the meteorite impacts

Highlands = light colored, mountainous areas that are heavily cratered

Formation of the Moon

Impact Theory:• A mars sized object collided

with the Earth

• The material ejected from the surface of the Earth became the Moon.

• This explains…• Why does the Moon have a

much lower density than the Earth?

• Why does the Moon not have any water?

Moon motion model lab

• Perigee – moon closest to the Earth

• Apogee – moon farthest from the Earth

Mimas (saturn)

Titan (saturn)

Triton (neptune)

Europa (jupiter)

Miranda (Uranus)

Io (Jupiter)

• Phobos and Deimos (Mars)

Our Moon

More Moon Fun

Distance to the Moon

• Perigee – 221,519 miles

• Apogee – 252,712 miles

• Avg. Distance - 237,700 miles

Moon Phases

• Sidereal Month – moon revolution – 27 1/3 days

• Synodic Month (moon phase cycle) – 29 ½ days

• ALWAYS STARTS WITH A NEW MOON

Moon Phases

• The changing appearance of the moon as seen from Earth

• CAUSED BY…the changing position of the moon relative to the Earth and the Sun

Moon Phase Cycle

Go Over the last unit test

Do Now: Identify Each Moon Phase

1) _________________2) _________________

4) _________________3) _________________

Moon Phase Calendar Activity

Solar EclipseSun-Moon-Earth

Moon is 1/400 the size of the sun and 1/400 the distance to the sun making them look identical in size

Umbra – complete shadow

Penumbra – partial shadow

Lunar Eclipse

SUN-EARTH-MOON

Tides

• Periodic rise and fall of sea level

• High Tides occur every 12 hours and 25 minutes (24 hour 50 minute cyle)

• Direct Tide – moon pulls the oceans toward it

• Indirect Tide – less pull on opposite side causes another bulge

TIDES

• Spring Tide – cumulative gravitational pull of the moon AND sun on our oceans. Tides are much Higher and lower than usual. Occurs every Full and New Moon

TIDES

• Neap Tides – occur during 1st and 3rd quarter moon phases in which the moon is at a right angle to the Earth compared to the sun. Tides are much LESS strong