1. Planetary Orbits and Rotation

2. Warm Up ???
Planets travel around the Sun along paths called orbits. What shape do you believe a planetary orbit consists of?
Does the Earth’s distance from the sun ever change as it follows its orbital path around the sun?
What causes seasons on earth (Winter and Summer)?

3. Planetary Orbits
The planets do not orbit the sun in a circular pattern.
Johannes Keplar (German mathematician, 1600’s) discovered that the planets orbit the sun in the shape of an ellipse. Earth
Sun Foci (#2)
The Sun is not at the center of this ellipse but is slightly offset to one side. It is one of two foci.

4. Planetary Orbits

5. Earth’s Tilt and Rotation
Earth’ axis is tilted 23.5 degrees.
Thus, at times in the year the northern and southern hemispheres are tilted toward the sun.
The hemisphere that is tilted toward the sun receives more hours and more direct sunlight during the day.

6. Season’s, Solstices, and Equinoxes
The solstice is the day when the sun reaches it’s greatest distance North or South of the equator.
Summer Solstice is longest day of year
Winter solstice shortest day of year
Earth is closest to the sun during the winter solstices for the northern hemisphere.

7. Season’s, Solstices, and Equinoxes
An equinox occurs when the Sun is directly above Earth’s equator.
Most of the year the sun is north or south of the equator but two times a year it is directly above it
These times are called fall and spring Equinoxes.

8. Tilt and Temperature
After performing the tilt and temperature lab answer the following question to check your understanding.
Why do more direct rays of sun (closest to 90 ̊̊) create higher temperatures or more heat?