1. Chapter 14 Section 4 What are the solstices and equinoxes?
Objective:
Define solstice and equinox

2. Key Terms
perihelion: point in a planet’s orbit at which it is closest to the Sun
aphelion: point in a planet’s orbit at which it is farthest from the Sun

3. Key Terms
solstice: day of the year that Sun reaches its highest or lowest point in the sky
equinox: day the Sun shines directly on the equator

4. Near and Far
During the year, the distance between Earth and the Sun changes. Earth is at perihelion in early January. Earth and the Sun are then about 147 million km apart. The Northern Hemisphere has winter. In early July, Earth is at aphelion. This distance is about 152 million km. Yet, this is summer in the Northern Hemisphere. The seasons do not depend on how far Earth is from the Sun.

5. NAME
During which season is the Northern Hemisphere closest to the Sun?

6. The Solstices
The beginning of the summer and winter seasons is marked by a day called a solstice. The word solstice means “Sun stop.”

7. The Solstices
In the Northern Hemisphere, the first day of summer is on or about June 21. The Sun seems to travel in its highest path across the sky. This day is called the summer solstice. On this day, Earth is very close to aphelion. The North Pole has 24 hours of daylight. At the same time, the South Pole points away from the Sun. The South Pole has 24 hours of darkness. Winter begins on this date in the Southern Hemisphere.

8. The Solstices
The first day of winter in the Northern Hemisphere is on or about December 21. This day is called the winter solstice. On the winter solstice, Earth is very close to perihelion. The North Pole points away from the Sun. The Sun seems to follow its lowest path across the sky. On this day, the South Pole has 24 hours of daylight.

9. 2. IDENTIFY
What day marks the first day of winter in the Southern Hemisphere?

10. The Equinoxes
Because of the tilt of the Earth’s axis, the Sun’s position relative to Earth’s equator is constantly changing. Most of the time, the Sun is north or south of the equator at solar noon. Two times during the year, the Sun is directly over the equator at solar noon.

11. The Equinoxes
The equinoxes mark the beginning of the spring and fall seasons. The spring, or vernal, equinox occurs around March 21. The fall, or autumnal, equinox occurs around September 21. During an equinox, there are 12 hours of darkness and 12 hours of daylight everywhere on Earth.

12. 3. NAME
On which days of the year does the North Pole have 12 hours of daylight and 12 hours of night?

14. Classwork CHECKING CONCEPTS
What is a day with 12 hours of daylight and 12 hours of darkness called?
What date marks the beginning of winter in the Northern Hemisphere?
Are the days longer or shorter in the Northern Hemisphere right after the autumnal equinox?

15. Classwork 4. Equinox means “equal night.” How many
hours of daylight and darkness are there
during the fall and spring equinoxes?

16. Classwork THINKING CRITICALLY
5. DESCRIBE: What is winter like in your area?
6. HYPOTHESIZE: On the winter solstice, the
North Pole 24 hours of darkness. How would
this affect your life that day if you lived
there?