The Sun’s Annual PathOn the equinoxes, Sun is on the celestial equator.

Both hemispheres receive the same amount of sunlight!

Sun on March 21

Sun on September 21

The Sun’s Annual PathOn the solstices, Sun is farthest from the equator.

One hemisphere receives more sun than the other.

Sun on Dec. 21

Sun on June 21

The Changing Path of the SunAs the Sun moves north & south along the ecliptic,

the Sun’s path across the sky also changes.

North celestial

pole

The Changing Path of the SunOn the equinoxes, the Sun rises exactly east and

sets exactly west.

North celestial

pole

The Changing Path of the SunOn June 21 (northern summer solstice), Sun lies

the most north of the celestial equator.

North celestial

pole

The Changing Path of the SunAnd the Sun reaches its highest point in the sky.

North celestial

pole

The Changing Path of the SunOn Dec. 21 (northern winter solstice), Sun lies the

most south of the celestial equator.

North celestial

pole

The Changing Path of the SunAnd the Sun reaches its lowest point in the sky.

North celestial

pole

Which pair of changes during the year are the principal causes of the seasons on Earth?

I. the changing Earth-Sun distanceII. the changing height of the Sun at noonIII. the changing length of daylightIV. the changing rotation of Earth relative to the stars

A. Items I and II

B. Items I and III

C. Items II and III

D. Items I and IV

You observe the Sun at its lowest position above the horizon at noon-time. On the next day, you find the Sun has a slightly higher altitude.

What day is it?

A. The day after spring equinox

B. The day after summer solstice

C. The day after fall equinox

D. The day after winter solstice

Sunlight & SeasonsIf we imagine Earth as tilted, the same effects are still relevant. Which hemisphere is receiving more sunlight and experiencing summer?

Sunlight & SeasonsSix months later, which hemisphere is receiving more sunlight and experiencing summer?

Which hemisphere is experiencing winter?

A. A only

B. B only

C. Both A and B

D. Neither A nor B

How many x’s are experiencing summer?

A. One B. Two C. Three D. Five

Extreme SeasonsWhat would it be like on a planet completely tilted on its side (for example, planet Uranus)?

N S N S

N S

N S