Earth-Sun Relations: Seasons, Axial Tilt, and Solar Energy

When is Earth closest to the sun?

On the Perihelion (January 3)

When is Earth furthest from the sun?

On the Aphelion (July 4)

What causes the seasons on Earth?

The changing tilt of Earth's axis, not its distance from the sun.

What is the variance in Earth-sun distance?

3% variance.

On what plane does Earth orbit the sun?

The ecliptic plane.

What is the tilt of Earth's axis of rotation?

23.5 degrees from perpendicular to the ecliptic plane.

Where does Earth's axis point throughout the year?

It points in the same direction (toward Polaris) all year.

How does the orientation of Earth's axis change?

It changes relative to the sun as Earth orbits.

How does the axial tilt affect daylight hours?

The number of hours of daylight changes during Earth's orbit.

What happens to the energy received due to longer days?

More energy is received.

How does the axial tilt affect sunlight at a location?

It affects the directness of sunlight.

What is the sun altitude in June?

69.5 degrees.

What is the sun altitude in December?

22.5 degrees.

What occurs during the June solstice?

Maximum tilt of the northern hemisphere towards the sun.

What is the day length during the June solstice?

Longer day length in the northern hemisphere.

What occurs during the December solstice?

Maximum tilt of the southern hemisphere towards the sun.

What is the day length during the December solstice?

Shorter day length in the northern hemisphere.

What happens during the March and September equinoxes?

Neither hemisphere is tilted toward the sun.

What is the day length at all latitudes during equinoxes?

12 hours.

Where is the subsolar point located during equinoxes?

At the equator.

How does seasonality change with latitude?

It increases due to the annual range of sun altitude and day length.