What causes seasons?

• The tilt of the Earth on its axis• The 23.5° tilt is caused by the interaction

between the Moon and the Earth

Summer Solstice

• The Sun’s rays hit the Tropic of Cancer at a 90° angle

• June 21st or 22nd • Longest day of light for the Northern

Hemisphere

Summer Solstice

• What happens in the Southern Hemisphere?

Winter Solstice

• The Sun’s rays hit the Tropic of Capricorn at a 90° angle

• December 21st or 22nd • Shortest day of light for the Northern

Hemisphere

Winter Solstice

• What happens in the Southern Hemisphere?

Autumnal Equinox

• The Sun’s rays hit the Equator at a 90° angle• September 22nd or 23rd • Equinox means “Equal Night”• Hours of daylight = darkness• Fall

Vernal Equinox

• The Sun’s rays hit the Equator at a 90° angle• March 21st or 22nd

• Equinox means “Equal Night”• Hours of daylight = darkness• Spring

Precession

• The axis of the Earth continual points towards the North Star.

• What does this mean for the Southern Hemisphere?

Precession

• The slow circular motion of the Earth;s axis as it turn in space that traces a circle in space every 26 thousand years