SEASONS The tilt of the Earths axis causes

SEASONS

The tilt of the Earth’s axis causes the seasons. The Earth’s axis is tilted from vertical. 0 23. 5

Also, seasons change depending on the amount of sunlight reaching the Earth as it revolves around the Sun. The axis always points in the same direction in space.

Direct Light covers a smaller area and it is more intense (stronger). Indirect Light is spread over a larger area (scattered) and it is less intense.

During our summer the northern hemisphere is tilted toward the Sun. Summer solstice June 21 -22 Direct Sunlight The hemisphere that is tilted toward the sun receives more direct sunlight. The Sun rays are less scattered and temperatures are higher (warmer).

The hemisphere that is tilted toward the Sun has longer days and shorter nights. The Sun is visible for 24 hours in the Arctic Circle in June. Summer solstice June 21 -22

During our winter the northern hemisphere is tilted away from the Sun. Indirect sunlight Winter Solstice December 21 -22 We are receiving sunlight at an indirect angle. The sun rays are scattered and the temperatures are lower (cooler).

Direct Summer Solstice June 21 First day of Summer Longest day of the year Indirect Winter Solstice December 21 First day of Winter Shortest day of the year • Axis tilted toward Sun • Axis tilted away from Sun • Summer for 3 months • Winter for 3 months • Direct sunlight • Indirect sunlight • Longer days; shorter nights • Shorter days; longer • Warmer temperatures nights • Cooler temperatures

During fall and spring the Earth’s axis is parallel to the sun. Sunlight Vernal Equinox (Spring) –March 20 Autumnal Equinox (Fall) – September 22 The northern and southern hemispheres get equal amount of sunlight. Temperatures are mild.

Vernal Equinox March 20 First day of Spring Autumnal Equinox September 22 First day of Fall • Axis is parallel to the sun • Both hemispheres get equal amount of sunlight • Mild temperatures

March 20 Vernal Equinox Spins (rotates to the East) Direct Sunlight December 20 Winter Solstice Indirect Sunlight June 20 Summer Solstice September 22 Autumnal Equinox

• Involves one object • Spins around an axis (an imaginary line that goes down the center of an object)

The Earth and the Sun rotate around an axis. AXIS

Earth rotates on its axis (spins) every 24 hours.

Night Day Sun Rays Earth completes one Rotation (spin) on its axis once every 24 hrs

REV LUTI N • Involves two or more objects • Object moves around a fix point, usually another object • Object follows an orbit or pathway

Earth’s Complete Revolution (orbit) 365. 25 days

Moon’s Complete Revolution (orbit) 29. 5 days

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