Seasons & Lunar phases Chapter 11 Lesson 1

Seasons are caused by two things Earth’s tilted axis. Earth’s orbit (revolution) around the sun.

Points in the same direction all year Earth’s Axis Tilted at 23 degrees Points in the same direction all year

Revolution vs. rotation Revolution around sun causes years Rotation on axis causes day and night

Equinox-sunlight shines equally on the Northern Hemisphere and Southern Hemisphere. Solstice-Sunlight at a max in one hemisphere and a minimum in the other (shines unequally).

June solstice Around the 21st –begins in summer The Northern Hemisphere gets more sunlight. The North Pole is tilted towards the sun.

Around the 21st – begins in the winter. December Solstice Around the 21st – begins in the winter. The Southern Hemisphere gets more sunlight. The North Pole is tilted away from the sun.

Equinoxes September Equinox- around 21st- begins fall March Equinox-around 21st-begins spring The Northern Hemisphere and Southern Hemisphere get equal sunlight Sunlight is centered on the equator.

The Moon’s Orbit One revolution around Earth = 28 days. Rotates on its axis at the same rate as it orbits so the same side is always facing Earth. Gravitational force causes the moon to orbit Earth; this force depends on their masses and how far apart they are from each other.

Far side of the moon: side never visible from Earth. Near side of the moon: side is always visible from Earth.

Lunar Phases Waxing Moon = growing Moon Waning Moon = shrinking Moon Gibbous Moon = Moon that is more than half lit Crescent Moon = Moon that is less than half lit New Moon = near side is dark Full Moon = near side is fully lit

Lunar Phases

Eclipse: occurs when a shadow makes the Sun or Moon look dark

Lunar Eclipse Occurs as the Moon passes into the Earth’s shadow A total eclipse occurs once the Moon moves into Earth’s Umbra (the darkest part of Earth’s shadow)

Solar Eclipse Occurs when the Moon passes directly between the Earth and Sun and the Moon casts a shadow on Earth