Cornell Notes 1.2 Seasons September 13, 2017 – Page 15

Essential Question Why do seasons happen?

Big Idea Seasons happen because the Earth tilts and one half receives more direct sunlight than the other at different points in its orbit around the Sun

What doesn’t happen Seasons are NOT about distance from the Sun In fact, the Earth is closer to the Sun in January than it is in July Also, seasons are different around the globe When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere

The Earth Tilts The Earth doesn’t just stand straight up and down Its axis tilts 23º to the North (towards the North Star.) As it orbits, it keeps tilting in the same direction So while the North Pole always points to the North Star, it changes relative to the Sun

Earth’s Tilt in Its Orbit North -------------->

Summer Solstice Summer Solstice was June 20 in 2017 The Earth is to the South of the Sun The Northern Hemisphere gets more direct sunlight, so it’s Summer there – and the longest day of the year The Southern Hemisphere gets less direct sunlight, so it’s Winter there – and the shortest day of the year

Autumnal Equinox Autumnal Equinox will be September 22 in 2017 The Earth is to the East of the Sun The Two Hemispheres get equal amounts of direct sunlight, so it’s Fall in the North and Spring in the South The days and nights are of equal length

Winter Solstice Winter Solstice will be December 21 in 2017 The Earth is to the North of the Sun The Northern Hemisphere gets less direct sunlight, so it’s Winter there – and the shortest day of the year The Southern Hemisphere gets more direct sunlight, so it’s Summer there – and the longest day of the year

Spring Equinox Spring Equinox was March 20 in 2017 The Earth is to the West of the Sun The Two Hemispheres get equal amounts of direct sunlight, so it’s Spring in the North and Fall in the South The days and nights are of equal length

Earth’s Tilt in Its Orbit North --------------> Spring Equinox Summer Solstice Winter Solstice Autumn Equinox

At the Poles During the Winter – the sun shines all day on the South Pole and not at all on the North Pole During the Summer– the sun shines all day on the North Pole and not at all on the South Pole So the North and South Poles have six months of Day and Six Months of Night (From Equinox to Equinox) The Sun shines more directly on the Equator all year round, that’s why it’s warmer there (and days are more even)