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Transcript of Seasons
How do we define up and down in space? What would "vertical" mean? For the Earth, we can think of vertical as straight up and down with respect to the plane in which the Earth orbits the Sun (called the ecliptic).
Earth's rotational axis points in the same direction relative to the stars, so that the North Pole points towards the star Polaris. Think of the Earth as a spinning top, tipped over to one side. Over very long time periods (thousands of years) the direction of Earth's axis slowly changes due to precession.
The Earth rotates around once in 24 hours - that's a rate of 1000 miles per hour!. The time it takes for the Earth to rotate completely around once is what we call a day. It's Earth's rotation that gives us night and day.
The combined effect of the Earth's tilt and its orbital motion result in the seasons. X Haha. Yea. Too complex! Day and night is caused by the Earth's rotation on it's axis. When it does one complete rotation, it is one full day. Earth takes approximately 365.25 days to complete one revolution around the Sun in a slightly elliptical orbit with the Sun at one focal point of the ellipse. Ranging between the extremes of perihelion (closest approach) in January and aphelion (most distant orbital position) in July, Earth's orbital distance from the Sun ranges from approximately 91.5 to approximately 94 million miles (14751 million km), respectively. Although these distances seem counter intuitive to residents of the Northern Hemisphere who experience summer in July and winter in January, the seasons are not nearly as greatly affected by distance as they are by changes in solar illumination caused by the fact that Earth's polar axis is inclined 23.5 degrees from the perpendicular to the ecliptic (the plane of the solar system through or near which most of the planet's orbits travel) and because the Earth exhibits parallelism (currently toward Polaris, the North Star) as it revolves about the Sun. X Long story short: A revolution is the turning of the Earth around the Sun. One complete cycle around the Sun is one year. Just remember this little saying and you'll be good! The Earth's tilt: the very thing we need to make seasons. Without it, there wouldn't be four seasons, only one. Thanks to: http://www.erinspace.net/
https://www.khanacademy.org/science/cosmology-and-astronomy/earth-history-topic/earth-title-topic/v/how-earth-s-tilt-causes-seasons The axis is always tilted in the same direction, so different parts of the Earth's surface is facing the Sun as it revolves. The Northern Hemisphere When it is directly tilted towards the Sun, it's Summer! When its facing away from the Sun, it's Winter. During the Summer, the North Pole is in constant daylight! During the Winter, the North Pole is completely dark. Comes from the Latin word "aequus" meaning equal Latin for "night" Solstice Means "Sun" Comes from sistere meaning "to stand still" Spring Equinox
March 21-22 Fall Equinox
September 22-23 Summer Solstice
June 21-22 Winter Solstice
December 21-22 The Southern Hemisphere When the Northern Hemisphere is Summer, the Southern Hemisphere is Winter. The Hemispheres are always opposite. When it is tilted directly towards the Sun, its Summer! When its tilted away from the Sun, its Winter! During the Summer, the South Pole is in constant daylight. In the Winter, it's in total darkness. Indirect Sunlight- It strikes over a large surface area and is spread out. This happens during the Winter months. Shortest day of the year Longest day of the year Comes from "sistere" meaning "to stand still"