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Earth in Space

Earth in Space. Chapter 19 Section 1 Pages 659-664. Astronomy. The Study of the moon, stars and other objects in space. Ancient Egyptians were among the first to study the stars. Ancient Astronomers studied the movements of the sun and moon as they appeared to travel across the sky.

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Earth in Space

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  1. Earth in Space Chapter 19 Section 1 Pages 659-664

  2. Astronomy • The Study of the moon, stars and other objects in space. • Ancient Egyptians were among the first to study the stars. • Ancient Astronomers studied the movements of the sun and moon as they appeared to travel across the sky.

  3. Rotation • Earth’s rotation (spinning) on its axis. • Axis- Imaginary line that passes through Earth’s Center and the North and South Poles. • Rotates at 1,600km/h • Causes Day and Night • Takes 24 hours for one rotation.

  4. Revolution • The movement of an object around another object. • One complete revolution around the sun is called a year. (365.25 days) • Earth revolves around the sun in an orbit.

  5. Calendars • Ancient Egyptians- one of the first calendars. Had 12 months of 30 days, with an extra 5 days not apart of any month. • Early people used moon cycles as a calendar. • 29.5 days • Called “Moonths” month.

  6. Calendars • 365.25 creates the need for a leap year. • The Romans adopted this calendar. • 11 months of 30 or 31 days. • February having 28 or 29 days.

  7. How Sunlight hits Earth • Sunlight hits the Equator directly. • Closer to the poles, sunlight hits the surface at an angle. • The energy is spread out.

  8. Earth’s Tilted Axis • Earth has seasons because its axis is tilted as it revolves around the sun. • Tilted 23.5˚ • Earth’s seasons are not affected by changes in Earth’s distance from the sun. • Furthest on July 4th • Closest on January 4th

  9. Reasons for Seasons Chapter 19 Section 1 Pages 659-664

  10. Summer Solstice • The sun’s most direct rays reach the hemisphere that is tilted more towards the sun. This day is known as the summer solstice. • The most direct rays • are directly over 23.5˚N (Tropic of Cancer) for the Northern hemisphere on June 20 or 21 • 23.5˚S (Tropic of Capricorn) for the Southern hemisphere on December 20 or 21.

  11. Summer Solstice • The hours of sunlight are the greatest • The Sun is highest in the sky at noon. • At this time, the northern hemisphere is pointing toward the Sun. (Position A). • The Southern hemisphere is pointed towards the Sun. (Position C)

  12. Winter Solstice • The northern or southern hemisphere is pointed away from the sun’s most direct rays. Known as the winter solstice. • The hemisphere pointed away from the sun receives less direct rays. • These rays are directly over • 23.5˚S (Tropic of Cancer) for the Southern hemisphere on June 20 or 21 • 23.5˚N (Tropic of Capricorn) for the Northern hemisphere on December 20 or 21

  13. Winter Solstice • The hours of daylight get shorter and the Sun is lower in the sky at noon. • At this time, the northern hemisphere is pointing away the Sun. (Position C) • TheSouthern hemisphere is pointed toward the Sun. (Position A)

  14. Equinoxes • The Sun’s most direct rays are directly over the Earth’s equator. • There is an equal amount of day and night (12 hours of day, 12 hours of night) every where on Earth. • Equinox means equal night.

  15. Equinoxes • There are two equinoxes a year, • Autumnal Equinox (fall) - September 22 or 23 (Position B) • VernalEquinox (spring) March 22 or 23 (Position D)

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