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Earth in Space

Explore Earth's ellipsoidal shape, rotations, revolutions, and seasons in space, affecting day-length, energy, and orbits. Learn about the laws of gravity and inertia.

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Earth in Space

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  1. Earth in Space Section 19.1

  2. Earth’s Shape • Considered to be ellipsoid Oblate spheroid • Earth is wider than it is tall • Bulges at equator, flattened at poles

  3. Earth’s motions Rotation – spinning on an axis - causes day and night The earth moves toward the east causing the sun to appear to move to the west

  4. Earth’s Motions 1. sidereal day The time it takes the Earth to rotate once with respect to a reference star. • One 360° Rotation • Time = 23 hr. 56 min. 1-2: Globe rotates 360° - sidereal 1-3: Globe re-points to sun - synodic

  5. Earth’s motions 2. solar (synodic) day = 24 hours The time it takes Earth to rotate once with respect to the sun. (Sun’s Highest point in sky to the next highest point in sky).

  6. Earth’s Motions • Revolution – movement around a fixed point (sun) • The path of the earth’s revolution around the sun is called an orbit

  7. Earth’s Motions - Revolves once every 365.25 days (year) need leap years - elliptical shaped orbit - Jan. 3 - 147 million km from sun - July 4 - 152 million km from sun

  8. Seasons on Earth • Earth’s axis is tilted 23.5o • The area tilted towards sun has longer days and more radiant energy (summer) • The area tilted away from the sun has shorter days and less radiant energy (winter)

  9. Seasons on Earth • http://www.google.com/url?q=http://www.astronomy.org/programs/seasons/&sa=U&ei=ZmKqT_ucDKaN6QHvreHBBA&ved=0CC4QFjAI&usg=AFQjCNGSxsNkGIzK6LUgpd7s0ZgkrOxDZg

  10. Vernal equinox March 20 or 21 Solstice – the sun reaches the greatest distance north or south of the equator Summer solstice June 21 or 22 Longest day Winter solstice Dec 21 or 22 Shortest day Equinox- the sun is directly above the equator. Equal daylight and night time hours all over the world Autumnal equinox Sept 22 or 23

  11. Earth’s Motions • Precession – Earth’s wobble

  12. Earth’s Orbit • Law of universal gravitation: every object in the universe attracts every other object. IsaacNewton

  13. Attracts all objects towards each other.

  14. Depends on two factors: MASS THE DISTANCE The amount of matter (stuff) in an object STRONGER

  15. MASS WEIGHT VS • The amount of matter (stuff) in an object • Does not change • Force ( a push or pull) of gravity on an object. • Changes depending on where you are.

  16. 265 lbs =120 x 1.6 About 45 lbs

  17. Earth’s Orbit • Inertia – the tendency of an object to resist change in motion • Newton’s first law of motion • An object in motion will stay in motion, in straight line, at a constant speed unless acted upon by an outside force • http://www.seasky.org/solar-system/planet-weight-calculator.html

  18. Earth’s Orbit Inertial force Newton concluded that 2 forces (inertia, gravity) combine to keep Earth in orbit around the sun Gravitational force

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