1. Earth’s Movement

2. Rotation Earth rotates on its axis once every 23 hours and 56 minutes.
What is another term we might use for rotating?
spinning
Rotation on its axis causes what?
Day and night

3. How fast are we spinning?
467 m/s counterclockwise when viewed from above the north pole
An animation of earth’s rotation and revolution.
Foucault's Pendulum Explained
Foucault's Pendulum Chicago

4. Earth’s Shape Earth is not a perfect sphere.
Rotation of the planet has slightly flattened it out, so it has a larger diameter at the equator than at the poles.
The equatorial diameter of Earth is 12,756 km, its polar diameter is 12,713 km.

5. Revolution Our revolution around the sun is also called our orbit.
The earth’s orbit is shaped like an ellipse.
We revolve around the sun once every days.
What do we call that period of time?
A year

6. Kepler’s Laws
1st law: each planet orbits the Sun in a shape called an ellipse.

7. 2nd law: An imaginary line sweeps equal amounts of area in equal amounts of time hence planets move fastest when they are closest to the Sun

8. 3rd Law: P (orbital period) squared equals a (semimajor axis of the orbital ellipse) cubed.
Or P2 = a3

9. Mercury’s Orbit/Rotation
Compare Mercury’s orbit to Earth’s
Mercury's Orbit

10. Revolution Continued
The sun is not directly in the center of Earth’s elliptical orbit.
perihelion/aphelion

11. Seasons
The perihelion and aphelion are not responsible for the seasons but rather the tilt of Earth’s axis.

12. Seasons

13. Seasons

15. Summer solstice: the Sun is directly overhead at the Tropic of Cancer.
Winter solstice: the Sun is directly overhead at the Tropic of Capricorn
Equinox: “equal nights”; the axis is not pointed at the Sun
Autumnal – the northern hemisphere is beginning to tilt away from the Sun
Vernal – the northern hemisphere is beginning to tilt toward the Sun

16. Precession The wobble in Earth’s rotational axis.
Currently the axis points toward Polaris – by 14,000 the axis will point toward Vega
In this alignment winter will occur in the northern hemisphere when we are at aphelion so winters will be very cold and summer will occur when we are at perihelion so summers will be very hot.
precession animation

17. Nutation
A small oscillation in the precession of earth’s rotation.

19. Barycenter
The point between two objects where they balance each other.

20. Earth-Moon Barycenter video

21. Earth's Movement video

22. Tides Periodic rise and fall of sea level
Caused by the moon’s and to a lesser extent the sun’s gravitational pull on the earth

23. Spring Tide
the largest tidal ranges – differences in high and low tide
Occur when the moon, sun and earth are aligned or at the full moon or new moon phases

24. Neap tide Lowest tidal range
Occurs when the moon is perpendicular to the earth sun alignment

28. Earth
Solar System
Galaxy
Local Group
Local Supercluster
Universe

30. Formation of our Solar System
Nebula – a cloud of dust and gas
Nebular theory: the sun and planets formed from a rotating disk of dust and gases.
As the speed of rotation increased the disk would flatten and matter became more concentrated in the center which formed the sun
The growth of planets began as solid bits of matter began to clump together

32. The Milky Way

34. Big Bang Theory
Steady State Theory
Inflation Theory

35. The most widely accepted theory for the formation of our universe is the Big Bang Theory first proposed in the 1930s.
Time began billion years ago when all the matter in the universe exploded from a singularity a dense point with a infinitely small volume.
As matter and energy began to move outward gravity caused the matter to condense and form galaxies.

36. The universe appears to be expanding.
The Big Bang predicts that the composition of the universe should be 75% hydrogen and 25% helium which it is.
The Big Bang explosion should have left behind radiation. The Cosmic Background Radiation was first detected in 1965.

37. Proposes that the universe looks the same and has always looked that way
Proposes that new matter is created and added to the universe as it expands

38. proposes a period of extremely rapid (exponential) expansion of the universe prior to the more gradual Big Bang expansion