1. Earth as a Planet Earth’s position in space Shape & Size of Earth
Not the center of the Solar System
Elliptical orbit
Plane of the ecliptic
Shape & Size of Earth
Oblate spheroid
Motions of Earth
Revolution
Year
Rotation
Day
Precession
Epoch

2. Earth as a Planet Revolution Our movement around the Sun
Counter-clockwise
93,000,000 mi. away
66,000 mi./hr. (average)
Faster in winter, slower in summer
Kepler’s 2nd Law
days to complete
How do we mark this time?
Sidereal year

3. Earth as a Planet Kepler’s 2nd Law
The orbital speed of a planet varies so that a line joining the Sun and the planet will sweep over equal area in equal time intervals.
1mo.
1 mo.

4. Earth as a Planet Key variables in the causes of seasons
Tilt of the Earth’s axis
23.5 degrees
Location of the Earth in its orbit
Latitudes as it Relates to the Sun
Equator – 0 degrees
Tropic of Cancer – 23.5 degrees N
Tropic of Capricorn – 23.5 degrees S
Arctic Circle – 66.5 degrees N
Antarctic Circle – 66.5 degrees S
An Analemma

5. The Earth as a Planet Seasons 2 solstice
Solstice = “Sun stand still”
June 21 or 22 –Summer Solstice
December 22 or 23 – Winter Solstice

6. The Earth as a Planet Sun’s position in the sky Summer Solstice
Rise - NE
Noon
Set – NW
Length of the day
Winter Solstice
Rise – SE
Set – SW
Length of Day

7. The Earth as a Planet Seasons 2 equinox
Equinox = equal (day & night hrs.)
March 21 – Spring Equinox
September 21 – Fall Equinox
Sun’s position in the sky
Rise – directly east
Noon
Set – directly west
Length of the day

8. Earth as a Planet Rotation Precession
East to west direction (here on Earth)
Also west to east (viewed from space)
23:56:04
15 degrees/hr.
Foucault pendulum
Precession
26,000 yr. cycle
Significance of the North Star

9. The Earth as a Planet A system of coordinates Latitude Longitude
Parallels
Measures N & S
Runs E & W
Equator
Longitude
Meridians (long lines)
Measures E & W
Runs N & S
Prime Meridian
Greenwich, England

10. The Earth as a Planet Latitude & Longitude of Kansas City, MO
Latitude & Longitude of St. Joseph, MO
39 degrees 45 minutes seconds N
94 degrees 47 minutes seconds W
Latitude & Longitude of Kansas City, MO
39 degrees 06 minutes 34 seconds N
94 degrees 35 minutes 18 seconds W

11. Earth as a Planet Measuring Time AM – ante meridian PM – Post meridian
Midnight
Noon
Solar day – 24:00:00
Sidereal day – 23:56:04

12. Earth as a Planet The Moon Rotation & Revolution Phases Synchronous
Same side always faces toward the Earth
Phases
New
Waxing Crescent
Illuminated area is increasing
1st quarter
Waxing Gibbous
Full
Wanning Gibbous
Last quarter
Wanning Crescent

13. Earth as a Planet Eclipses Solar (New Moon) Lunar (Full Moon)
Moon is between Earth & Sun
Umbra
Penumbra
Fig
Lunar (Full Moon)
Earth is between Sun & Moon
Eclipses do not happen every month
Moon’s orbit is inclined 5 degrees