An Orbit System

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A. The Sun: Earth’s Star

1) Star

(a) Huge sphere of glowing hot gases

(b) Medium size

(c) Rotation – 4 weeks

2) Parts of the sun

(a) Photosphere

(1) Bright, visible surface of the sun

(i) Granules

1. Small light and dark areas

2. Movement of gases

3. Dark – cooler

(ii) Sunspots

1. Large dark cooler regions

2. Number varies from 11 – 13 years

(b) Chromosphere

(1) Thin, red layer above photosphere

(c) Corona

(1) Outermost layer

(d) Prominences

(1) Stream of gas shooting up from the sun

(e) Solar flares

(1) Sudden eruptions of gases that travel far into space

(f) Solar wind

(1) Constant streaming of particles from the sun into space

3) Sun’s interior

(a) Core

(1) Gas

(i) Held in sphere by gravity

(2) 15 million ºC

(3) Nuclear fusion

(i) Joining of hydrogen atoms

1. Forms helium

B. Day and Night on Planet Earth

1) Rotation

(a) Axis

(1) Imaginary line through poles of earth

(b) Proof

(1) Pendulum swing

(2) Missile path

(3) Space

(c) Time

(1) Position of the sun in sky

(2) Time zones

(i) A longitude belt, 15º wide

2) Night lights

(a) Aurora

(1) Matter and energy from sun interact with atmospheric gases

(2) Occur mainly at poles

(i) Magnetic field

1. Region around a magnet where a magnetic force is felt

(3) Magnetosphere

(i) Area of space affected by the Earth's magnetic field

(ii) Van Allen Belts

1. Discovered January 31, 1958 by Explorer I

2. James Van Allen

C. Earth’s Orbit and Seasons

1) Revolution

(a) Time it takes to complete one orbit around the sun

(b) Proof

(1) Parallax

(i) Shift in an objects position when viewed from two locations

2) Seasons

(a) Tilt of axis

(1) 23 ½º

(b) Summer

(1) Summer solstice

(i) June 21/22

(ii) Sun’s path highest in sky

(iii) Longest day

(c) Fall

(1) Equinox

(i) September 22/23

(ii) Equal hours of day and night

(d) Winter

(1) Winter solstice

(i) December 21/22

(ii) Sun’s path lowest in sky

(iii) Shortest day

(e) Spring

(1) Equinox

(i) March 20/21

(ii) Equal hours of day and night

3) Time adjustments

(a) Leap year

(b) Daylight savings time

(1) Not nation-wide

D) The Moon: Earth’s Satellite

1) Nearest neighbor

(a) Mare

(1) Galileo called them “seas”

(2) Dark, wide flatlands

(b) Rays

(1) Trails of rock and dust extending from craters

(c) Mountains and ridges

(d) Highlands

           (1) White areas

2) Phases

(a) Changes in the moon’s shape

(b) New moon

(1) Moon between sun and earth

(2) No light

(c) Crescent moon

(1) Thin sliver of moon has light

(d) Quarter moon

(1) One half of the moon has light

(e) Gibbous moon

(1) Almost totally lit

(f) Full moon

(1) Moon is totally lit

3) Eclipses

(a) Moon is not in same plane as earth

(b) Solar eclipse

(1) Earth passes through Moons shadow

(2) Penumbra

(i) Lighter part of shadow

(ii) Sunlight not totally blocked

(3) Umbra

(i) No sunlight at all

(c) Lunar eclipse

(1) Moon passes through Earth’s shadow

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