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Sky Motions   Diurnal Motion Sky Motions   Diurnal Motion

Sky Motions Diurnal Motion - PowerPoint Presentation

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Sky Motions Diurnal Motion - PPT Presentation

Annual Motion DIURNAL MOTION Daily East West motion of the sky Due to the Earths rotation 15hour 36024 hours 15hour 1 in 4 minutes Stars fall into two groups Circumpolar never rise or set ID: 760044

annual motion sun sky motion annual sky sun horizon day altitude polaris stars meridian star north zenith pole nighttime celestial equator affects

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Presentation Transcript

Slide1

Sky Motions

Diurnal Motion

Annual Motion

Slide2

DIURNAL MOTION

Daily East / West motion of the sky

Due to the Earth’s rotation (15°/hour)

[360°/24 hours = 15°/hour]

[1° in 4 minutes]

Stars fall into two groups

Circumpolar - never rise or set

Equatorial

Slide3

Circumpolar Stars

Slide4

Equatorial Stars

Slide5

View from the North Pole

Slide6

View from the Equator

Slide7

Coordinate System

Slide8

Celestial Meridian

Circle going through north and south points on the horizon and the zenith

Z

Slide9

Celestial Meridian

Objects on the Meridian are at their highest point in the sky (transit)

Astronomical noon is when Sun is on the Meridian.

Does not mean the Sun is directly overhead.

Midnight is when the Sun is on the Meridian below the horizon.

Slide10

Zenith

This

is a measure of how high above the horizon the star or planet is located. A star on the horizon has an altitude of 0

o

while a star directly overhead (this point is called the

z

http://astro.unl.edu/naap/motion2/starpaths.html enith

) has an altitude of 90

o

.

Slide11

What is the altitude of a star that is exactly halfway between the horizon and the zenith?

Slide12

Polaris and Altitude

Polaris “north star”1 degee from NCPAltitude of polaris is always equal to the latitude of the observer.Equator 0º altitude = 0º North pole 90º altitude= 90º akaGrosse pointe 42º altitude = 42º

Zenith

Slide13

South pole

Can you see

polaris

?

Nope!

Slide14

Annual Motion

Slide15

ANNUAL MOTION-Earth’s revolution

Constellations move

westward

during the year.

Due to Earth’s orbital motion around the Sun

Sun appears to moves

eastward

1°/day

Path of the Sun called the ECLIPTIC

Ecliptic inclined 23.5° to Equator

Horizon calendar

Slide16

Horizon Calendar

Slide17

S

N

W

E

Polaris

On the day of an equinox…

On the day of an winter solstice…

On the day of an summer solstice…

The Sky Dome

Sunrises and Sunsets

Slide18

S

N

W

E

Polaris

Vernal or

Autumnal

Equinox

Summer

Solstice

Winter

Solstice

Starting Points for the Sun

Slide19

Sunrise in Athens

Slide20

Stonehenge

Slide21

Earth’s Annual Motion

Leo

Slide22

Celestial Sphere

Celestial Equator

SCP

NCP

Ecliptic

Vernal Equinox

Autumnal Equinox

23.5°

Slide23

Sun’s Motion Tool

Slide24

Inclined Pole causes Seasons

23.5°

Northern Hemisphere Summer

Northern Hemisphere Winter

N

S

Slide25

Sun’s motion along the Ecliptic

Sun’s Motion

Slide26

Annual Motion Affects the Nighttime Sky

Day 1

9:00 PM

Slide27

Annual Motion Affects the Nighttime Sky

Day 2

8:56 PM

Slide28

Annual Motion Affects the Nighttime Sky

Day 3

8:52 PM

Slide29

Annual Motion Affects the Nighttime Sky

One Year Later

9:00 PM

Slide30

“Stars”

Fixed Stars

Modern concept of stars

Form the Constellations

Planets - traveling or wandering stars

Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn

Meteors - “shooting stars”

Comets - “long-haired stars”

Slide31

Babylonian Astronomy

Slide32

Babylonian Astronomy

Star Charts

Slide33

Babylonian Astronomy

Fatalistic Pre-determinism

Everything in nature pre-determined by the gods

Doesn’t lend itself to model building

Infinite time line

Slide34

End of Section