Refractor and Reflector

Lens Mirror

RECAP

The Celestial Sphere

&

more on

Constellations

(Week 4)

34 deg.

90 deg.

Latitude

Rotation

Daily Changes Revolution

Monthly Changes

Why do we see what we see??

The Zodiac

Constellations – the 88 semi-rectangular regions that make up the sky

• Northern constellations have Latinized

Greek-mythology names:

– Orion, Cygnus, Leo, Ursa Major, Canis Major,

Canis Minor

• Southern constellations have Latin

names:

– Telescopium, Sextans, Pyxis

What do you think?

• What causes the stars to move?

• Do the stars actually move in the way they

appear from Earth?

• Do the stars stay in the same position in the

sky all day/night long?

Consider the dome of the sky over our heads….

mixing bowl

inverted mixing bowl ….

Consider the dome of the sky over our heads….

Imagining a spinning

Celestial Sphere

surrounding Earth

aids in thinking

about the position

and motion of the

sky

Animation of Celestial Sphere

http://bcs.whfreeman.com/universe6e/pages/bcs-

main.asp?v=category&s=00110&n=01000&i=02110.02&o

=|02000|01000|&ns=0

Imagining a spinning Celestial

Sphere surrounding Earth aids in

thinking about the position and

motion of the sky

Altitude is like

latitude or

declination

Celestial Sphere Rotation

Celestial Sphere

Rotation

North Star

Star A

Star B

1

1

3

3

2

2

4

4

Earth’s Equator

Figure 1

Celestial Sphere

Celestial Sphere Rotation

Celestial Sphere

Rotation

Celestial Sphere

Star A

Star B

1

1

3

2

2

4

4

3

Figure 2

Horizon

1) Explain how to find North on the horizon from the North star.

2) Where is the North star when you’re at the North pole?

Celestial Sphere

Celestial Sphere Rotation

Celestial Sphere

Rotation

Celestial Sphere

Star A

Star B

1

1

3

2

2

4

4

3

Figure 2

Horizon

1) Is the horizon shown a real

physical horizon, or an

imaginary plane that extends

from the observer and Earth

out to the stars?

2) Can the observer shown

see an object located below

the horizon?

3) Is there a star that is in an

unobservable position?

4)When a star travels from

being below the observer’s

horizon to being above the

observer’s horizon, is that star

rising or setting?

Tutorial: Position – p.1

PUT NAMES in Tutorials• Work with a partner

• Read the instructions and questions carefully

• Talk to each other and discuss your answers with each another

• Come to a consensus answer you both agree on

• If you get stuck or are not sure of your answer ask another group

• If you get really stuck or don’t understand what the Lecture Tutorial is asking ask your Professor for help

• I WILL BEGIN STAMPING TUTORIALS A LITTLE BEFORE YOU FINISH THE TUTORIAL SINCE THERE ARE 70+ OF YOU, BUT YOU MUST ALL FINISH THE TUTORIAL OR YOU WILL GET A ZERO! DO NOT WALK OUT OF THE ROOM OR GET OFF TASK WHEN WE ARE COMPLETING A TUTORIAL OR YOU WILL GET POINTS DEDUCTED OR GET A ZERO!

• IF THE TUTORIAL IS COMPLETED AT THE END OF LECTURE, NO ONE IS ALLOWED TO LEAVE EARLY UNLESS YOU CHECK WITH ME FIRST! IF YOU LEAVE EARLY YOU’LL GET A ZERO.

Did you get the Key Ideas from the Position

Lecture Tutorial?

In what

direction is the

observer

facing?

A. toward the South

B. toward the North

C. toward the East

D. toward the West

Celestial Sphere

Celestial Sphere Rotation

Celestial Sphere

Rotation

Celestial Sphere

Star A

Star B

1

1

3

2

2

4

4

3

Figure 2

Horizon

Imagine that from your current location you

observe a star rising directly in the east.

When this star reaches its highest position

above the horizon, where will it be?

A. high in the northern sky

B. high in the southern sky

C. high in the western sky

D. directly overheadCelestial Sphere

Celestial Sphere Rotation

Celestial Sphere

Rotation

Celestial Sphere

Star A

Star B

1

1

3

2

2

4

4

3

Figure 2

Horizon

Where would

the observer

look to see the

star indicated by

the arrow?

A. High in the Northeast

B. High in the Southeast

C. High in the Northwest

D. High in the Southwest

Celestial Sphere

Celestial Sphere Rotation

Celestial Sphere

Rotation

Celestial Sphere

Star A

Star B

1

1

3

2

2

4

4

3

Figure 2

Horizon

Telescope Field of View

Field of View = Eyepiece apparent FOV ÷ Magnification

Large Magnification = Small field of view

Small Magnification = Large Field of view

Moon=0.5 deg.

Right Ascension (RA) and

Declination (Dec) are similar

to latitude and longitude on

the surface of the Earth.

Latitude and longitude are

fixed with respect to positions

on Earth. But RA and Dec

are fixed with respect to

positions of stars in the sky.

What is moving, the celestial

sphere or the Earth?

To an Earthling observer,

what appears to move?

Declination (like latitude) is measured in degrees north or south of the Celestial

equator.

Right ascension (like longitude) is measured in units of hours, minutes, and seconds

eastward from the position of the vernal equinox on the Celestial equator. The Vernal

Equinox is the position of the Sun on the first day of Spring.