Astronomy 1010Fall_2015

Day-7Planetary Astronomy

Course Announcements• Read Chapter 2• How is the lunar observing going?• This week: Dark Night Observing on Thur. 9/10• 1st Quarter night – Mon. 9/21 -7:30pm – on

campus• Exam 1: Fri. Sept. 18 or Mon. Sept. 21

• This weekend: Thurs. - Sat. – Riverfest• This week: National Adopt a pet week• Next Week: APSU-OUR: Research &

Creative Activity Week. Events in the library 2:30-3:30 every day.

Definitions & Terms -1• Cat: An animal that was once revered as a God by the

Egyptians. Cats have not forgotten this.• Orbit: The path of one body (e.g. a planet) around another

(e.g. the Sun in our solar system).• Orbital Period: The time it takes an orbit to occur.

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 Horizon

Concept Quiz

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

Star A

Star B

1

1

3

2

2

4

4

3 Horizon

Stuff in Chapter 2• Coordinates• Position• Daily Motion (spin of Earth on its

axis)• Visibility of the sky• Year Motion (Earth orbits the Sun)• Seasons (tilt of the Earth’s axis)• Precession of the equinoxes• Motion and phases of the Moon• Eclipses

Nightly Motion of the StarsImagine looking toward the North. What do stars appear to do over the course of an evening?

Nightly Motion of the Stars

Looking North: Stars appear to move counter-clockwise around the stationary North Star (Polaris) – we call these circumpolar stars.

Earth’s rotation causes the Sun, Planets, Moon and stars to appear to move when

viewed from Earth

Photo: Dr. Spencer Buckner

Nightly Motion of the Stars

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

Circumpolar Stars

Circumpolar stars seem to move counter-clockwise around the stationary North Star.

These constellations and stars are visible any night of the year in the NORTHERN sky because they never rise or set!

Examples: Ursa Major, Ursa Minor, Draco, Cepheus, and Cassiopeia

Tutorial: Motion – p.3Work with a partnerRead the instructions and questions carefullyDiscuss your answers with each other.Come to a consensus answer you both agree

onIf you get stuck or are not sure of your

answer ask another groupIf you get really stuck or don’t understand

what the Lecture Tutorial is asking ask one of us for help

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 skyB. high in the southern skyC. high in the western skyD. directly overhead

How long did this picture take and WHY do you

think that?

3-minute Essay