Astronomy 1010-H Planetary Astronomy Fall_2015 Day-5.

Astronomy 1010-HFall_2015

Day-5Planetary Astronomy

Course Announcements• Smartworks Chapter 1: Due Fri. (Sep. 4)• Read Chapter 2.1, 2.2

• Next week: • Dark Night Observing on Tues. 9/8 & Thur. 9/10

• Thurs. 9-3: Meeting; watch for signs.• Thurs. 9-3: “1st Thursday Art Walk”

downtown, 5pm• Sat. 9-5: Football vs Mercer, 4pm; Tailgate at

1pm

Definitions & Terms -1• Math: A useful tool for investigating science and

torturing students.

• Asterism: A pattern of stars that appears to form a familiar object. It may contain stars from more than one constellation, or be a small piece of a single constellation (example – the Big Dipper) .

Science discovers patterns in nature. Mathematics is the language of patterns. Most phenomena work regularly and

predictably.

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, Pyxsis

An Important AssumptionThe cosmological principle: “There is

nothing special about our place in the universe.”

On one level:Our view from the Earth is not special or

unique.Distant objects should be like nearby ones

which we can study in detail.On another level:

Matter and energy obey the same physical laws everywhere.

Colored Card Question:Principles

Which of these is a restatement of the cosmological principle?

A. The universe is the same everywhere. B. The same rules work everywhere in the

universe.C. There are no phenomena remaining to be

discovered.

Mathematics works when used to describe nature and its patterns.

Basic Tools:• Scientific Notation: handling large or small

numbers• Ratios: comparing• Geometry• Algebra: representation• Proportionality: understanding the relationships

between quantities.

MATH TOOLS 1.1

Graphs are used to represent relationships between quantities.

Can be linear or nonlinear.

For linear, the slope is the change of the vertical axis divided by the change of the horizontal axis.

MATH TOOLS 1.2

Scientific Notation4,500,000,000,000,000 = 4.5x1015

0.000000000000000028 = 2.8x10-17

On calculators…look for the “EXP” keyor the “EE” key

centi = 0.01 = 10-2 (c)

milli = 0.001 = 10-3 (m)

micro = 0.000001 = 10-6 ()

nano = 0.000000001 = 10-9 (n)

kilo = 1,000 = 103 (k)

mega = 1,000,000 = 106 (M)

giga = 1,000,000,000 = 109 (G)

tera = 1,000,000,000,000 = 1012 (T)

Use Winter Triangle to find constellations during evenings

Stuff in Chapter 2Coordinates • 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

Coordinates

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

Is the horizon shown a real physical horizon, or an imaginary plane that extends from the observer and Earth out to the stars?

Can the observer shown see an object located below the horizon?

Is there a star that is in an unobservable position?

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.1Work with a partnerRead the instructions and questions carefullyDiscuss your answers with each otherCome 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 as one of us for help

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

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

Two-Minute Essay My name is…

The scientist (living or dead, but real) I would most like to meet is: