did you get the key ideas from the seasonal stars lecture tutorial?

Did you get the Key Ideas from the

Seasonal Stars Lecture Tutorial?

Post Tutorial Question

What component of Earth’s motion causes the stars to rise earlier on successive nights?

A) its rotation about its axis

B) its orbit around the Sun

C) the tilt of its rotation axis

Pisces

Aries

Taurus

Gemini

Cancer

Figure 2 – What it would look like if you were the observer in Figure 1

South

North Star

365 days

1 day

Aries

Pisces

Taurus

Gemini

Cancer LeoVirgo

Libra

Scorpius

Sagittarius

Capricornus

Aquarius

Figure 1

E W

W

E

Two months from the time shown

what constellation will be high in the Southern sky, at

Midnight? At Noon?

What sign will a person be if they are born at that

time?

For more practice at this – Look back at Part I of the “Seasonal Stars” Lecture Tutorial

Post Tutorial Question

One night, you see the star Sirius rise at exactly 7:36 PM. The following night it will rise

A) slightly earlier.

B) at the same time.

C) slightly later.

Post Tutorial QuestionOne evening at midnight, you observe Leo high in

the southern sky at midnight. Virgo is to the east of Leo and Cancer is to the west. One month earlier, which of these constellations was high in the southern sky at midnight?

A) Leo

B) Virgo

C) Cancer

How do we define what time it is?

http://www.jgiesen.de/SiderealTimeClock/index.html

What time is it now?

How do we define a day?

Tutorial: Solar vs. Sidereal Day p.11

Work with a partner!Read the instructions and questions carefully.Discuss the concepts and your answers with one 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 me for help.

Which takes longer to complete?A) one solar day.

B) one sidereal day.C) Both take the same amount of time.

Image that Earth begins orbiting the Sun twice as fast while maintaining the same rotation

rate. It now orbits once around the Sun every 6 months. In this case, what happens to the

length of the solar day?

A) It gets slightly longer.B) It does not change.C) It gets slightly shorter.D) It is cut in half.E) It doubles.

The changing position of the Sun during the year!

How can we describe the motion of the sun in the sky?

westsouth

meridian

east

Zenith or overheadX

How can we describe the motion of the sun in the sky?

east westsouth

zenithmeridian

PM or post meridian

AM or ante meridian

LUNCH!!

Where is the Sun at noon today?

east westsouth

zenith

here or there?

east westsouth

zenith

there

What about tomorrow at noon?

Where is the Sun at noon today?

What about the path of the Sun?

east westsouth

zenith

there

What about tomorrow at noon?

JUST A LITTLE LOWER !!

Where is the Sun throughout the year?

east westsouth

zenith

Dec 21 Winter Solstice

June 21 Summer Solstice

Mar 21 (Vernal) and Sept 21 (Autumnal)

Equinox

east westsouth

zenith ONE YEAR

The time for the sun to go from

being highest in the sky at noon, to

lowest and back to highest

again is…

Where would the Sun be on your birthday?

Rising

Setting

Hour by hour of path of sunfrom the southern hemisphere!

Position of the Sun when photographed during the day of the winter and summer solstice

Shadow Paths

Sundial Time Lapse

Path of the Sun when photographed from Phoenix, the Mars rover, up near

the north pole of Mars.

Sun at the exact same timeof the day over the course ofa full year.

The shape is called an analemma.

This picture shows every 10 days.

Altitude of the Sun Animation• Note where the sun rises and sets • Note how the altitude of the sun changes during a

day and over the course of the year. • Note how the shadow changes during a day and

over the course of the year.

http://astro.unl.edu/naap/motion3/animations/sunmotions.swf

Tutorial: Path of the Sun p.87




Tutorial: Seasons p.91

0/0

Under which of the following circumstances will a vertical flagpole not cast a shadow as seen from

the continental United States?

A. every day at noon

B. every day at the time when the sun is highest in the sky

C. when the sun is highest in the sky on the summer solstice

D. when the sun is highest in the sky on the winter solstice

E. none of the above

If you are located in the continental U.S. on the first day of October, how will the position of the Sun at

noon be different two weeks later?

A. It will have moved toward the north.B. It will have moved to a position higher in the sky.C. It will stay in the same position.D. It will have moved to a position closer to the horizon.E. It will have moved toward the west.

For an observer in the continental U.S., which, if any, of the x’s (a – e) in the figure below

correctly shows the position of the Sun’s shadow at noon? Choose all that could be correct.

Note that the position of the Sun’s shadow at noon on the Winter and Summer Solstices are

shown.

For an observer in the continental U.S., which of the three shadow plots, shown at right, correctly depicts the Sun’s motion

for one day?

A. Shadow plot AB. Shadow plot BC. Shadow plot CD. More than one of the plots are possible, on different days of the

year.E. None of the plots are possible.

xx

xxxx xxxx

xx

xx xx

xxxx

xx

xxxx

xx

NORTH

SOUTH

WEST

Shadowplot A

Shadowplot C

xx

xx

xx xx xx xx xxxx

Shadowplot B

EAST

Time?What causes Seasons?

Angular Momentum• If something is

spinning, the axis of rotation resists a change in direction.

Precession

26,000 years

Time?What causes Seasons?

Rising

Setting

Hour by hour of path of sunfrom the southern hemisphere!

When the Sun is high in the sky during the day, the number of daylight hours is greater and the amount of direct sunlight

received is greater. This results in Summer.

When the Sun is low in the sky during the day, the number of daylight hours is less and the amount of direct sunlight

received is less. This results in Winter.

The tilt of Earth’s axis of rotation produces longer (or

shorter) hours of more (or less) direct sunlight

1

23

4

Which positions (1, 2, 3, or 4) correspond with which seasons (fall, summer, spring, winter) for the northern hemisphere?

What about the southern hemisphere?

The tilt of Earth’s axis of rotation produces longer (or shorter) hours of more (or less) direct sunlight

Looking at the images below, which letter (a-e) best represents winter in the United States?

Sunlight Sunlight

Sun

a

b

2

3

c

e

Note: this drawing is not to scale. In fact you could fit more than 11,000 Earths between the Sun and the Earth.

d

1

23

4

What are the possible dates for positions 1, 2, 3, and 4?

The tilt of Earth’s axis of rotation produces longer (or shorter) hours of more (or less)

direct sunlight

Time?Seasons on Mars?

Tutorial: Seasons p.91




Which of the locations identified with an “x” for each of the situations (A – E) would experience the coolest temperature

over the course of one day?

Which of the following describes one reason that the Northern and the Southern Hemispheres have different seasons at the same time?

a. The Earth is closer to the Sun during summer in the Southern Hemisphere and is farther from the Sun during winter in the Northern Hemisphere.

b. During a day of the year when the Sun is high in the sky in the Northern Hemisphere it will be low in the sky in the Southern Hemisphere.

c. Earth is tilted, so the Sun is closer to one hemisphere than the other, which causes one hemisphere to be in winter and the other in summer.

d. The energy received at Earth from the Sun changes throughout the year providing more energy to one hemisphere than the other.

e. None of the above.

Which of the following locations experiences the smallest amount of change in sunlight overthe course of a year? a. north pole b. south pole c. equator d. They all experience the same amount of change in sunlight over a year.

Which of the following locations experiences the smallest amount of change in sunlight over the course of a year?

a. north pole b. south pole c. equator d. They all experience the same amount of change in sunlight over a year.

If Earth were tilted more (60o rather than 23.5o), then during winter at your location you would: a. experience cooler temperatures. b. experience warmer temperatures. c. not experience any significant change in temperature.

GO CONFIDENTLY IN THE DIRECTION OF YOUR DREAMS!! LIVE THE LIFE YOU’VE IMAGINED

did you get the key ideas from the seasonal stars lecture tutorial?

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