Study Points• Predict the approximate time of day/night you should look for first quarter moon, full moon,

last quarter moon.

• Explain how astronomers think the Moon formed and give evidence.

• What causes a solar eclipse? What causes a lunar eclipse? What phase is the moon for each?

• Explain why the Earth undergoes seasons. Explain why it is hot in the summer. Explain why the Sun appears high in the sky during the summer but low in winter?

• What is included in the area of the sky known as the zodiac? What does the word zodiac mean? How many constellations are in the zodiac according to astronomy?

• What is the ecliptic plane? Where is the Sun in this plane? the Moon? the planets? the stars?

• What is meant by “the Sun is in Leo”? Explain why you only see some of the constellations of the zodiac at a given time.

• What is meant by the Earth’s precession? Is Earth’s precession a long or a short time?

• Explain why Polaris is the North Star? Explain why the stars appear to revolve around the North Star?

• Explain why the Sun is not in the constellation horoscopes say it is in when you are born.

• What distinguishes science from non-science? Give an example.

• Name the five North Circumpolar Constellations. Why are these important to us in MN?

• Define equinox and solstice? Sketch the Sun, Earth, and Earth’s orbit. Draw Earth with the axis tilt and label the location of Earth at the solstices and equinoxes.

Cycles of the Sky: Part 2

• Moon

– Moon Phases, Motions, Formation

– Lunar and Solar Eclipses

• Zodiac, Ecliptic

• Precession

• North Circumpolar Constellations

• Seasons

Moon Phases

Orerry with light

Moon Phases*

Moon Position at Sunset*

Moon Phases Continued*

Moon Position at Sunrise*

Moon rises ~50 minutes later every day

From Last Moon Lecture

Conclusion on Moon’s motion:

• Minute to minute the Sun, Moon, & stars

appear to rise in east and set in west due

to Earth’s spin (rotation).

• Day to day, Moon moves west to east due

to Moon’s orbit (revolution) around Earth. (Also generally true for other planets, due to the planet’s

orbit.)

On Earth the Sun, Moon & stars (generally) rise in the east

and set in the west because of Earth’s rotation (spin).

WESTEAST

Moon Motion in

One Day (~minute to minute)

Moon Motion Day to Day

Day to day from Earth, the Moon moves EAST because of

the Moon’s revolution (orbit) around Earth.

Moon Revolves

~12 deg/dayMoon

Moon’s

Orbit

Earth East

West

Origin of Moon*• Early Earth and Mars-size object collide*

– Mars-size object known as Thea

• Moon formed out of particles orbiting around the

new collided Earth*

• Moon is made up of materials found in Earth’s

crust (outer layer)

• Watch: How the Moon was formed https://www.youtube.com/watch?v=mQAdYWcA7ig (1:56)

• Watch: Evolution of the Moon (after it formed) https://www.youtube.com/watch?v=UIKmSQqp8wY (2:41)

Image: http://www.seti.org/node/1458

Lunar Eclipses – only at Full Moon*

•If the Moon passes

through Earth’s

shadow, we see a

lunar eclipse.*

•Lunar Eclipse – Earth

blocks the sunlight

from the Moon*

• If the entire surface

of the Moon enters

the umbra, the lunar

eclipse is total.

© Cengage Learning 2014 Orerry with light

Total Lunar Eclipse

• A total lunar eclipse can last up to 1 hour and 40

minutes.

• During a total eclipse, the Moon has a faint, red

glow, reflecting sunlight scattered in the Earth’s

atmosphere.

Lunar Eclipse

Dates• 1 – 2 lunar eclipses

per year usually

• Next one in MN:

May 16, 2022

Total Lunar Eclipse visible from Minneapolis

1/20-21/2019, 9:33pm to 12:50amWatch: Great Video of January Lunar Eclipse

https://www.timeanddate.com/eclipse/in/usa/minneapolis?iso=20190121

Size of the Sun & Moon from Earth

• From Earth

the size of

the Moon

and Sun

are about

the same!

The angular diameter of the Moon (~0.5o) is

almost exactly the same as that of the Sun.

This is a pure coincidence. The Moon’s linear

diameter is much smaller than that of the Sun.

Solar Eclipses – only at New Moon*

Due to the equal angular diameters, the Moon can

cover the Sun completely when it passes in front of

the Sun, causing a total solar eclipse.*

Solar Eclipse – Moon blocks Sunlight from Earth*

Orerry

with

light

Solar Eclipses

The Moon’s shadow sweeps

across the Earth, over points

from where we can see a

solar eclipse.

Total Solar Eclipse

During a total solar eclipse, the solar

chromosphere, corona, and

prominences can be seen.

Diamond

Ring Effect

Solar Eclipse Types

1. Total 2. Annular 3. Partial

4. Hybrid (both total and annular)• Types are due to the changing (angular) size of the

Moon and Sun seen from Earth because the orbits are

not perfect circles (they are ellipses). Wikipedia.com

Solar Eclipse Dates

• About 1 per year; max time is ~7 min

• Next Total Solar Eclipse in USA (TX

to ME): April 8, 2024

– 2033 Alaska; 2044 MT & ND

• Last Total Solar Eclipse across USA

– August 21, 2017 (OR to SC)

– Look at Best Pictures: website link

Very Important Warning:Never observe the Sun directly with your bare

eyes, not even during a partial solar eclipse!

Use specially

designed solar

viewing shades,

solar filters, or a

projection

technique.

Constellations

• Imaginary memory aids to describe sky

• 88 total constellations named in Earth’s

celestial sphere (previously 48 from

Ptolemy about 350 BC)

• Other versions around the world –

Japanese, Chinese, Arabic, Hindu, Native

American

Celestial Sphere

Zodiac Constellations

and the Ecliptic

Zodiac means circle of little animals*http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT301/HTML/AT30103.HTM

Constellations of the Zodiac

• Seen throughout the year because of Earth’s revolution

• The zodiac constellations are located along the Sun’s

path on Earth (Ecliptic Plane).*

• Ecliptic Plane – the plane of Earth’s path around the

Sun.*

• The zodiac region includes the Earth’s path around the

Sun, our Moon’s path, & planets’ paths across Earth’s

sky.*

Annual Motion of the Sun

• The Sun is in Sagittarius on January 1 (sign of Sagittarius)

• The Sun is in Aquarius on March 1 (sign of Aquarius)

• The Sun is in Leo on September 1 (sign of Leo)*

• During the days of a given zodiac sign, that constellation isn’t

visible because it is behind the Sun, as viewed from Earth*Orerry with Sagittarius

Two Versions of Zodiac

Constellations

One constellation missing from the traditional zodiac signs.

http://spaceplace.nasa.gov/starfinder2/en/

• 13 Astronomical

Constellations of the

Zodiac (used by

astronomers) and

includes Ophiuchus*

• 12 Astrological

Constellations of the

Zodiac

• All 13 are in the

ecliptic plane;

Babylonians removed

1 to fit the 12 month

calendar

Precession of Earth• Earth’s Precession – slow movement of Earth’s axis because

Earth is spinning* (traces out a circle as it changes)

• The Earth’s North pole currently points to Polaris so we call

Polaris our North Star, but the North Star will change.*

– Earth’s axis of rotation points to the North Star and stars move around

that point as the Earth rotates

• 3000 BC: North star = Thuban (5000 years ago)

– origin of astrology about 1000 BC, different sign dates (3000 years ago)

• 14,000 AD: North star = Vega (12,000 years in the future)

• 26,000 year cycle (long time)*

Parke Kunkle’s

precession

video(watch if you

miss lecture)Precession wheel demo

What Sign Are you?

• Astrology is based on the locations of the constellations from

about 3000 years ago when the constellations were visible at

different times of the year than they are now.*

• Astrology is not a science; it is a belief system – not testable or

repeatable (science hallmarks: natural, testable & simple)*

• Astronomy uses the same names of constellations and uses all

13 constellations in the ecliptic

• You can look up your astrology sign based on the 13 sidereal

constellations and accurate north star here: http://www.livescience.com/4667-astrological-sign.html

• More about this from NASA here: http://spaceplace.nasa.gov/starfinder2/en/

Discuss

• What do you think of astrology signs? Are

they accurate? Or do they take advantage

of human weakness to want to find truth in

something?

North Circumpolar Constellations• Constellations visible year-round (mid-latitudes & north)*

– Minnesota and further north to the North Pole

• Don’t rise or set; Visible all year and all night

• 5 North Circumpolar Constellations: Ursa Major (Big Dipper),

Ursa Minor (Little Dipper), Cassiopeia, Draco, Cepheus*

Globe & Celestial Sphere

http://antwrp.gsfc.nasa.g

ov/apod/ap040911.htmlhttp://www.captureminnesota.com/

Seasons on Earth

Northern summer =

Southern winter

Northern winter =

Southern summer

• Caused by Earth’s tilt which is about 23 degrees

Globe

Seasons• When the northern hemisphere is tilted toward the sun, it

also experiences longer daylight.

– Longer daylight is the cause of higher temperatures in summer*

• The Earth’s tilt causes longer daylight in one hemisphere

– Show longer daylight with globe & Sun is higher in the sky

www.faculty.edfac.usyd.edu.au

• Equinox: equal night and

day*

• Equinox is when the Sun

is crossing Earth’s

equator*

• Solstice: daylight is

longest in each

hemisphere*

• Solstice is when Earth’s

axis is tilted toward the

Sun in one hemisphere*

Fall

Spring

Summer

Winter

Northern Hemisphere

Seasons

Orerry

Explanation with a friend

• Explain why the Earth undergoes seasons. Explain why it is hot in the summer. Explain why the Sun appears high in the sky during the summer but low in winter?

• Write your own explanation with the help of a classmate. Write 2-4 sentences to explain.

• This will help you understand what you learned today.

Planetarium Observation• Planetarium Start Jan. 28; Due May 5 (10 points) Go to a

planetarium show

• Best Option: Como Planetarium Class Field Trip on Tuesday,

Feb. 4. (FREE!) at Como Elementary School– Bus from Minneapolis College at 8:15am from the corner of Spruce

Place & Harmon Place on the south side of Science bldg., by T bldg.

Bus returns by 10:30am.

– Free show at 9am this day only.

– You can drive on your own but you need to be early because the door

will be locked. Address: 780 West Wheelock Parkway, St. Paul, MN

• If you do not go to the Como Planetarium with the class, then

you can go any time on your own at your own cost – you pay.

See the link at the top for options:– Como Planetarium Tuesdays at 7pm usually – see their calendar

– Bell Museum throughout the week

– Jackson Middle School classroom planetarium

– Make a Shoebox Planetarium

You only need to do this once. If you go to Como on Feb. 4, then there is

no need to do any more for this.

• Continue flashcards of STUDY POINTS

• Do D2L Brightspace Quizzes 1 – 2

• Come prepared to Lab this week

• Test 1 in 2 weeks, Tuesday, Feb. 11

– To prepare: study points & 4 D2L Brightspace quizzes

– About 60 multiple choice questions. Bring a pencil.

– Optional: bring calculator (not graphing); some available here

• Observations – Earth-Sun Scale Model Due TODAY 11:59pm Jan. 28

– Sunset – Part 1 Due Feb. 18 (10 pts)Take picture of sunset (~4pm) at a

place you can return for part 2

– Star Gazing (SG) Due May 12 (20 pts) Go star gazing & write report

– Moon Phases Start Jan. 23; Due Mar. 5 (10 pts) Observe 4 phases &

record in table

– NEW: Planetarium (10 pts) See Calendar info about Field Trip on Feb. 4:

Bus from college at 8:15am and returns by 10:30am.

• You can watch Crash Course in Astronomy #3 & #5 to review

• Grades updated weekly (check for mistakes)

Homework