Astronomy 1010-HFall_2015

Day-9Planetary Astronomy

Course Announcements• Read Chapter 2• How is the lunar observing going?• How is the sunset/sunrise observing going?• 1st Quarter night – Mon. 9/21 -7:30pm – on campus• Exam 1: Fri. Sept. 18 or Mon. Sept. 21• This Week: APSU-OUR: Research & Creative Activity

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

Spacecraft Reports• Chantal H. – New Horizons• Ashley G. – Dawn• Mahalia S. – NuStar• Tristan C. – Mangalyaan• Spencer B. – Voyager• Arielle P. – Curiosity Rover• Lars A. – Cassini• Sarah E. – Rosetta• John M. – Mars Phoenix• Jordan T. – Galileo• Rashun B. – Apollo Missions

Definitions & Terms -1• Season: A time

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

Earth’s Axis

Earth’s axis is not perpendicular to the ecliptic plane.

Instead, it is at an angle of 23.5 degrees. This is why there are seasons.

Earth’s Axis

The angle of sunlight is closer to perpendicular in summer.

Energy is more concentrated. The southern hemisphere is opposite the

northern hemisphere.

Special Days of the Year

Summer solstice: Sun farthest north.

Autumnal equinox: Sun on the equator, moving southward.

Winter solstice: Sun farthest south.

Vernal equinox: Sun on the equator, moving northward.

Lecture – TutorialPath of the Sun: pg 89

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

each other.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 one of us for help.

Lecture – TutorialSeasons: pg. 93

Work with a partner!Yada Yada Yada …This one is homework

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

Precession

Currently, the north celestial pole is near the bright star Polaris.

Earth’s axis wobbles with a period of 26,000 years.

Location of the poles slowly shifts.

Earth wobbles like a top, slowly. Since the axis shifts, the equator shifts. Positions of the equinoxes precess as well.

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

The Moon’s Motions

Because the orbit is elliptical and not circular, the rotation speed doesn’t always match the orbital speed.

Full Moon to Full Moon takes 29.53 days

The moon takes the same amount of time to complete one rotation as it does to complete one orbit

Cycle of phases:The synodic month 29.53 days

The Orbital Period is the Sidereal Month: 27.32 days

Lecture – TutorialCause of Moon Phases: pg 81

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 one of us for help.

Lecture – TutorialPredicting Moon Phases: pg 85

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 one of us for help.

Course Announcements• Smartworks Chapter 2: Fri. 9/19

• Read Chapter 2, 3

• Dark Night Observing – • Tues. 9/16 & Wed. 9/24 – 7:30pm at the

Observatory

• Exam-1 – Friday Sept. 19• Bring L-T book to the Exam on Friday

Lecture – TutorialPredicting Moon Phases: pg 85

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 one of us for help.

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

Three types of solar eclipses:• Total: The Moon

completely blocks the Sun’s light.

• Partial: Only part is blocked.

• Annular: The Sun appears as a bright ring surrounding the Moon.

Solar Eclipses

Solar eclipses happen at new Moon. Moon passes between Earth and the Sun. Only a small portion of Earth can witness

each one.

The part of the Moon’s shadow you are in determines which type of solar eclipse you see.

Umbra: Total or annular. Penumbra: Partial.

Lunar eclipses happen at full Moon. Earth is between the Sun and the

Moon. Visible over a wider area of Earth. Last a lot longer than solar eclipses.

Eclipses do not occur every month because the Moon’s orbit is tilted 5.2° with respect to Earth’s orbit around the Sun.

Intersection: line of nodes.

Next one is April 15, 2014 for

North America

The Saros Cycle…18 years 11.3 days

What Would You See on Mars?

Projected Eclipse Times Eclipse Path Point of Greatest Eclipse

Lat.: 36.9664° NLong.: 87.6639° W Total Solar Eclipse Duration of Totality: 2m40.1s

APSU Observatory Lat.: 36.5631° N

Long.: 87.3433° W Total Solar EclipseDuration of Totality: 2m23.4s

Projected Eclipse Times APSU Observatory

Lat.: 36.5631° NLong.: 87.3433° W Total Solar EclipseDuration of Totality: 2m23.4sMagnitude: 1.008

Event Date Time (UT) Alt Azi (C1) : 2017/08/21 16:56:59.80 62.3° 149.7° (C2) : 2017/08/21 18:25:28.70 64.2° 198.9°

Max : 2017/08/21 18:26:40.50 64.1° 199.5° (C3) : 2017/08/21 18:27:52.10 64° 200.2° (C4) : 2017/08/21 19:52:25.50 53.4° 235.2°

Projected Eclipse Weather

Clarksville, TN

Two-Minute Essay My name is…

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