Images Server for Astro 100

             The Solar System

             Fall 2025, IU Indianapolis

                    Brian Woodahl (2023)

                    Brian Woodahl (2022)

                    Brian Woodahl (2021)

                    Brian Woodahl (2019)

                    Brian Woodahl (2007)

                    bwoodahl@iu.edu

                    (For Canvas Messages, my replies may be slower. Use direct email link for faster replies.)

                    Office: LD 156-S, 278-9244

                    Class: SL 061 on Tues and Thur 10:30 - 11:45

                    http://woodahl.physics.indianapolis.iu.edu/Astro100/

                    Is the University open/closed today?

No In-Person Class on Thursday, November 6

• Instead, in your free time, watch this: YouTube - Planets Beyond Our Solar System by Brian Woodahl

Exam 2 Bonus: +10 Percentage Points Added to Your Exam

• In no less than 1000 words, TYPED, submitted as PDF (not Word or txt, etc.) to bwoodahl@iu.edu, explain one of the topics from the Exam 3 Study Guide. The study guide will be posted next week. Include your full name, the due date is Friday Dec 12th at 1:00 PM. Late submittals (even a few minutes after 1 pm) are not accepted under any condition. NOTICE: Your paper will be scanned using Grammarly Instructor Services for both Plagiarism and AI-generated content.

Week 11 Images

• Large Planet Orbits Star 51 Pegasi (Rendition)

• The Sun and Jupiter Orbit a Center-Of-Mass Point

• Sun's Motion About the Solar System's Center-Of-Mass Point

• Doppler Shift Technique for Finding Extrasolar Planet

• Velocity Data Derived from Doppler Shift of Spectra

• Eccentric Orbits Produce Non-symmetric Velocity Plots

• Calculating an Extrasolar Planet's Mass and Orbit

• Discovered in 2010, Probable Earth-like Planet: Gliese 581 G

• Planets of Star Gliese 581

• Current Wiki on Gliese 581 G

• Current Wiki on Extra-Solar Planets

• Current Listings

Exam 2 (Tuesday, November 4)

• About 80 questions, multiple choice, review all your notes and quizzes

• Closed book and closed notes, bring a scientific calculator

• Bring a pencil, please

• ZipGrade sheets will be provided

Exam 2 Study Guide

• Exam 2 Study Guide (PDF)

Quiz 8 (Thursday, October 30)

• 4 questions, multiple choice, review your notes from previous four lectures

Week 10 Images

• Asteroids Move Significantly During Long-Exposure Photos

• Ceres, 1000 km Across is the Largest Asteroid (Dwarf Planet) in the Asteroid Belt (bright spots theory: brine crystallization)

• Smaller Asteroids Have Nonspherical Shapes

• Asteroid Mass Obtained from the Motion of 'Roid-Moon

• The Asteroid Belt

• The Ahnighito Meteorite from Greenland (34 tons), Displayed at New York Museum of Natural History

• Comet Hale-Bopp in 1997

• Nucleus of Comet Vilt-2 Photographed by Spaceprobe Stardust in 2004

• Coma, Plasma Tail and Dust Tail of Comet

• Comet Dynamics

• Comets Come From Oort Cloud and Kuiper Belt (Previous Image)

• Pluto

• Eris

• Pluto and Eris Orbits (Previous Image)

• Comet SL9 Impacting Jupiter in 1994 as seen from Io (Rendition)

• Impact Scars (Hubble Space Telescope)

• KT (K = Cretaceous, T = Tertiary = Paleogene) Boundary has Thin Layer Rich in Earth-Rare Iridium (red arrow)

• Another KT (K Pg) Boundary Layer

• Mass Extinction Events of the Past 540 Million Years

• Large Asteroid Impacting Earth (Rendition)

• The 1908 Tunguska Event: Forest Damage

• Asteroid Impact Rates on Earth

• Gravity Forces of the Jovians May Send Impactors to Earth

Quiz 7 (Thursday, October 23)

• 4 questions, multiple choice, review your notes from the past five lectures (focus on the most recent 3 lectures)

Week 9 Images

• Sizable Moons of the Jovian Planets

• Jupiter's Io: Volcanically Active

• Source of Io's Heat: Elliptical Orbit and Jupiter's Tidal Forces

• Orbital Resonances Produce Slight Elliptical Orbits

• Jupiter's Europa: Covered With Water Ice

• Europa's Composition

• Jupiter's Ganymede: Largest, Icy, and Dual Surfaced

• Jupiter's Callisto: Icy and Heavily Cratered

• Saturn's Titan: Nitrogen and Methane Atmosphere (Photo NOT Color-Corrected)

• Huygen's Spaceprobe Reveals Some of Titan's Surface Features

• MSNBC Article About Titan (Current)

• Saturn's Enceladus (Image 1)

• Saturn's Enceladus (Image 2)

• Saturn's Enceladus (Image 3)

• Saturn's Enceladus (Image 4)

• Saturn's Rings as Seen by Cassini Spacecraft

• Rings Close Up (Rendition)

• Gap Moon Pan Creates Ripples in the Rings of Saturn

• Origin of Rings

• Neptune's Triton: Captured, Geological Activity

• Triton Close Up

No In-Person Class on Thursday, October 16

• Instead, in your free time, watch this: YouTube - The Jovians by Brian Woodahl

• Also, no quiz this week

Exam 1 Bonus: +10 Percentage Points Added to Your Exam

• In no less than 1000 words, TYPED, submitted as PDF (not Word or txt, etc.) to bwoodahl@iu.edu, explain in your own words the "Bethe Weizsacker Cycle". Make sure your paper includes a short discussion where you contrast it with the Proton-Proton Chain of our Sun. Include your full name, the due date is Friday Nov 14th at 1:00 PM. Late submittals (even a few minutes after 1 pm) are not accepted under any condition. NOTICE: Your paper will be scanned using Grammarly Instructor Services for both Plagiarism and AI-generated content.

Week 8 Images

• Sources of Atmospheric Gases

• Mechanisms for Loss of Atmospheric Gases

• Mars' Orbital Ellipticity: Hemispherical Asymmetry in the Seasons

• Water Ice & Trace Amount of Dry Ice in Mars' North Pole Ice Cap During Northern Hemisphere Summer

• Mars' Global Dust Storm

• Venus' Atmosphere

• The Four Jovians

• Nonsphericity of Jovians

• Detailed Interior Structure of Jupiter

• Interior Structure of Jovians

• Jupiter's Three Cloud Levels: Ammonia, Ammonium Hydrosulfide, Water

• Jovian Cloud Types and Elevations

• Methane: Blue Neptune and Uranus

• Jupiter's Clouds: Different Colors and Different Elevations

• Coriolis Effect on Jupiter's Great Red Spot

• Animation of Jupiter's Cloud Bands and Great Red Spot

Quiz 6 (Thursday, October 9)

• 4 questions, multiple choice, review all your notes from the past three lectures

Week 7 Images

• Moon's Lunar Highlands and Lunar Maria

• Mercury's Caloris Basin

• Mercury's Giant Cliffs

• Theories on Mercury's Giant Cliffs

• Mercury Still Shrinking (Tectonically Active)

• Mars' Southern Highlands and Northern Plains

• Past Volcanism on Mars: Olympus Mons

• Mars' Tectonics: Valles Marineris

• Mars' Ancient Water Erosion by Rivers

• Mars' Ancient Water Erosion by Rainfall: Lack of Small Craters

• Evidence for Water Today (Oct 2005) on Mars: High Resolution Picture 1

• Evidence for Water Today (Oct 2005) on Mars: High Resolution Picture 2

• Evidence for Water Today (Oct 2005) on Mars: High Resolution Picture 3

• Evidence for Water Today (Oct 2005) on Mars: High Resolution Picture 4

• Images for Water on Mars (Sep 2015): High Resolution Picture 1

• Images for Water on Mars (Sep 2015): High Resolution Picture 2

• NASA Presser on Mars Flowing Water (Sep 2015)

• More Evidence: Large Sub-surface Water Lake on Mars (Jul 2018): Image

• Latest Data from Curiosity Rover (Sep 2013)

• Snow Evidence Today on Mars

• Cold Brines on Mars May Support Aerobic Life

• Venus' Surface from Magellan Spacecraft Radar Imagining

• Venus' Surface Close-Up from Soviet Union's Venera Lander Using an Optical Imager

• Terrestrial Atmospheres

• Gravity Creates Higher Pressure and Density Near Surface

• Atmospheric Absorption of EM Radiation

• In The Evening

• Atmospheric Scattering of Light: Blue Daytime Skies and Red Dawn

• Greenhouse Effect

• Pink Floyd DSOM: Scattering of Light: Violet and Blue Scatter More (Bending Angle Greater) Than Red and Orange

• Blue Sky and Red Dawn on Earth

• Coriolis Effect

Quiz 5 (Thursday, October 2)

• 4 questions, multiple choice, review your notes from this week's lectures

Week 6 Images

• Galactic Recycling: Stardust = All the Elements Heavier than Hydrogen and Helium (and tiny bit of Lithium)

• Willie Nelson: Stardust (melody, the memory of love's refrain ...)

• Solar Nebula to an Orderly Solar System

• Composition of Solar Nebula

• The Frost Line

• Early Solar System

• Terrestrial Formation

• Planetesimals must avoid being Shattered

• Jovian Formation

• Accretion Process

• Narration of Solar System Formation

• Surfaces of Terrestrials

• Differentiation of Terrestrial Interiors

• Sources of Internal Heat

• Radioactive

• Cooling Mechanisms

• Impact Cratering

• Volcanism

• Tectonics

• Erosion

• Role of Planet's Size, Distance, and Spin

Exam 1 (Thursday, September 25)

• About 70 questions, multiple choice, review all your notes and quizzes

• Closed book and closed notes, bring a scientific calculator

• Bring a #2 (or HB) pencil (failure to use a pencil results in a zero)

• Scantron sheets will be provided

Exam 1 Study Guide

• Exam 1 Study Guide (PDF)

Quiz 4 (Tuesday, September 23)

• 4 questions, multiple choice, review your notes from the last three weeks (this will also help prepare for the exam)

• Know everything about light

• Know about the fundamental particles (and other aspects of matter)

• Understand the distinction between chemical and nuclear reactions

Week 5 Images

• Saturn

• Uranus

• Neptune

• Planetary Data

• Dwarf Planets Pluto and Eris (with other Kuiper Belt Objects)

• Orbit Details of Eris

• The Asteroid Belt

• Kuiper Belt Objects and Oort Cloud Objects

• Jovians Versus Terrestrials

Quiz 3 (Tuesday, September 16)

• 4 questions, multiple choice, review your notes from the past two weeks

• Know all about Newton, his Laws of Motion, and his Law of Gravity

Week 4 Images

• Atoms

• The Fundamental Particles

• Atom Type (Element) Determined by the Number of Protons

• The Periodic Table (PDF)

• Water (H₂O) Molecule

• Photon (wavy line) Being Absorbed by Atom -> Electron (solid blue line) Jumps Up into Higher Orbit

• Atom Emitting a Photon (wavy line) -> Electron (solid blue line) Jumps Down into Lower Orbit

• Spectra of Helium, Sodium, and Neon

• At The Station

• Sound Produced by Stationary Source

• Sound Produced by Moving Source: Doppler Effect

• Doppler Effect on Spectra: Redshifting and Blueshifting

• Solar System: Sun and Planets (Ignore Pluto)

• Orderly Motion

• Sun

• Mercury

• NASA Mercury Mission (Messenger)

• Venus

• Earth

• Mars

• Ghost on Mars?

• NASA Mars Mission (Curiosity)

• Jupiter

• Jupiter's Great Red Spot

Quiz 2 (Tuesday, September 9)

• 4 questions, multiple choice, review your notes from the past four lectures

• Know the history of Foucault, Galileo, Kepler, Brahe, Copernicus

• Know the numbers/info regarding galaxies, and stars in galaxies

• Know the motion of Earth's path around Sun (ecliptic plane, perihelion = closest to the sun, etc.) and the seasons

• Know about the Moon's motion around the Earth and the phases of the Moon

Week 3 Images

• No Moon, No Gravity, No Tide(s)

• Moon's Gravitational Force Stretches (Pancakes) the Earth Thus Creating Two Tides (on Opposite Sides)

• Moon's Tidal Forces are Squashing (Pancaking) the Earth

• Moon is Lifting Itself into a Higher Orbit

• White Light Contains All Colors

• Duality of Light: Light Is Both a Wave and a Particle

• Wavelength and Frequency

• Inverse Relationship Between Wavelength and Frequency

• Electromagnetic (EM) Spectrum

Quiz 1 (Tuesday, September 2)

• 4 questions, multiple choice, review your notes from last week, know:

• The metric prefix names for various powers of ten

• Dividing two numbers and obtaining the "order of magnitude"

• The number of stars in a galaxy and the number of stars in the observable universe

• The speed-of-light in the metric units

Week 2 Images

• Ptolemaic Model

• Retrograde Motion (Updated)

• Nicolaus Copernicus

• Copernican Model

• Tycho Brahe

• Johannes Kepler

• Galileo Galilei

• Galileo's Venus Phases Supports Copernican Model

• Ptolemaic Model has Limited Phases of Venus

• Foucault Pendulum at Fermilab

• Change in Velocity (either speed or direction) is an Acceleration

• Sir Isaac Newton

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

• Acceleration of an Object Due to Earth's Gravity

• Converting Energy from One Type Into Another Type

Week 1 Images

• Number of stars in the Universe?

• The Milky Way Galaxy

• Andromeda Galaxy (M31)

• The Expanding Universe

• The Reason for the Seasons

• Details of Earth in Motion

• The Phases of the Moon

• Synchronous Rotation (figure on right-hand side)

Course Information

• Syllabus (PDF).

• Master Schedule (PDF).

• These documents may change during the semester.  Please check that you have the latest versions.

The TOTAL SOLAR ECLIPSE of 2017 (Monday, August 21st)

• Totality (Marion, Illinois)

• Baily's Beads, Post-Totality (Marion, Illinois)

• Diamond Ring, Post-Totality (Marion, Illinois)

The Most Commonly Asked Question in Intro Astronomy

• Why don't solar eclipses occur every month (i.e, every New Moon) ?

A solar eclipse only occurs if the New Moon is about within half a degree of the ecliptic plane (defined by the orbit path of Earth as it travels around the Sun). The Moon's orbital path, around the Earth, is (unfortunately) inclined by about 5 degrees to the ecliptic. Thus, there are only two opportunities each moonth (punning) when the Moon passes through the ecliptic. These points are called the nodes (ascending, descending). The Moon passing through a node is not sufficient, it must pass through the node during the New Moon lunar phase.

About twice a year, during an approximately 45 day window (based upon the orbital speeds of the Earth and Moon), the New Moon is close enough to a node that a solar eclipse can occur. Further complicating the motion, the Moon's orbital plane precesses relative to the ecliptic. Hence, the nodes precess around the ecliptic, completing one rotation about every 18.6 years. In addition, because the Moon's path around Earth is elliptical, during many solar eclipses the angular diameter of the Moon is not large enough to fully cover the Sun. Only when the New Moon is near a node and near perigee (i.e. closest to the Earth), does totality occur. On average, it takes about 400 years for totality to occur again at the same geographical location.

Amazon.com Links for Textbooks (New and Used)

• The Cosmic Perspective: The Solar System (7th Edition)

• The Cosmic Perspective, Both Volumes (7th Edition)

• Amazon.com Textbook Rentals

Excellent Beginner's Telescope for General Astronomy

• Orion SpaceProbe 130ST Equatorial Reflector

• Other Telescopes Available in the Astro 100/105 Store

• Texts Also Available in the Astro 100/105 Store

FYI (and Just For Fun)

• Mobile Proton Accelerator Pack

• Time-Elapsed Solar Prominence

• Plage Cloud

• Rhubarb Pie

• Prominences, Filaments, Plages

• Wave

• Electromagnetic (EM) Spectrum

• EM Spectrum and relative sizes

• EM Doppler Shift

• White Light is All the Colors

• Photon Absorption and Emission

• Hydrogen Spectra

• Blackbody Spectral Profiles

• Is Newton's Second Law Correct at Small Accelerations?

Department of Physics, IU Indianapolis - Updated on Nov 5, 2025 at 1:02 PM EST