Astro 100 MW



          Astro 100 MW

             The Solar System

             IUPUI, Spring 2023 (Daytime MW)


                    Brian Woodahl (2022)

                    Brian Woodahl (2021)

                    Brian Woodahl (2019)

                    Brian Woodahl (2007)


                    (Don't Use Canvas to contact me, use email link)

                    Office: LD 156-S, 278-9244

                    Class: ET 202, Monday and Wednesday from 12:00 - 1:15


                    Is the University open/closed today?

Bonus Points Reminder

Last Exam (Exam 3) is Wednesday, April 26th, 12:00 to 1:15

Exam 3 Study Guide

Week 15 Images (Monday Only)

15 Bonus Points Opportunity

Week 14 Images

Quiz 10 (Wednesday, April 12)

Week 13 Images

Quiz 9 (Wednesday, April 5)

Week 12 Images

Week 11 Images

Exam 2 (Monday, March 27)

Exam 2 Study Guide

Quiz 8 (Wednesday, March 22)

Week 10 Images

Quiz 7 (Wednesday, March 8)

Week 9 Images

Quiz 6 (Wednesday, March 1)

Week 8 Images

Quiz 5 (Wednesday, February 22)

Week 7 Images

Week 6 Images

Exam 1 (Monday, February 13)

Exam 1 Study Guide

Quiz 4 (Wednesday, February 8)

Week 5 Images

Quiz 3 (Wednesday, February 1)

Week 4 Images

Quiz 2 (Monday, January 30)

Week 3 Images

Quiz 1 (Wednesday, January 18)

Week 2 Images

End-Of-Semester Bonus Points Reminder

Week 1 Images

Course Information

The Most Commonly Asked Question in Astronomy

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. Links for Textbooks (New and Used)

Excellent Beginner's Telescope for General Astronomy

Imagining the Tenth Dimension

Gravity Simulator

FYI (and Just For Fun)

Department of Physics, IUPUI - Updated on April 20, 2023 at 1:31 PM EDT