Astro 100 MW



          Astro 100 MW

             The Solar System

             IUPUI (Daytime MW)


                    Brian Woodahl (2019)

                    Brian Woodahl (2007)


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

                    Office: LD 156-S, 278-9244

                    Class: IT 155, Monday and Wednesday from 12:00 - 1:15


                    Is the University open/closed today?

Exam 3 (Online: Monday, April 27 at 12:00 PM)

Exam 3 Study Guide

Reminder: Exam 3 Date

Week 13 Images (week of April 20 - April 24)

10 Bonus Points Opportunity

Exam 2 Scores

Computing Your Current Grade

Week 12 Images (week of April 13 - April 17)

Week 11 Images (week of April 6 - April 10)

Exam 2 (Online, Monday, April 6)

Exam 2 Study Guide

CANCELLED: Quiz 8 (Monday, March 30)

Week 10 Images (week of March 30 - April 3)

Quiz 7 (Wednesday, March 11)

Week 9 Images

Quiz 6 (Wednesday, March 4)

Week 8 Images (Monday: E-Learning, Wednesday: Lecture and Quiz)

Quiz 5 (Wednesday, February 26)

Exam 1 Scores

Computing Your Current Grade

Week 7 Images

Week 6 Images

Exam 1 (Monday, February 17)

Exam 1 Study Guide

Quiz 4 (Wednesday, February 12)

Week 5 Images

Computing Your Current Grade

Quiz 3 (Wednesday, February 5)

Week 4 Images

Quiz 2 (Wednesday, January 29)

Week 3 Images

Quiz 1 (Wednesday, January 22)

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 23, 2020 at 8:10 AM EDT