Astro 100

             The Solar System

             IUPUI (Daytime)


                    Brian Woodahl


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

                    Office: LD 156-S, 278-9244

                    Class: LE 101, Tu,Th 10:30 - 11:45


                    Is the University open/closed today?

Quiz 8 (Tuesday, October 24)

Week 10 Images

Week 9 Images

Quiz 7 (Thursday, October 12)

Week 8 Images

Quiz 6 (Thursday, October 5)

Week 7 Images

Quiz 5 (Thursday, September 28)

Week 6 Images

Exam 1 Scores

Exam 1 (Thursday, September 21)

Exam 1 Study Guide

Quiz 4 (Tuesday, September 19)

Week 5 Images

Quiz 3 (Tuesday, September 12)

Week 4 Images

Quiz 2 (Tuesday, September 5)

Week 3 Images

Quiz 1 (Tuesday, August 29)

Week 2 Images

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

The Most Commonly Asked Question in Intro 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.

Week 1 Images Links for Textbooks (New and Used)

Excellent Beginner's Telescope for General Astronomy

Course Information (Available August 23rd, but possibly sooner)

Imagining the Tenth Dimension

Gravity Simulator

FYI (and Just For Fun)

Department of Physics, IUPUI - Updated on October 19, 2017 at 9:01 AM EDT