Due: in class on January 31, 2008
1. Go to the website www.fourmilab.ch/cgi-bin/Solar/action?sys=-Sf to find the current positions of the planets. Print and hand in the page.
2. Which planets are above the horizon for an observer in Eugene
around midnight?
Go the website http://www.fourmilab.to/yoursky, and make (and print) the horizon map for an observer in Eugene at midnight. Does you horizon map consistent with your idea of where the planets would be in the sky using the website in 1? _________
3. Roughly, on what date will Mars next be on the Meridian at
midnight (that is, on what date will the Earth catch-up with Mars)?
You might find that the following link shows the positions of the Earth and Mars more clearly, www.fourmilab.ch/cgi-bin/uncgi/Solar/action?sys=-SI. The preceding website shows only the orbits of the inner planets. You can figure when the Earth catches up to Mars by changing the numbers in the row Time ___ Now ___ UTC. This is the first row under the color diagram. (UTC is for all intents and purposes the time in Greenwich, England.) Click on the rhombus next to UTC and then change the date in the box. The format for the time is year/month/day hours:minutes:seconds. After you enter the appropriate date, hit the update button. When you line things up, print the page and then hand in the page.
4. For Mars, what is the time between two successive crossings of the Meridian at midnight? __________ What is this period called? _____________ How is the period related to the sidereal orbital periods of the Earth and Mars?