Download Showing retrograde motion with Stellarium Word document

Investigating the motion of planets in Stellarium
Introduction
Planets normally travel Eastward with respect to the stars. But sometimes, they 'reverse' direction and
head Westward – this is called retrograde motion and happens when the Earth, in its orbital motion
around the Sun, begins to catch-up to the planet in its orbit. In this activity you will investigate the
retrograde motion of Mars
Method and Results
1. Open Stellarium and set your location to Cardiff and the time/date to January 27th
2010 at 20:00
2. Go to the Sky & Viewing options window and select ‘Show planets’ , ‘Show planet
markers’ and ‘Show planet orbits’
3. Turn the atmosphere off so that you can always see the starry background
4. From the lower menu bar, turn on the Constellation labels and Constellation lines
5. Find Mars
6. Sketch the relative position of the stars in the constellation of Cancer, and Mars in the
space below
Method and Results cont…
7. From the Date/Time menu option, advance the night sky 6 or 7 hours and continue
to follow Mars
8. Again, sketch the relative positions of the stars and Mars in Cancer below
9. Change the time and date to Feb 12th 2010 at 19:00 and find Mars
10. Is Mars in the same place relative to the other stars in Cancer?
11. In which direction has Mars travelled with respect to the stars in Cancer?
12. Move forward by a day each time to March 25th. Which direction is Mars heading
with respect to the stars?
13. Continue moving forward by a day each time, and watching Mars. What do you
notice as you get into April? Which direction is Mars heading now with respect to
the stars?
Conclusion