For this activity you will need the following software:
The word "Planet" in Greek means a
"wanderer", because all these bodies wander about the stars
in the celestial sphere in a semi-regular pattern. Photography
provides an excellent record of a planet's movement. We have
photographed (with a digital camera) several images of a planet
throughout the months of a previous semester. Current students at
WWC will be expected to participate in on-going photography of planets
in the current semester as they become visible. All these images
have been aligned by the instructor so that the stars appear in the
same position in each image frame.
Here is a brief preview of the activity.
Download the images from one of the sites below (more
choices will be added in future years). Be sure to save the
file to disk - don't open it. Each file is a zipped file of
several images. Choose a local directory to store
the file. Use your hard disk if
using your own computer, or a server directory if you are in a campus
computer lab. Be sure to make a new directory with the
appropriate planet name in which to store these files. It is
important to remember where you download the zipped file. In the WWC computer Labs, the downloaded
zipped files are stored in the users server drive (M:). After
download, the user should move the zipped files to a sub-directory in
his/her server drive using a mnemonic name. One separate
directory for a single planet series.
These are self-extracting zip file or plain zipped
files. Follow the
following instructions carefully, and keep these instructions open in
order to follow them.
Open Windows Explorer on your computer. This is the main file navigation program.
Navigate to the folder where you just saved the zip
file. For best results, be
sure to navigate to the folder before extracting. Do not use the
file in the download manager window. The filename ends
"zipped.exe" or "zipped.zip". If you cannot find the file, you
use Search on your Windows explorer. Search for the name of the
file you downloaded. If that fails, download again, noting
carefully where you saved the file. The file name contains
"zipped" in it.
Double-click on the zipped file. This will unpack
several planetary images. When you unpack them, be sure to place
them in a separate folder with the planet and year as a label. If
you don't make a separate folder, you files will be all jumbled up
between different planets and years.
Launch Irfanview. This is an image viewing and rudimentary image editing program. It is free for downloading for educational and personal use.
Open one of the planet images. Use File - Open on the main menu in Irfanview. In the file open dialog you should navigate to the folder containing the images you recently downloaded and unpacked.
Display the best image as a negative (use the Image - Negative from the main menu of Irfanview). Important. It is easier to track and locate stars in a negative image than the conventional positive image. It also conserves ink and toner when printing. Don't print yet!
Annotate the image in Irfanview. Use the mouse to drag a box on the image in one of the image corners, and insert text (Edit - Insert text into selection). Be sure to choose a suitable font - don't use the symbol font!!. Label the image with its date and your name. If you don't like the annotation or the text box is not large enough, use the "undo" command and do it again!
Print the image from Irfanview (File - Print). Do not print if the image is not annotated! Do not print unless the image is a negative (black stars on white background). Choose landscape someplace in the printer properties to get print that is as large as possible. Only print one image.
Plot the locations of the planet on the negative print. Be sure to use pencil so erasures are possible. Locate the planet on the negative print by noting alignments with other stars, etc. Place a small "+" at the correct location and label each "+" with its respective date.
Label any bright stars with their common names
from consulting your planisphere. This is a good place to take a
Note the direction in the sky that the planet wanders - consult the planisphere. Please use the celestial directions (North, South, East, West), not up, down , left , right. Use the planisphere, orient the constellation on your printed sheet so that it matches the orientation on the planisphere, and mark the principal directions on the printout.
All the planets orbit the sun toward the celestial east. Is the planet's apparent motion in this direction? Explain on the basis of the relative motion of the earth and the other planets.
Explain the physical significance of the observations regarding Kepler's laws (see text).