Investigating The Sun-Earth-Moon System
Going Further

Sunspots Through Time

Introduction: The Sun is a constant in our lives: day after day, year after year it shines dependably, unchanging. But is it really unchanging? Under the right conditions, ancient Chinese astronomers sometimes saw spots on the Sun, but not always. Centuries later, Galileo also saw sunspots with his crude telescopes and began to count them on a regular schedule, an activity that modern solar observatories still continue. Every clear day, images are taken of the Sun at observatories like the Big Bear Solar Observatory in California, or the Kitt Peak National Observatory in Arizona. These images provide a record you can use to investigate whether the Sun is really constant or not.

Directions: Go to the Big Bear Solar Observatory (BBSO) web site; www.bbso.njit.edu. Click on Images in the menu bar at left, and select Latest. The page that comes up gives you a selection of image available in the BBSO archive. These images show the Sun in different wavelengths but at nearly the same time so they can be compared with each other. Access the archive of daily images by scrolling to the bottom of the page and clicking on FTP Archive. That brings up a page with a folder for each year of observation at BBSO, beginning in 1982. Click on a year folder to reach 12 folders for each month of that year, and click on a month folder to reach the daily image folders. Click on a daily folder to get the archive images for that day. Look for files with "bbso_white_fi" in their names. These are the white light images. Click on these images to download them.

Navigate around the archive and collect one white light image for (about) each six months from the beginning of BBSO observations in late 1982. This will take a little persistence, since white light images were not taken every day due to bad weather or instrument problems.

Your Report:
1) Open your images in an image processing program such as ImageJ ,and make a movie. Watch the movie and look for any changes in the number, size, and location of the sunspots. Do the sunspots change? Are the changes regular or random? If the changes are regular, describe the pattern of change and the period.

2) Write up your observations and make a presentation to your class using your movie to what you have found.

3) For an additional challenge, repeat the process, but this time using Hydrogen Alpha images (names "bbso_halph" in the BBSO archive), Ultraviolet images (http://sohowww.nascom.nasa.gov/data/soho_images_form.html look for images with "171," "195," "284" or "304" in their names) or X-Ray images (the Yohkoh site; http://umbra.nascom.nasa.gov/yohkoh_archive.html 1991 to 2001 only). How do these images compare with the white light images?