Are Sunspots Really on the Sun?
This is the old version of this activity. Click
here for the new version.
To do this activity, you first need to
collect solar data.
Galileo's Dilemma |
Your Experiment |
Other Methods |
More About Galileo
When Galileo Galilei discovered sunspots, he had a problem.
Here it was, 1612, and he had just pointed
his new version of the Dutch tool called a "telescope"
towards the heavens. Not only did he discover the moons of Jupiter,
the "seas" and craters on our own Moon, and the phases
of Venus, but he also found what appeared to be dark smudges on
the Sun. How could this be? After all, the Catholic Church taught
that the heavens were perfect. So there could not be imperfections,
or spots, on the Sun.
Galileo's arch-enemy
Christoph Scheiner
claimed the spots must be tiny undiscovered
planets circling the Sun,
which would occasionally pass in front
of its disk. Galileo proved Scheiner wrong. How?
To find out how Galileo proved Scheiner wrong, let's try an experiment.
- First, we're going to graph some of your sunspot data.
Print out a copy of the
Sunspot Speed Graph.
Note that you will need to figure out the distance, in centimeters,
"traveled" by the spot groups. You will graph that along
with the groups' latitude.
- Pick your best sunspot group, the one for which you have the
most data. What you want to find is how far that group appeared
to travel across the Sun's disk.
- To figure out how far the group moved from the first to second
day, subtract your measured distance (the one you measured on
your sketch from the left edge of the Sun) of the first day from
the measured distance of the second day. (e.g. if your Day #1 = 3 cm
and Day #2 = 4.5 cm., the distance would be 4.5-3 = 1.5 cm).
Now, graph that point above the latitude measurement for
the second day.
- Figure out how far the spot group moved between each of the
rest of your days, and place their points on the graph. If you
have a day missing, figure the distance the spot group moved in
2 days and use half that amount for each of the 2 days.
- Once your data is plotted, draw a line/curve between the points.
To minimize recording errors, graph one or two more sunspot
groups just as you did the first.
What did you notice?
Did the spots' movement across the disk
remain constant? If the distances traveled, and hence the speeds,
were different, in what areas of the Sun did they appear faster, slower?
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