Does the Sun spin?
Galileo Galilei, back in 1612, noticed something interesting about the Sun when he observed its sunspots. Let's see what he discovered.
Data | Compute Rotation | Your & Galileo's Discovery | Other Pages
Collect Your Data
If you haven't already done so,
collect solar data
for a couple weeks by looking at images from the SOHO spacecraft.
Arrange your copies or drawings of the solar disk
and sunspots in order from longest-ago to the present, and flip through
them slowly as if they were an animated "flip-book".
Are the sunspots permanent, or do they come and go?
Do they stay in the same place, or seem to move? If they move, do they move
in relatively straight lines or do they wander?
Galileo noticed that the spots seemed to move directly across the disk of the Sun. He thought that, if they were on the surface of the Sun, their movement might indicate that the Sun was rotating. What do you think?
Compute the Sun's Rotation Rate
Let's try to calculate the rotation rate of the Sun:
By Calculating the Spots' Angular Velocity
What Did you Discover?
Would you like to compare your sunspot sketches with those made by Galileo?
Did Galileo's sunspots move horizontally across the solar disk? Do your sunspots move horizontally across the solar disk? If your pictures differ from Galileo's, why do you think that is?
This page is https://solar-center.stanford.edu/spin-sun/spin-sun.html
Created by Deborah Scherrer