The Sun's Rotation

Finally, this is something I've been wanting to do for a while.  I took a picture of the sun at about the same time each day for five days.  I wanted to track the movement of sunspots to see the rotation of the sun.  It is faint, but if you stare at it long enough you can see them.



First I showed the picture from each day for a second. Then I labeled the sunspots and showed the five days again. I know it is hard to see and some days are hazier than others.  The second day seems to have the clearest image.  I took the pictures in the morning so east is down and the rotation direction is up in the images.  The solar rotation is supposed to be about 25 days (it is actually a bit shorter to a stationary observer, but appears a bit longer as viewed from Earth because we are orbiting the sun in the same direction as it rotates).  With a 25 day rotation the spots should cover a slightly less than 1/6 of the way around (the difference from the first image to the last in 4 days, 4/25=0.16, 1/6=0.167), which corresponds to 60 degrees. From looking at an image of degree lines on a globe,

it looks about right to me.  1492 started just above «-60» and ended just above the «Equator». 

Also, according to spaceweather.com, on May 27, the day the first picture was taken, sunspot 1492 erupted and sent storm of particles toward the mars curiosity rover that is still in space in route to mars.  I blogged about curiosity before because of all the steps that had to work during its unprecedented landing.