Observing the sun 

     Despite burning your retina, observing the sun does have many values. We did an experiment using only a telescope with the necessary solar protection equipment (a home made solar filter).

The experiment setup: 

     Knowing the dangers of looking directly at the sun, using a telescope to observe it requires some precautions.

Aligning the telecope to the sun if you have an equitorial mount starts the same as night observation. Set up the mount so it points to the north star. This means that tracking objects requires adjusting only one axis. Then point the telecope roughly in the region of the sun. If the shadow that the telescope tube casts appears just as a circle rather than an oval or rectangle, it means it is pointing directly to the sun.

     If using a refractor, it is possible to observe the sun without a sun filter. This is done by getting a white piece of paper and holding it about 30cm away from the eyepiece. An image of the sun will be projected onto the paper. However, if you want to look through the eyepiece or if you are using a Cassegrain or a Reflector (any telescope with a mirror), then a sun filter must be used. A mirror would be damaged if the sun were to be magnified onto it.

     The first observation that can be made is that the sun appears dimmer at the edges. The diagram below explains why:

>Because the sun's brightness varies across its surface, we can already come to the conclusion that it is a gas object rather than solid like Earth.

If you tap the tube of the telecope, then you may be able to identify slightly darker areas of the sun's surface. This is a result of convection currents in the sun's gas structure. 

Depending on when you observe the sun, you may be able to see "sunspots", or dark spots. More information on the phenomena can be found here:

http://en.wikipedia.org/wiki/Sunspot

As well as identifying the structure of the sun, a simple experiment can show the length of a day:

>We measured that it takes approximately 2 minutes for the sun to travel the Field of View of the eyepiece. We know the FoV to be 0.5°. In a full day (from sunrise to sunset and back to sunrise), the sun travels 360°. To make the numbers easier, we can say it takes the sun 4 minutes to travel a full degree. How long does it take to travel 360°? Simply 360° x 4 minutes = 1440 minutes. So a day lasts 1440 minutes or 24 hours.