Astronomy

Galileo to Fraunhofer: From observations to spectroscopy

This project was developed with primary school students (aged 10-11), middle school students (aged 13-14) and several “scientific improvement” groups in secondary schools where the students are 18-years old . The students build a telescope and a spectroscope with which they can observe the spectrum of different lamps and also the solar spectrum. Angela Turricchia will help participants construct a spectroscope.  
 
Material needed:
 

• paper tube: the inner tube of a toilet roll or black cardboard (10cmx10cm)
• 2 squares of black cardboard (8cmx8cm)
• glue
• scissors, black Sellotape
• diffraction grating (2cmx2cm): an old CD-Rom

1. Cut a slit 0.2 cm x 1.5 cm in the centre of one of the cardboard squares
2. Glue this square to one of the basis of the paper roll . Make sure the glue has dried up, then cut the square, just as large as the cylinder base . Not to let light in, seal the round piece of cardboard to the edges by using the Sellotape. Light should pass only through the slit.
3. Cut a 1-cm-square hole in the centre of the second piece of black cardboard.
4. To prepare the diffraction grating you need the CD-Rom. Prepare the grating by peeling off the silvery, coloured film in the upper part of a CD. Be careful not to scratch it, as it is very delicate.
5. Fix the diffraction grating (the little piece of the CD) to cover the squared hole in the piece of cardboard. Seal it to the edges with Sellotape, pay attention not to cover the diffraction grating.
6. Glue this squared piece of cardboard to the paper roll, on the side of the paper roll which is still free.
7. Now your spectroscope is ready.
8. Look through it. Point the slit towards the source of light, with the diffraction grating close to your eye. What can you see?