This project to make your own horn radio telescope caught my eye recently. It looks like a fun and challenging project for a STEM teacher to do with their advanced Year 10 – 12 students. ‘…The telescope is made to pick up the 21 cm band to detect neutral hydrogen from the Milky Way. It can map the hydrogen in the galaxy and also measure the rotational speed of the galaxy using Doppler shift. (Text reference)’
Information about the project can be found at the Open Source Radio Telescopes website.
A Youtube video about the project can be found here.
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