During most of their life, stars are mostly composed of hydrogen and generate energy by converting it to helium. Although other elements are present to give individual stars their “fingerprint” the lines of hydrogen and helium are visible in stellar spectra, as in this tube.
The glass tubes are 25cm long with the capillary portion about 10cm long. An electrode is sealed in each end and attached to a metal end cap with a loop for convenient hookup to wire connections. Each spectrum tube includes an activity guide.