Hydrogen-Alpha Filters

The chromosphere is a relatively thin layer of the solar atmosphere, nearly 2000–3000 km thick, which lies just above the photosphere and extends into the lower regions of the corona. Due to the temperature rise and lower gas density in the chromosphere, spectral lines are emitted. Hydrogen-alpha (H-alpha or Hα) is the dominant emission line in the chromosphere and can be viewed as a reddish color when isolated using specialized narrowband filters tuned to the 656.3 nm wavelength.