Spectroscopy techniques are focused on spectra of molecules of interest to the Earth’s atmosphere and/or astronomy and astrophysics. Laboratory spectroscopy as well as remote satellite sensing are applied. Using the Fourier transform spectrometer aboard the Atmospheric Chemistry Experiment (ACE) satellite to measure the absorption spectra of the Earth’s atmosphere through solar occultation limb observation demonstrates that volcanic eruption plumes can be located and tracked through their SO2 content. The presence of those plumes is corroborated by overlaying infrared atmospheric aerosol extinction observed by the 1 μm imager on the same satellite. Tracking atmospheric aerosol movement with the ACE imager is also shown to provide key insights into the impact of the unique January 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption on Earth’s atmosphere. ACE satellite data analysis has also been used to better understand seasonal fractionation patterns of NO2 and HNO3 in the stratosphere. Rotational analysis of previously recorded laboratory spectra of the TiO molecule is used to generate new line lists and spectroscopic constants for the E3Π−X3Δ and B3Π−X3Δ electron transitions as well as the A3Φ−X3Δ electron transitions of all four minor TiO isotopologues. New laboratory spectra collected using a Fourier transform infrared spectrometer is shown to improve the known infrared cross sections of cyclohexane