This paper presents a brief history of optical heterodyne detection of incoherent sources followed by a discussion of the current status of the field as well as possible future applications. Attributes of optical heterodyne detection such as high spectral resolution (λ/Δλ > 106), high sensitivity (≈10-19 W/Hz), and preservation of the signal phase will be discussed. Current applications of optical heterodyne detection of incoherent sources include stellar interferometry, solar radiometry, and the measurement of atmospheric absorption of laser radiation. Each of these experiments will be described, particularly the absorption measurements along the earth-space path for HF, DF, and CO2 lasers. Experimental data will be presented to verify the usefulness of these techniques as well as to compare their performance against theoretical predictions. Possible future applications of optical heterodyne detection of incoherent sources will be discussed including remote detection, monitoring, and tracking of atmospheric pollutants on a local or global scale.