This thesis documents the building of a pressure-scanned Fabry-Perot Spectrometer,
equipped with a photomultiplier and pulse-counting electronics, and its deployment at
the Observatorio del Teide at Izaña in Tenerife, at an altitude of 7,700 feet (2567 m), for
the purpose of recording high-resolution spectra of the Zodiacal Light. The aim was to
achieve the first systematic mapping of the MgI absorption line in the Night Sky, as a
function of position in heliocentric coordinates, covering especially the plane of the
ecliptic, for a wide variety of elongations from the Sun. More than 250 scans of both
morning and evening Zodiacal Light were obtained, in two observing periods –
September-October 1971, and April 1972. The scans, as expected, showed profiles
modified by components variously Doppler-shifted with respect to the unshifted shape
seen in daylight. Unexpectedly, MgI emission was also discovered. These observations
covered for the first time a span of elongations from 25º East, through 180º (the
Gegenschein), to 27º West, and recorded average shifts of up to six tenths of an
angstrom, corresponding to a maximum radial velocity relative to the Earth of about 40
km/s. The set of spectra obtained is in this thesis compared with predictions made from
a number of different models of a dust cloud, assuming various distributions of dust
density as a function of position and particle size, and differing assumptions about their
speed and direction. The observations fit predominantly prograde models fairly well,
but show a morning-evening asymmetry, different in the two observing periods.
Models are investigated containing various components, including prograde and
retrograde orbiting dust around the Sun, a drift of interstellar material though the Solar
System, and light from distant emitting matter. The implications for possible
asymmetries of the Zodiacal Cloud are discussed. Other researches on the Zodiacal
Dust Cloud, before, during, and after my observations, are reviewed, including recent
insights into its structure, orientation, and evolution, up to the present day, and my
observations are evaluated in this context. Period of study, 1970-2007