172 Baucis is a large main belt asteroid that was discovered by French astronomer Alphonse Borrelly on February 5, 1877. It was named after a fictional character in the Greek legend of Baucis and Philemon. The adjectival form of the name is Baucidian.
This object is orbiting the Sun at a distance of with an eccentricity of 0.11 and an orbital period of 3.67 years. The orbital plane is inclined at an angle of 10ð to the plane of the ecliptic. Based on infrared measurements, it has a diameter of . It is classified as an S-type asteroid based upon its spectrum.
Photometric observations of this asteroid from the southern hemisphere during 2003 gave a light curve that indicated a slow synodic rotation period of 27.417 ñ 0.013 hours and a brightness variation of 0.25 in magnitude.
Polarimetric study of this asteroid reveals anomalous properties that suggests the regolith consists of a mixture of low and high albedo material. This may have been caused by fragmentation of an asteroid substrate with the spectral properties of CO3/CV3 carbonaceous chondrites.