171 Ophelia is a large, dark Themistian asteroid that was discovered by French astronomer Alphonse Borrelly on 13 January 1877. It was named after Ophelia in Shakespeare's Hamlet. This object is orbiting the Sun at a distance of with an eccentricity of 0.13 and an orbital period of 5.54 years. The orbital plane is inclined at an angle of 2.55ð to the plane of the ecliptic.
This asteroid is a member of the Themis family of asteroids that share similar orbital elements. It probably has a primitive composition, similar to that of the carbonaceous chondrite meteorites. The body spans a diameter of . An analysis of 40 light curves in 2015 suggested it has a convex, elongated shape with one end smaller than the other.
A 1979 study of the Algol-like light curve produced by this asteroid concluded that it was possible to model the brightness variation by assuming a binary system with a circular orbit, a period of 13.146 hours, and an inclination of 15ð to the line of sight from the Earth. Photometric observations of this asteroid at the Leura Observatory in Leura, Australia during 2006 gave a rotation period of 6.6666 ñ 0.0002 hours and a brightness variation of 0.50 ñ 0.02 in magnitude. This is in agreement with previous studies.
Ophelia is also the name of a moon of Uranus.