| Minorplanet: | yes |
| 4031 Mueller | |
| Background: |
|
| Discovery Ref: |   |
| Discovered: | 12 February 1985 |
| Mpc Name: | (4031) Mueller |
| Alt Names: | 1985 CL |
| Named After: | Jean Mueller |
| Mp Category: | main-beltHungaria  |
| Orbit Ref: |   |
| Epoch: | 4 September 2017 (JD 2458000.5) |
| Uncertainty: | 0 |
| Observation Arc: | 32.13 yr (11,734 days) |
| Perihelion: | 1.7394 AU |
| Semimajor: | 1.9342 AU |
| Eccentricity: | 0.1007 |
| Period: | 2.69 yr (983 days) |
| Mean Motion: | / day |
| Inclination: | 18.909° |
| Asc Node: | 355.88° |
| Arg Peri: | 69.444° |
| Dimensions: | km 5.56 km |
| Rotation: | h h h h |
| Albedo: | 0.30 |
| Spectral Type: | E X  |
| Abs Magnitude: | 13.213.7 |
4031 Mueller, provisional designation, is a Hungaria asteroid from the inner regions of the asteroid belt, approximately 4 kilometers in diameter. It was discovered on 12 February 1985, by American astronomer Carolyn Shoemaker at Palomar Observatory, California, and named after astronomer Jean Mueller.
Mueller is a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun in the inner main-belt at a distance of 1.7–2.1 AU once every 2 years and 8 months (983 days). Its orbit has an eccentricity of 0.10 and an inclination of 19° with respect to the ecliptic. The body was first identified as at Crimea–Nauchnij on 13 March 1969, yet the observation remained unused for the asteroid's observation arc.
Muellers spectral type is that of an E-type asteroid, typical for members of the Hungaria family. It has also been characterized as an X-type asteroid by PanSTARRS photometric survey.
Four rotational lightcurves for this asteroid were obtained from photometric observations made by American astronomer Brian Warner at his Palmer Divide Observatory between 2008 and 2016. They all gave a concurring, well-defined rotation period of 2.942 to 2.944 hours with a brightness variation between 0.14 and 0.19 magnitude .
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures 3.9 kilometers in diameter and its surface has a high albedo of 0.389, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 and calculates a diameter of 5.56 kilometers with an absolute magnitude of 13.2.
This minor planet was named after American astronomer Jean Mueller (b. 1950), discoverer of minor planets, comets and supernovae during the course of the Second Palomar Observatory Sky Survey (POSS II) using the Oschin Telescope at Palomar Observatory in the late 1980s and early 1990s. The official naming citation was published by the Minor Planet Center on 12 December 1989 .