| Minorplanet: | yes |
| 228 Agathe | |
| Background: |
|
| Discovery Ref: |   |
| Discovered: | 19 August 1882 |
| Mpc Name: | (228) Agathe |
| Alt Names: | A882 QA |
| Named After: | Theodor v. Oppolzer  |
| Orbit Ref: |   |
| Epoch: | 13 September 2023 (JD 2453300.5) |
| Uncertainty: | 0 |
| Observation Arc: | 130.80 yr |
| Aphelion: | 2.73abbr=unitNaNabbr=unit |
| Perihelion: | 1.67AU |
| Semimajor: | 2.2AU |
| Eccentricity: | 0.24227 |
| Period: | 3.27 yr (1193.1 d) |
| Inclination: | 2.5359° |
| Asc Node: | 313.25° |
| Arg Peri: | 19.177° |
| Moid: | 0.657AU |
| Mars Moid: | 0.29AU |
| Rotation: | 6.484abbr=onNaNabbr=on |
| Abs Magnitude: | 12.32 |
| Mean Motion: | / day |
| Jupiter Moid: | 2.63AU |
| Tisserand: | 3.624 |
228 Agathe is a stony main belt asteroid, about 9 kilometers in diameter. It was discovered by Johann Palisa on 19 August 1882 at Vienna Observatory, Austria. Photometric observations during 2003 showed a rotation period of 6.48 ± 0.01 hours with a brightness variation of 0.27 ± 0.03 in magnitude. An earlier study yielded results that are consistent with these estimates. Agathe is the lowest numbered asteroid to have an Earth-MOID as low as 0.657abbr=unitNaNabbr=unit. On 23 August 2029 the asteroid will be 0.659abbr=unitNaNabbr=unit from Earth.
| 23 August 2029 ≈07:22 | 0.6597abbr=unitNaNabbr=unit | 1.67AU | 3.9 | 25.7 | ± 1.4 km | 177.9° |
Agathe was named after the youngest daughter of Austrian astronomer Theodor von Oppolzer (1841–1886), professor of astronomy in Vienna.