| Minorplanet: | yes |
| Background: |
|
| 89 Julia | |
| Discovered: | 6 August 1866 |
| Mpc Name: | (89) Julia |
| Pronounced: | [1] |
| Adjective: | Julian |
| Epoch: | 31 July 2016 (JD 2457600.5) |
| Orbit Ref: |   |
| Semimajor: | 2.55016AU |
| Perihelion: | 2.08017AU |
| Aphelion: | 3.0202abbr=onNaNabbr=on |
| Eccentricity: | 0.18430 |
| Period: | 4.07 yr (1487.5 d) |
| Inclination: | 16.128° |
| Asc Node: | 311.563° |
| Arg Peri: | 45.461° |
| Dimensions: | c/a = (89±2)×(80±1)×(62±3) km |
| Mean Diameter: | [2] [3] |
| Mass: | |
| Density: | |
| Rotation: | (0.4745 day) |
| Magnitude: | 8.74 to 12.61 |
| Abs Magnitude: | 6.60 |
| Albedo: | 0.216 (calculated) 0.176 [4] |
| Angular Size: | 0.18" to 0.052" |
| Mean Motion: | / day |
| Observation Arc: | 149.68 yr (54672 d) |
| Uncertainty: | 0 |
89 Julia is a large main-belt asteroid that was discovered by French astronomer Édouard Stephan on 6 August 1866. This was first of his two asteroid discoveries; the other was 91 Aegina. 89 Julia is believed to be named after Saint Julia of Corsica. A stellar occultation by Julia was observed on 20 December 1985.
The spectrum of 89 Julia shows the signature of silicate rich minerals with possible indications of an abundant calcic clinopyroxene component. It is classified as an S-type asteroid. The asteroid has an estimated diameter of . Photometry from the Oakley Observatory during 2006 produced a lightcurve that indicated a sidereal rotation period of with an amplitude of in magnitude.
89 Julia is the parent body of the eponymous Julia family of asteroids. Observations of 89 Julia by the VLT's SPHERE instrument identified a 'highly probable' crater 70–80 km in diameter and deep in the southern hemisphere as the only visible possible source of the family.[5] The crater was named Nonza by the discoverers, referring to the commune on the island of Corsica where Saint Julia was born.[6] The excavated volume is on the order of 5,000 to . It is hypothesized an impact 30 to 120 million years ago by another body approximately 8 kilometers in diameter may have created the collisional family.