| Minorplanet: | yes |
| Background: |
|
| (148780) Altjira | |
| Discovered: | 20 October 2001 August 2006 (secondary) |
| Mpc Name: | (148780) Altjira |
| Adjective: | Altjirian |
| Mp Category: | Cubewano (DES)[1] |
| Orbit Ref: | [2] |
| Epoch: | 13 January 2016 (JD 2457400.5) |
| Semimajor: | 44.224AU |
| Perihelion: | 41.572AU |
| Aphelion: | 46.877abbr=onNaNabbr=on |
| Eccentricity: | 0.059979 |
| Period: | 294.10 yr (107421 d) |
| Inclination: | 5.2056° |
| Asc Node: | 2.0132° |
| Arg Peri: | 297.71° |
| Satellites: | 1 |
| Dimensions: | ≈128–200 (primary) and 100–180 km (secondary) |
| Mass: | 3.952×1018 kg |
| Density: | 0.5–2.0 g/cm3 |
| Abs Magnitude: | 5.7 5.6, 5.4, or 5.1 (primary) secondary's magnitude difference with primary's: 0.7 ± 0.2 |
| Albedo: | 0.06–0.14 |
| Observation Arc: | 2539 days (6.95 yr) |
| Uncertainty: | 3 |
| Mean Motion: | 0.0033513°/day |
148780 Altjira is a binary classical Kuiper belt object (cubewano).[3] The secondary, S/2007 (148780) 1, is large compared to the primary, 140km (90miles) vs. 160km (100miles). The Altjiran lightcurve is quite flat (Δmag<0.10), which is indicative of a "quasi-spherical body with a homogeneous surface".[4]
The satellite's orbit has the following parameters: semi-major-axis, ; period, ; eccentricity, ; and inclination, (retrograde). The total system mass is about 4 kg.[5]
It was named after the Arrernte creation deity, Altjira, who created the Earth during the Dreamtime and then retired to the sky.[2]
Altjira may be an unresolved hierarchical triple system.[6]