3 Juno
The third asteroid ever discovered, a large stony main-belt body — one of the historic first four minor planets.
Imagery
Juno orbit
Orbit of asteroid (3) Juno (blue, dashed line) compared to those of Earth, Mars and Jupiter (red, solid ellipses).
Omegaiota · Public domain
Orbit & physical parameters
Osculating orbit and physical parameters from the NASA JPL Small-Body Database · Main-belt Asteroid · epoch 2026-06-09 (JD 2461200.5 TDB) · Earth MOID 1.0383 au
| Semi-major axis | 2.67099 ± 1.4745e-9 au | NASA JPL · calculated |
| Eccentricity | 0.2557 ± 4.4009e-9 | NASA JPL · calculated |
| Perihelion distance | 1.988018 ± 1.2039e-8 au | NASA JPL · calculated |
| Aphelion distance | 3.353962 ± 1.8515e-9 au | NASA JPL · calculated |
| Inclination | 12.986592 ± 3.7253e-7 deg | NASA JPL · calculated |
| Longitude of ascending node | 169.811595 ± 2.1302e-6 deg | NASA JPL · calculated |
| Argument of perihelion | 247.895074 ± 2.2402e-6 deg | NASA JPL · calculated |
| Orbital period | 1,594 ± 1.3203e-6 d | NASA JPL · calculated |
| Diameter | 246.596 ± 10.594 km | NASA JPL · catalogued |
| Geometric albedo | 0.214 ± 0.026 | NASA JPL · estimated |
| Rotation period | 7.21 h | NASA JPL · catalogued |
| Absolute magnitude (H) | 5.19 mag | NASA JPL · catalogued |
Full field-level provenance
- Semi-major axis: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · a · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Eccentricity: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · e · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Perihelion distance: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · q · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Aphelion distance: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · ad · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Inclination: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · i · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Longitude of ascending node: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · om · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Argument of perihelion: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · w · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Orbital period: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · orbit.elements · per · JPL orbit determination (least-squares fit to the observation arc) · calculated · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Diameter: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · phys_par · phys.diameter · catalogued value · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Geometric albedo: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · phys_par · phys.albedo · Bayesian estimate · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Rotation period: Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · phys_par · phys.rot_per · catalogued value · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
- Absolute magnitude (H): Jet Propulsion Laboratory / Solar System Dynamics · JPL SBDB · phys_par · phys.H · catalogued value · JPL solution by Otto Matic, 8343 obs · retrieved 2026-07-11
Orbital elements are a calculated JPL orbit-determination fit, all referred to the single osculating epoch above (solution by Otto Matic); each carries its own uncertainty. Fields the database did not provide are omitted, never invented.
Populations
Knowledge connections
- Member of groupMain Asteroid Belt
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
- NASA JPLJet Propulsion Laboratory / Solar System Dynamics
Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.