243 Ida
The first asteroid found to have a moon of its own, spotted by Galileo in 1993.
Where it is right now
243 Ida is in Leo, 3.80 AU away, magnitude 15.5.
Computed for 2 August 2026, 17:00 UTC, and recomputed at least hourly. This page is cached, so treat the line above as accurate to the hour rather than to the second. The map shows the live position.
Position from a Kepler propagation of the published elements below, accurate to about an arcminute.
Facts
Every line carries the source it came from.
- Diameter
- 32 kmSource: NASA/JPL Small-Body Database
- Orbital period
- 4.8 yearsSource: NASA/JPL Small-Body Database
- Distance from the Sun
- 2.863 AU on averageSource: NASA/JPL Small-Body Database
- Orbit shape
- eccentricity 0.046, inclined 1.1 degrees to the eclipticSource: NASA/JPL Small-Body Database
- Class
- Main-belt asteroidSource: NASA/JPL Small-Body Database
- Discovered
- 1884-Sep-29 by Palisa, J.Source: NASA/JPL Small-Body Database
Physical size
- Mean radius
- 16.0 km
- Diameter
- 32 km across
- Absolute magnitude H
- 10.06
Orbit
Elements are heliocentric, referred to the J2000.0 ecliptic.
- Average distance from the Sun
- 2.863 AU (428.4 million km)
- Closest and furthest
- 2.731 AU (408.6 million km) to 2.995 AU (448.1 million km)
- Eccentricity
- 0.0461, almost circular
- Inclination to the ecliptic
- 1.13 degrees
- Orbital period
- 4.8 years (1,770 days)
- Longitude of ascending node
- 323.54 degrees
- Argument of periapsis
- 113.26 degrees
- Mean anomaly at J2000.0
- 245.53 degrees
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Catalog id ida. 3,172 objects on the map, of which 171 are hand-authored with sourced facts.