Key facts
- Category
- Asteroids
- Object class
- S-type main-belt asteroid
- Mass
- ~42 trillion metric tons
- Scale fact
- 59.8 kmmaximum extent
- Estimated age
- ~4.5 billion years
- Composition
- Silicate rock with metal
243 Ida
59.8 kmmaximum extent
Explore 243 Ida to scaleDetails
243 Ida is the elongated main-belt asteroid that NASA's Galileo spacecraft flew past in 1993, discovering that it has a tiny moon of its own – Dactyl. Ida became the first asteroid known to have a natural satellite, proving that even small bodies can hold companions.
Galileo photographed Ida during its 28 August 1993 flyby. Months later, researchers examining the images identified the 1.6-kilometer companion now called Dactyl—the first natural satellite discovered around an asteroid. The observation established that asteroids can be small multi-body systems, but the available images do not determine Dactyl's origin or a precise orbit.
Links
- Preset views
- Wikipedia
- 243 Ida on Wikipedia
Size neighbors
Objects near 243 Ida on the scale
On the logarithmic size axis, 243 Ida falls between Helene and 253 Mathilde. The band uses nearby S-type main-belt asteroid records.
Shared physical scale
45.7km
Sources
References for 243 Ida
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- 243 Ida — Wikipedia
- Visual reference: Wikimedia Commons (Galileo 1993 / NASA / JPL, Public domain)
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About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.