Eurybates
Key facts
- What it is
- Jupiter Trojan with a moon
- Size
- About 64 km across
- Discovered
- 1973
- Spacecraft
- Lucy fly-by planned for 2027
- Orbit group
- Jupiter Trojan
- Average distance from the Sun
- 5.22 au (about 780 million km)
- Time to go round the Sun
- 11.9 years
- Closest and farthest from the Sun
- 4.74 to 5.69 au
- Tilt of its orbit
- 8.1°
- Spins once every
- 8.7 hours
An au (astronomical unit) is Earth's average distance from the Sun, about 150 million km. Orbit figures are from open tracking data, figures last updated 1 Nov 2026.
Eurybates is a Trojan asteroid: one of a large population of bodies that share Jupiter's orbit around the Sun. The Trojans gather in two swarms, one about 60 degrees ahead of Jupiter and one about 60 degrees behind, at places where the pull of the Sun and of Jupiter balance in a way that keeps them stable for billions of years. Eurybates lies in the leading swarm.
The Trojans are among the most primitive objects in the Solar System. Many scientists think they formed further out, beyond the giant planets, and were captured into their present places when the giant planets shifted their orbits early in the Solar System's history. If so, they hold material from the outer Solar System in a place much easier to reach.
Eurybates is about 64 kilometres across and is the largest member of one of the few known families of collision fragments among the Trojans. In 2018 images from the Hubble Space Telescope revealed a tiny moon, only about a kilometre across, later named Queta.
NASA's Lucy spacecraft, launched in October 2021, is due to fly past Eurybates and Queta in August 2027, the first visit to any Trojan asteroid. It will go on to visit several more over the following years, finishing with the double Trojan Patroclus and Menoetius in 2033.
Like the other Trojans, Eurybates is named after a figure from the Trojan War. In the story, Eurybates was the herald of the Greek hero Odysseus.