Key Facts

Overview

Egeria is a very large asteroid circling the sun between Mars and Jupiter, inside the main asteroid belt. NASA JPL does not treat Egeria as potentially hazardous, because its orbit never carries it near Earth.

One lap around the sun takes Egeria 1,510 days (4.13 years). Over that circuit it swings between 2.36 AU and 2.8 AU from the sun, travelling at an average of 18.56 km/s. At 202.6 kilometers across, Egeria is bigger than 99% of known asteroids — roughly the size of the U.S. state of Maryland.

Egeria has been watched long enough to time its spin: one full turn on its axis takes 7.05 hours.

Its spectral type — G on the Tholen scale, Ch on SMASSII — suggests Egeria holds water, iron, nickel, cobalt, nitrogen, and ammonia.

No Close Approaches

At their nearest, the orbits of Egeria and Earth stay 1.43 AU apart. That is a comfortable margin, and it holds at every point in the orbit.

Orbital simulations run by NASA JPL's CNEOS turn up no close approaches to Earth.

Images and Observations

The orbit of Egeria is pinned down by sightings going back to Nov. 21, 1850, the most recent officially logged on June 11, 2023. The IAU Minor Planet Center holds 3,311 observations behind that solution.

Accessibility and Exploration

The NHATS study does not rate Egeria as a realistic destination for a crewed mission.

Similar Objects

These objects follow orbits with much the same shape and tilt as Egeria:

References

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Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 2.576 AU
  • Eccentricity: 0.0856
  • Inclination: 16.54°
  • Longitude of Ascending Node: 43.21°
  • Argument of Periapsis: 79.83°
  • Mean Anomaly: 209.62°

Physical Characteristics

  • Diameter: 202.63600 km
  • Magnitude: 6.94
  • Albedo: 0.049
  • Spectral type (Tholen): G
  • Spectral type (SMASS): Ch

Derived Characteristics

  • Orbit Period: 1,510 days (4.13 years)
  • Avg. Orbit Speed: 18.56 km/s
  • Aphelion Distance: 2.8 AU
  • Perihelion Distance: 2.36 AU
  • Rotation Period: 7.05 hours
  • Approx. Composition: water, iron, nickel, cobalt, nitrogen, and ammonia

Map Comparison

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Orbit Simulation

Sky Map

A ◯ pink circle marks where Egeria sits. It may fall outside your current field of view — use the controls below to change the position, location and time.