Key Facts

Overview

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

One lap around the sun takes Thetis 1,420 days (3.89 years). Over that circuit it swings between 2.14 AU and 2.8 AU from the sun, travelling at an average of 18.93 km/s. At 84.9 kilometers across, Thetis is bigger than 99% of known asteroids — roughly the size of the U.S. state of Delaware.

Thetis has been watched long enough to time its spin: one full turn on its axis takes 12.27 hours.

Thetis is classed as S on the Tholen scale, Sl on SMASSII.

No Close Approaches

At their nearest, the orbits of Thetis and Earth stay 1.13 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 Thetis is pinned down by sightings going back to April 17, 1852, the most recent officially logged on July 2, 2023. The IAU Minor Planet Center holds 10,707 observations behind that solution.

Accessibility and Exploration

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

Similar Objects

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

References

Search

   or view a random object

Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 2.471 AU
  • Eccentricity: 0.1325
  • Inclination: 5.59°
  • Longitude of Ascending Node: 125.53°
  • Argument of Periapsis: 135.72°
  • Mean Anomaly: 349.88°

Physical Characteristics

  • Diameter: 84.89900 km
  • Magnitude: 7.94
  • Albedo: 0.193
  • Spectral type (Tholen): S
  • Spectral type (SMASS): Sl

Derived Characteristics

  • Orbit Period: 1,420 days (3.89 years)
  • Avg. Orbit Speed: 18.93 km/s
  • Aphelion Distance: 2.8 AU
  • Perihelion Distance: 2.14 AU
  • Rotation Period: 12.27 hours

Map Comparison

Click to load map

Orbit Simulation

Sky Map

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