Key Facts


Sirene is a mid-sized asteroid with an orbit that crosses the orbit of Mars. NASA JPL has not classified Sirene as potentially hazardous because its orbit does not bring it close to Earth.

Sirene orbits the sun every 1,560 days (4.27 years), coming as close as 1.44 AU and reaching as far as 3.82 AU from the sun. Based on its brightness and the way it reflects light, Sirene is probably between 4.411 to 9.864 kilometers in diameter, making it larger than 99% of asteroids, very roughly comparable in size to the San Francisco Bay.

No Close Approaches

Sirene's orbit is 0.45 AU from Earth's orbit at its closest point. This means that there is an wide berth between this asteroid and Earth at all times.

Orbital simulations conducted by NASA JPL's CNEOS do not show any close approaches to Earth.

Images and Observations

Sirene's orbit is determined by observations dating back to Oct. 31, 1923. It was last officially observed on June 16, 2020. The IAU Minor Planet Center records 919 observations used to determine its orbit.

Accessibility and Exploration

This asteroid is not considered a viable target for human exploration by the NHATS study.

Similar Objects

These objects have orbits that share similar characteristics to the orbit of Sirene:



   or view a random object

Orbital Elements

  • Epoch: 2459000.5 JD
  • Semi-major axis: 2.629 AU
  • Eccentricity: 0.4536
  • Inclination: 15.73°
  • Longitude of Ascending Node: 229.42°
  • Argument of Periapsis: 186.44°
  • Mean Anomaly: 243.22°

Physical Characteristics

  • Diameter: ~5.695 km
  • Magnitude: 13.9

Derived Characteristics

  • Orbit Period: 1,560 days (4.27 years)
  • Avg. Orbit Speed: 18.33 km/s
  • Aphelion Distance: 3.82 AU
  • Perihelion Distance: 1.44 AU

Map Comparison

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Orbit Simulation

Sky Map

The position of Sirene is indicated by a ◯ pink circle. Note that the object may not be in your current field of view. Use the controls below to adjust position, location, and time.