Somnium

Key Facts

• Categorized as a Main-belt Asteroid
• Comparable in size to the San Francisco Bay
• Not a Near Earth Object
• Not a Potentially Hazardous Object
• See orbit simulation

Overview

Somnium is a mid-sized asteroid orbiting between Mars and Jupiter in the main portion of the asteroid belt. NASA JPL has not classified Somnium as potentially hazardous because its orbit does not bring it close to Earth.

Somnium orbits the sun every 1,200 days (3.29 years), coming as close as 1.77 AU and reaching as far as 2.64 AU from the sun. Based on its brightness and the way it reflects light, Somnium is probably between 5.631 to 12.590 kilometers in diameter, making it larger than 99% of asteroids, very roughly comparable in size to the San Francisco Bay.

The rotation of Somnium has been observed. It completes a rotation on its axis every 5.34 hours.

Somnium's spectral type None (Tholen) / S (SMASSII) indicates that it is likely to contain and .

No Close Approaches

Somnium's orbit is 0.78 AU from Earth's orbit at its closest point. This means that there is a very 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

Somnium's orbit is determined by observations dating back to April 25, 1979. It was last officially observed on Dec. 24, 2022. The IAU Minor Planet Center records 3,096 observations used to determine its orbit.

Scientists have been able to determine this object's shape:

View asteroid Somnium in 3D.

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 Somnium:

• 8 Flora (A847 UA)
• 43 Ariadne (A857 GA)
• 228 Agathe (A882 QA)

References

• JPL Small Body Database
• Mission Design
• Sky Finder Chart

Orbit Simulation

Sky Map

The position of Somnium 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.