21389

21389 is a minor planet in the asteroid belt, located between the orbits of Mars and Jupiter. It was discovered on September 24, 1960, by the Indiana Asteroid Program at Goethe Link Observatory in Indiana, United States. The asteroid is named after the Indiana town of 21389, where the observatory is situated.

21389 has an estimated diameter of about 4 kilometers. Its orbit has a semi-major axis of approximately 2.7 astronomical units (AU), with an orbital period of about 4.4 Earth years. The asteroid's orbital eccentricity is 0.13, and its inclination to the ecliptic is around 10 degrees.

The spectral type of 21389 is S, indicating that it has a stony composition. This classification is based on its reflectance spectrum, which shows absorption bands typical of silicate minerals.

The asteroid's rotation period is approximately 5.6 hours. Its light curve, which shows variations in brightness as the asteroid rotates, has an amplitude of about 0.15 magnitudes, suggesting a relatively spherical shape.

21389 is not a potentially hazardous asteroid, as its orbit does not bring it close to Earth's orbit. However, its discovery and ongoing study contribute to our understanding of the asteroid belt and the formation of the solar system.